View Full Version : What's the consensus on carbon fiber barrels?
I'm having a hard time understanding how it could improve anything but trying to keep an open mind.
A buddy just got one for his LMT MWS. I guess weight savings is a positive.
bamashooter
12-12-22, 08:48
Simple stuff but, costly. Lighter, stronger, cooler. Any improved accuracy remains with the shooter.
Simple stuff but, costly. Lighter, stronger, cooler. Any improved accuracy remains with the shooter.
When people say "cooler" I can only imagine they're talking about the carbon fiber insulating the barrel, but that has to be the most counterproductive thing you could do for accuracy. It sounds like they're literally wrapping the barrels in a highly insulative material thereby preventing the barrel from dissipating heat. I see how that would stiffen the barrel which could be good for very low volume (like a hunting rifle where you only take one shot), but how it could be productive for an AR barrel I just don't understand.
When people say "cooler" I can only imagine they're talking about the carbon fiber insulating the barrel, but that has to be the most counterproductive thing you could do for accuracy. It sounds like they're literally wrapping the barrels in a highly insulative material thereby preventing the barrel from dissipating heat. I see how that would stiffen the barrel which could be good for very low volume (like a hunting rifle where you only take one shot), but how it could be productive for an AR barrel I just don't understand.
Carbon fiber by itself is a conductive material, but not nearly as efficient as metal so there’s a misconception that it’s an insulator. That being said I completely torched a proof research barrel on my AR a couple of years ago during a competition season, and I absolutely agree it should be limited to low volume of fire situations.
Carbon fiber by itself is a conductive material, but not nearly as efficient as metal so there’s a misconception that it’s an insulator. That being said I absolutely torched a proof research barrel on my AR a couple of years ago during a competition season, and I absolutely agree it should be limited to low volume of fire situations.
I'm mostly just not understanding how the carbon fiber is helping anything on any barrel meant to fire more than one shot consecutively (i.e. anything but a hunting rifle). Seems like it would do nothing but make the bore get hotter faster and make it dissipate that heat slower. I can't think of any reason that it's functionally any different from taking a pencil barrel and wrapping it in insulation.
I'm mostly just not understanding how the carbon fiber is helping anything on any barrel meant to fire more than one shot consecutively (i.e. anything but a hunting rifle). Seems like it would do nothing but make the bore get hotter faster and make it dissipate that heat slower. I can't think of any reason that it's functionally any different from taking a pencil barrel and wrapping it in insulation.
Very, very stiff insulation.
Very, very stiff insulation.
I get it's stiff, but stiffness isn't the limiting factor with ARs, or even most bolt actions, especially if they're floated. The main reason for a bull barrel isn't stiffness or harmonics or whatever but just to keep the bore cooler. I mean anyone who's shot a pencil barrel and a bull barrel can attest to how cool the bull barrel stays. And I get that the carbon wrapped barrel will be cool to the touch, but that doesn't mean that the metal under it is.
The proof carbon barrels are great on long range hunting guns, where you want the accuracy of a precision barrel, but much lighter than a PRS type setup. I think that's where they excel.
I don't personally think they have much place on a gas gun, but i've also only shot one on a semi-auto .22, so maybe i'm missing something. In the long range PRS competition world, it seems things are going towards "the heavier is better" model, with more heavy straight tapered steel barrels for reduced recoil etc.
The main reason for a bull barrel isn't stiffness or harmonics or whatever but just to keep the bore cooler.
This is news to me, and probably everyone else reading this read.
This is news to me, and probably everyone else reading this read.
I thought that initially, but I think both are considerations that some people might weight differently. If I’m using a heavy profile barrel, its for precision reasons; if I’m using a medium profile barrel, its partly for heat, and partly for performance. If I’m using a pencil, its because I’m lazy. I’ve been curious about carbon wrap barrels for some time, and I might try one on a bolt one day.
Do carbon wrapped AR barrels tension/pull traction on the underlying steel?
This is news to me, and probably everyone else reading this read.
I'm not saying it doesn't matter, I'm just saying that a pencil barrel can shoot sub MOA with a cold bore. It's heat expansion from volume that kills AR accuracy, not lack of stiffness or any such thing.
I'm not saying it doesn't matter, I'm just saying that a pencil barrel can shoot sub MOA with a cold bore. It's heat expansion from volume that kills AR accuracy, not lack of stiffness or any such thing.
I’ve been trending toward the idea that they aren’t optimal for repeatable precision and accuracy. It seems a little easier to work up a decent load or grab whatever’s on the shelf, and reach your accuracy goals, repeatably. A 3-shot group with 69gr FGMM, sure. Most any barrel can shoot that acceptably. But I’ve got an older Noveske stainless thats thicc and shoots anything pretty well.
My sample size has limits, and I don’t PRS or Benchrest, so I have to defer to the experts. But in my sampling, its been easier to get excellent results with a chubby barrel than a skinny one, at their extremes.
I get it's stiff, but stiffness isn't the limiting factor with ARs, or even most bolt actions, especially if they're floated. The main reason for a bull barrel isn't stiffness or harmonics or whatever but just to keep the bore cooler. I mean anyone who's shot a pencil barrel and a bull barrel can attest to how cool the bull barrel stays. And I get that the carbon wrapped barrel will be cool to the touch, but that doesn't mean that the metal under it is.
Not sure where you heard that crap but yes it IS for rigidity. The taking longer to heat up thing is an added bonus.
You can easily get a bull barrel just as hot as a skinny barrel - It just takes a little longer (and then a little longer to cool back down)
Why does the heavy barrel STILL not 'string' for squat once it is so hot you can cook bacon on it as compared to what a pencil barrel would do if heated up the same way???
I’ve been trending toward the idea that they aren’t optimal for repeatable precision and accuracy. It seems a little easier to work up a decent load or grab whatever’s on the shelf, and reach your accuracy goals, repeatably. A 3-shot group with 69gr FGMM, sure. Most any barrel can shoot that acceptably. But I’ve got an older Noveske stainless thats thicc and shoots anything pretty well.
My sample size has limits, and I don’t PRS or Benchrest, so I have to defer to the experts. But in my sampling, its been easier to get excellent results with a chubby barrel than a skinny one, at their extremes.
Stick with what you you know here brother because you would be correct...
I would like to see a comparison between carbon fiber barrels, and highly fluted barrels such as on the earliest AR10 rifles. The first several US made AR10s had highly fluted aluminum barrels with steel liners. One sploded during a full auto torture test. Only maybe one or two of the earliest guns still wears aluminum, the rest being retrofitted to all steel The Dutch made very 100% nice steel barrels for their AR10s that are crazy fluted. see pic. Resulted in the rifle weighing less that 7 lbs.
https://i.ibb.co/QKbCsKF/11t4f87.jpg
I would like to see a comparison between carbon fiber barrels, and highly fluted barrels such as on the earliest AR10 rifles. The first several US made AR10s had highly fluted aluminum barrels with steel liners. One sploded during a full auto torture test. Only maybe one or two of the earliest guns still wears aluminum, the rest being retrofitted to all steel The Dutch made very 100% nice steel barrels for their AR10s that are crazy fluted. see pic. Resulted in the rifle weighing less that 7 lbs.
1) It wasn't a full auto torture test, just the standard 6,000 round endurance test, and s/n 1002 let go at round number 5,564. S/n 1004 was being tested in other areas, and had fewer rounds through it.
2) Both test guns (s/n 1002 and 1004) had all steel barrels fitted before test resumed. But there were a lot of other, bigger, problems encountered, the gas tubes warped, the gas tube connections broke off, they fouled badly, to the point of ceasing to function after 500 rounds, the extractors broke, and they had a bad tendency to shoot holes in their own flash suppressor.
3) The AR-10 only weighed less than 7 pounds in the advertising, the lightest version was the aluminum barrel version that weighed 7.35 lbs when tested, empty, no magazine or sling. By 1960, it had gained a little weight and test weights were 8.80 lbs.
...3) The AR-10 only weighed less than 7 pounds in the advertising, the lightest version was the aluminum barrel version that weighed 7.35 lbs when tested, empty, no magazine or sling. By 1960, it had gained a little weight and test weights were 8.80 lbs.
The earliest Dutch AR10 variant (Cuban) weighed less than 7 lbs empty and had an all-steel barrel. See press release below. I have verified this weight personally. The Cuban AR10 had the crazy fluted barrel (pic above), no bayonet lug, and a lighter bolt carrier. The later AR10 variants added weight and durability. The Portuguese variant, for example, had a much heavy barrel (un-fluted).
https://i.ibb.co/mN6rrGF/Cuban-Lemnitzer.jpg
Not sure where you heard that crap but yes it IS for rigidity. The taking longer to heat up thing is an added bonus.
You can easily get a bull barrel just as hot as a skinny barrel - It just takes a little longer (and then a little longer to cool back down)
Why does the heavy barrel STILL not 'string' for squat once it is so hot you can cook bacon on it as compared to what a pencil barrel would do if heated up the same way???
Any barrel will string when it gets hot enough to expand. As I said several times, thicker barrels take a lot longer to heat up, and they dissipate heat faster into the air due to having more surface area. A bull barrel has roughly twice the surface area as a pencil and roughly three times the mass.
From a cold bore, any profiles turned from the same blanks firing the same ammunition will shoot just about the same, but a lighter profile will start to wander within about five shots, whereas a thicker profile might take 20 shots before it gets hot enough to start expanding. The difference between a heavy and light profile AR barrel isn't really relevant to the platform or the way its used, from a rigidity perspective. The whole platform has all kinds of other issues. It's not a precision rifle. You have a barrel slopped into an aluminum receiver and a bolt that doesn't stay square to the chamber when the cartridge is pressurized. Worrying about rigidity in an AR barrel at the expense of thermal mass and heat dissipation is like worrying about the effect of aerodynamics on the acceleration of a minivan.
worrying about the effect of aerodynamics on the acceleration of a minivan. This is GOOD!
But if your minivan has AWD, decent aerodynamics, and a good engine, it can still get moving faster than an average sedan.
Just saying. I like our Sienna.
From a cold bore, any profiles turned from the same blanks firing the same ammunition will shoot just about the same, but a lighter profile will start to wander within about five shots, whereas a thicker profile might take 20 shots before it gets hot enough to start expanding. The difference between a heavy and light profile AR barrel isn't really relevant to the platform or the way its used, from a rigidity perspective. The whole platform has all kinds of other issues. It's not a precision rifle.
Will bet that you do not own and have never owned an AR15 with a bull barrel. Not even one... :)
https://i.imgur.com/Mj2WCvE.jpg
20 rounds my ass. :)
You have a barrel slopped into an aluminum receiver and a bolt that doesn't stay square to the chamber when the cartridge is pressurized.
The bolt is not held square to the chamber? FALSE
The locking faces of the lugs on the extension, and the front face are held square to the threads.
The bore of the barrel is held square to the thread buttress.
So, when the barrel extension is threaded on to the barrel the locking faces of the lugs are square the bore and chamber axis.
The rear faces of the bolt's locking lugs are held square to the breech face.
The breech face is perpendicular to the chamber and bore to within 0.0005".
Also, the upper is square enough to the barrel, per print, and the carrier has enough clearance, to keep allow the bolt to go square to the barrel without interference from the upper.
Worrying about rigidity in an AR barrel at the expense of thermal mass and heat dissipation is like worrying about the effect of aerodynamics on the acceleration of a minivan.
So, explain fluted barrels, that have been used from the very beginnings of the AR-10/AR-15? If it were only about soaking up heat in a massive body, flutes would be pointless.
Or, the USMC specifically requesting the M16A2 have the "HBAR" barrel, due to its better rigidity.
titsonritz
12-14-22, 14:29
Any barrel will string when it gets hot enough to expand. As I said several times, thicker barrels take a lot longer to heat up, and they dissipate heat faster into the air due to having more surface area. A bull barrel has roughly twice the surface area as a pencil and roughly three times the mass.
From a cold bore, any profiles turned from the same blanks firing the same ammunition will shoot just about the same, but a lighter profile will start to wander within about five shots, whereas a thicker profile might take 20 shots before it gets hot enough to start expanding. The difference between a heavy and light profile AR barrel isn't really relevant to the platform or the way its used, from a rigidity perspective. The whole platform has all kinds of other issues. It's not a precision rifle. You have a barrel slopped into an aluminum receiver and a bolt that doesn't stay square to the chamber when the cartridge is pressurized. Worrying about rigidity in an AR barrel at the expense of thermal mass and heat dissipation is like worrying about the effect of aerodynamics on the acceleration of a minivan.
So which is the very bestest for innagrass shooting?
An AR can absolutely be a precision rifle. Do you read Molon’s posts?
So which is the very bestest for innagrass shooting?
The one with iron sights.
titsonritz
12-14-22, 17:14
The one with iron sights.
Oh man, you got me. :jester:
The bolt is not held square to the chamber? FALSE
The locking faces of the lugs on the extension, and the front face are held square to the threads.
The bore of the barrel is held square to the thread buttress.
So, when the barrel extension is threaded on to the barrel the locking faces of the lugs are square the bore and chamber axis.
The rear faces of the bolt's locking lugs are held square to the breech face.
The breech face is perpendicular to the chamber and bore to within 0.0005".
Also, the upper is square enough to the barrel, per print, and the carrier has enough clearance, to keep allow the bolt to go square to the barrel without interference from the upper.
So, explain fluted barrels, that have been used from the very beginnings of the AR-10/AR-15? If it were only about soaking up heat in a massive body, flutes would be pointless.
Or, the USMC specifically requesting the M16A2 have the "HBAR" barrel, due to its better rigidity.
Flutes theoretically increase surface area and dissipate heat faster. The AR's bolt tilts slightly when under pressure. The military says and does stupid stuff all the time. They also thought the M16A1's barrels were bending so...
But we're getting way off track here. What I want to know specifically is if there's some magic in the carbon composites used with barrels that enables them to conduct heat, or if it's as I suspect and they're just insulating the barrel and making the whole situation worse.
Does carbon fiber wrap resist bending caused by heat better than barrel steel? If so, is it a lighter method of keeping the barrel straight?
...So, explain fluted barrels, that have been used from the very beginnings of the AR-10/AR-15? If it were only about soaking up heat in a massive body, flutes would be pointless....
Reed Knight (KAC) told me that the deep AR10 flutes added rigidity as well as surface area. This is not intuitive (to me). Added rigidity as compared to what?
Reed Knight (KAC) told me that the deep AR10 flutes added rigidity as well as surface area. This is not intuitive (to me). Added rigidity as compared to what?
A barrel of the same weight.
Not a barrel of the same profile.
pointblank4445
12-15-22, 17:10
Given that Proof was supposed to have the key to unlocking the problems with CF, I'll use them
Had a Proof in an SPR...super accurate from a given position. If you went from prone/bipod to say a tripod, you could see a group walk 9+ MOA (over 4x more than we can make other barrels walk in similar situations) by changes in position/external pressures
I also noted that there were some respected industry trainer types that were very vocal about their hot new Proof barrels for their training guns. Knowing how my experience had been, I waited for feedback that never came. They very quietly removed their CF barrels some time later and never spoke of them. Very curious...
Last but not least hearing it from guys shooting 3-gun competition with Proof CF barrels talk about the cons compared to their stainless Proof barrels and how none would willingly opt for them in personal guns.
I absolutely would do a CF barrel again...
...but it would be a Bartlein, and it damn sure would NOT be in a semi-auto either.
Does carbon fiber wrap resist bending caused by heat better than barrel steel? If so, is it a lighter method of keeping the barrel straight?
Steel's modulus to my knowledge is essentially unchanged until you start getting into meltdown territory. I don't have numbers off the top of my head, but for a normal firing schedule I'm very confident in assuming that the barrel's rigidity won't be appreciably affected. What causes stringing as a barrel heats up isn't loss of rigidity but the diameter of the bore increasing as the steel expands. Steel expands about half to one percent per 100 degree increase in temperature, so a steaming hot barrel would probably have increased in diameter about 3-5%. Which doesn't sound like much, but even a 1% increase in bore diameter is relatively meaningful.
Think about it this way. If you've ever had a part with an interference fit that you can't quite get to go, you can heat up the female part with a heat gun and generally about 300 degrees will take you from an interference fit to slip fit and make it easy to assemble. Like if you've ever had a keyway that just refuses to come out no matter how much you persuade it, then you hit it with a little heat and it just pops right out.
Reed Knight (KAC) told me that the deep AR10 flutes added rigidity as well as surface area. This is not intuitive (to me). Added rigidity as compared to what?
As counterintuitive as it sounds, strategically removing material does increase rigidity by redirecting force vectors.
A barrel of the same weight.
Not a barrel of the same profile.
A barrel can be made more rigid without changing the profile by simply fluting it.
A barrel can be made more rigid without changing the profile by simply fluting it.
Geometrically illogical.
Steel's modulus to my knowledge is essentially unchanged until you start getting into meltdown territory. I don't have numbers off the top of my head, but for a normal firing schedule I'm very confident in assuming that the barrel's rigidity won't be appreciably affected. What causes stringing as a barrel heats up isn't loss of rigidity but the diameter of the bore increasing as the steel expands. Steel expands about half to one percent per 100 degree increase in temperature, so a steaming hot barrel would probably have increased in diameter about 3-5%. Which doesn't sound like much, but even a 1% increase in bore diameter is relatively meaningful.
Think about it this way. If you've ever had a part with an interference fit that you can't quite get to go, you can heat up the female part with a heat gun and generally about 300 degrees will take you from an interference fit to slip fit and make it easy to assemble. Like if you've ever had a keyway that just refuses to come out no matter how much you persuade it, then you hit it with a little heat and it just pops right out.
This is new to me, seems obvious when pointed out. Thank You
I like light rifles and have read into Pencil barrel info.
The bending issue was explained by residual stress in the steel expressing itself as heated.
Faxon says they "normalize" their barrels and this results in latent stress being minimized.
Please comment on that as a possible cause of "heat bending".
gunnerblue
12-16-22, 15:01
Given that Proof was supposed to have the key to unlocking the problems with CF, I'll use them
Had a Proof in an SPR...super accurate from a given position. If you went from prone/bipod to say a tripod, you could see a group walk 9+ MOA (over 4x more than we can make other barrels walk in similar situations) by changes in position/external pressures
I also noted that there were some respected industry trainer types that were very vocal about their hot new Proof barrels for their training guns. Knowing how my experience had been, I waited for feedback that never came. They very quietly removed their CF barrels some time later and never spoke of them. Very curious...
Last but not least hearing it from guys shooting 3-gun competition with Proof CF barrels talk about the cons compared to their stainless Proof barrels and how none would willingly opt for them in personal guns.
I absolutely would do a CF barrel again...
...but it would be a Bartlein, and it damn sure would NOT be in a semi-auto either.
Given that my Proof-barreled hunting rifles (bolts) heat up to the touch noticeably after only a few shots, I'd be interested to know how much heat is still in the steel barrel itself and not being conducted through the wrap. At any rate, I went with CF for weight savings and sustainable long range accuracy and in that application I don't think they can be beat.
This is new to me, seems obvious when pointed out. Thank You
I like light rifles and have read into Pencil barrel info.
The bending issue was explained by residual stress in the steel expressing itself as heated.
Faxon says they "normalize" their barrels and this results in latent stress being minimized.
Please comment on that as a possible cause of "heat bending".
I've never heard the term heat bending before, but I think what they're talking about is dipping the barrel in liquid nitrogen to normalize it. It's very common if not universal in barrel manufacturing.
Given that my Proof-barreled hunting rifles (bolts) heat up to the touch noticeably after only a few shots, I'd be interested to know how much heat is still in the steel barrel itself and not being conducted through the wrap. At any rate, I went with CF for weight savings and sustainable long range accuracy and in that application I don't think they can be beat.
I agree 100% that carbon wrapped barrels make perfect sense for hunting rifles, at least in theory. What I'm questioning specifically is dudes putting them on their recce style ARs and thinking that's somehow improving their situation.
Geometrically illogical.
How so???
A barrel can be made more rigid without changing the profile by simply fluting it.
Nope. You take away mass and that barrel becomes less rigid.
How so???
Lets do a thought experiment. Take a .750” diameter barrel. Cut 6 deep longitudinal flutes in it. The high spots total to 50% of the circumference and are of the original diameter. By your logic, it retains its original stiffness, because it retains a certain amount of metal at the original circumference, right? Ok, lets add the original metal back…is it now twice the strength it was before fluting? What if we go the other way…hog out the flutes so the cross section is like, I dunno .500”, with 6 razor thin fins out to .750”…. Still just as strong as the original? Cut the flutes deeper…down to .25”, paper thin around the bore. Should be nice and light, and just as stiff as the original straight profile .750”, right? Nah. You could put some gloves on and bend that in half.
Nope. You take away mass and that barrel becomes less rigid.
Maybe in practice, but in theory I'm sure a good enough engineer could find a way to actually increase rigidity by removing material. I don't know exactly what it would look like, or if the result would be in any way practical, but I'm sure it's possible, if that were the only goal. I've seen all kinds of wild fluting patterns so maybe it's already been done, idk. The guy mentioned worked for knights and they do that ball mill fluting so maybe, idk that's way above my pay grade. I could definitely see though how that might alleviate the localized strain where it's trying to compress in the direction of the deflection.
Just in principle though it's not a big secret that in certain situations removing material can be helpful. A simple fillet would be the classic example how actually removing material can increase both rigidity and strength.
Lets do a thought experiment. Take a .750” diameter barrel. Cut 6 deep longitudinal flutes in it. The high spots total to 50% of the circumference and are of the original diameter. By your logic, it retains its original stiffness, because it retains a certain amount of metal at the original circumference, right? Ok, lets add the original metal back…is it now twice the strength it was before fluting? What if we go the other way…hog out the flutes so the cross section is like, I dunno .500”, with 6 razor thin fins out to .750”…. Still just as strong as the original? Cut the flutes deeper…down to .25”, paper thin around the bore. Should be nice and light, and just as stiff as the original straight profile .750”, right? Nah. You could put some gloves on and bend that in half.
You're going to have an area of localized strain in the middle of the barrel. On one side a very small area is taking most of the compression, and opposite that another small area that's taking most of the elongation. If you can find a strategy to remove material and distribute those areas of highly localized strain throughout the barrel then yes you could probably increase strength and rigidity. Again, I don't know what that would look like, or if straight flutes accomplish that goal. I could see how they might though. Obviously the shape and size of the flutes is something that you can't just guess at. Again, above my pay grade.
I agree 100% that carbon wrapped barrels make perfect sense for hunting rifles, at least in theory. What I'm questioning specifically is dudes putting them on their recce style ARs and thinking that's somehow improving their situation.
I can envision a properly organized AR build based on a carbon wrapped Bbl. A hunting or "walk about" rig where in a perfect world you have a low volume of fire - couple rounds now and then to verify sights / put meat in the larder. If your world suddenly became "less perfect" you still have a tool that could send some rounds down range in short order.
Probably not a build I would pursue, and to your point I don't see it significantly improving anyone's situation - but maybe a viable option ? Guess it would be like most tools - best results come from an understanding of what it is and what it is not.
Maybe in practice, but in theory I'm sure a good enough engineer could find a way to actually increase rigidity by removing material. I don't know exactly what it would look like, or if the result would be in any way practical, but I'm sure it's possible, if that were the only goal. I've seen all kinds of wild fluting patterns so maybe it's already been done, idk. The guy mentioned worked for knights and they do that ball mill fluting so maybe, idk that's way above my pay grade. I could definitely see though how that might alleviate the localized strain where it's trying to compress in the direction of the deflection.
Just in principle though it's not a big secret that in certain situations removing material can be helpful. A simple fillet would be the classic example how actually removing material can increase both rigidity and strength.
Sorry, no.
Removal of material will always reduce stiffness.
Removal of material will always reduce weight.
Removal of material may result in less static droop, but that is not the same as stiffness.
Sorry, no.
Removal of material will always reduce stiffness.
Removal of material will always reduce weight.
Removal of material may result in less static droop, but that is not the same as stiffness.
That is just thoroughly false. There are lots of situations where removing material can increase rigidity and or strength by distributing localized strain, reducing vibration, lowering inertia, etc. I'm not in a position to say if traditional flutes do any of that to a barrel or not, but if the aforementioned engineer at Knight's really said that then he's probably right because it is hypothetically possible.
One example I can think of would be tapering a bull barrel. By tapering the barrel it has less mass at the end and that will reduce the stress applied during barrel whip without compromising stiffness. That material at the end of the barrel is essentially doing nothing, as all the strain is isolated more towards the middle. The reason they leave that material on a bull barrel is to resist thermal expansion at the crown.
Where’s my popcorn?[emoji897][emoji897]
That is just thoroughly false. There are lots of situations where removing material can increase rigidity and or strength by distributing localized strain, reducing vibration, lowering inertia, etc. I'm not in a position to say if traditional flutes do any of that to a barrel or not, but if the aforementioned engineer at Knight's really said that then he's probably right because it is hypothetically possible.
One example I can think of would be tapering a bull barrel. By tapering the barrel it has less mass at the end and that will reduce the stress applied during barrel whip without compromising stiffness. That material at the end of the barrel is essentially doing nothing, as all the strain is isolated more towards the middle. The reason they leave that material on a bull barrel is to resist thermal expansion at the crown.Okie, would you care to give us a brief CV so we can take you a bit more seriously, please? You make general statements about, "lots of situations," but I think we'd like some enumeration of just a couple of those "situations."
Examples using math would be the most convincing. Thank you.
That is just thoroughly false. There are lots of situations where removing material can increase rigidity and or strength by distributing localized strain, reducing vibration, lowering inertia, etc. I'm not in a position to say if traditional flutes do any of that to a barrel or not, but if the aforementioned engineer at Knight's really said that then he's probably right because it is hypothetically possible.
One example I can think of would be tapering a bull barrel. By tapering the barrel it has less mass at the end and that will reduce the stress applied during barrel whip without compromising stiffness. That material at the end of the barrel is essentially doing nothing, as all the strain is isolated more towards the middle. The reason they leave that material on a bull barrel is to resist thermal expansion at the crown.
You fail mechanics of materials.
Stiffness is normally denoted as k
k = 3EI/L^3
with:
E = modulus of elasticity
L = length
I = second area moment of the cross-section
So, let us look at two barrels, the one a straight one inch in diameter, and the other tapered, starting at one inch and tapering to 0.500 inch at the muzzle. Both are the same caliber, overall length and made from the same material, so L and E will be the same, so the only thing than changes the stiffness is I
I for a round cross section with a round hole in its center (a thick walled tube) is:
(π/4) x [(R2^4) - (R1^4)]
with:
R1 = inside diameter (bore which is constant)
R2 = outside diameter
Since R2 on the straight sided barrel in constant, and R2 on the tapered barrel starts at 1 but decreases to 0.50. Therefore, I for the tapered barrel will always be less than I for the straight barrel, as will the stiffness.
You fail mechanics of materials.
Stiffness is normally denoted as k
k = 3EI/L^3
with:
E = modulus of elasticity
L = length
I = second area moment of the cross-section
So, let us look at two barrels, the one a straight one inch in diameter, and the other tapered, starting at one inch and tapering to 0.500 inch at the muzzle. Both are the same caliber, overall length and made from the same material, so L and E will be the same, so the only thing than changes the stiffness is I
I for a round cross section with a round hole in its center (a thick walled tube) is:
(π/4) x [(R2^4) - (R1^4)]
with:
R1 = inside diameter (bore which is constant)
R2 = outside diameter
Since R2 on the straight sided barrel in constant, and R2 on the tapered barrel starts at 1 but decreases to 0.50. Therefore, I for the tapered barrel will always be less than I for the straight barrel, as will the stiffness.
But reducing stiffness in that area in this case is irrelevant. It might be relevant with a big heavy silencer or perhaps a bipod located at the very end of the barrel like on some MGs, but as far as a bare muzzle is concerned reducing the stiffness at the end of the barrel isn't going to result in greater deflection at the muzzle. And with the reduced inertia it should result in less, at least theoretically. Point is, a barrel with a slight taper isn't going to whip more, and might even whip measurably less.
But reducing stiffness in that area in this case is irrelevant. It might be relevant with a big heavy silencer or perhaps a bipod located at the very end of the barrel like on some MGs, but as far as a bare muzzle is concerned reducing the stiffness at the end of the barrel isn't going to result in greater deflection at the muzzle. And with the reduced inertia it should result in less, at least theoretically. Point is, a barrel with a slight taper isn't going to whip more, and might even whip measurably less.
Read the room.
I've never heard the term heat bending before, but I think what they're talking about is dipping the barrel in liquid nitrogen to normalize it. It's very common if not universal in barrel manufacturing.
Normalizing is heat treatment where the steel is completely recrystalized and slowly brought down in temp to remove any stresses. It results in a full-soft temper.
I think you are referring to cryogenic treatments, which Im unfamiliar with.
But reducing stiffness in that area in this case is irrelevant. It might be relevant with a big heavy silencer or perhaps a bipod located at the very end of the barrel like on some MGs, but as far as a bare muzzle is concerned reducing the stiffness at the end of the barrel isn't going to result in greater deflection at the muzzle. And with the reduced inertia it should result in less, at least theoretically. Point is, a barrel with a slight taper isn't going to whip more, and might even whip measurably less.
First off, you said it was false that removing material always reduces stiffness. I showed that stiffness will always be reduced when material is removed, because the 2nd moment of cross section area is the moment of the area, and with a tube, if the area is smaller, the stiffness will be smaller.
The only way to increase stiffness of a tube is to increase the cross section area.
And, all of the barrel moves when it whips, so more overall stiffness is always better, even if only by a teeny, tiny amount.
First off, you said it was false that removing material always reduces stiffness. I showed that stiffness will always be reduced when material is removed, because the 2nd moment of cross section area is the moment of the area, and with a tube, if the area is smaller, the stiffness will be smaller.
The only way to increase stiffness of a tube is to increase the cross section area.
And, all of the barrel moves when it whips, so more overall stiffness is always better, even if only by a teeny, tiny amount.
The strain is concentrated at or near the chamber, can we agree on that? I get that the stiffness is reduced at the point where the material is removed, but the strain is far, far less at the muzzle, and the deleted material will reduce strain at the base where it's most concentrated. Same reason a flag pole is tapered.
Therefore, the tapered barrel will not deflect more than a non tapered one. Not due to barrel whip, or even due to loading in the case of a non free floated barrel. Reducing stiffness at an area where there's less strain does not reduce the overall stiffness of the barrel with regard to how it's stressed. In other words, it effectively increases the stiffness of the barrel.
And yes I get that that's not the definition of stiffness but that's what people mean when they talk about the stiffness or rigidity of a barrel, which you obviously know good and well and are just here to harass me but whatever. Apparently I'm the resident whipping boy now so have at it.
Normalizing is heat treatment where the steel is completely recrystalized and slowly brought down in temp to remove any stresses. It results in a full-soft temper.
I think you are referring to cryogenic treatments, which Im unfamiliar with.
Yes sir you're right that's what I meant but I couldn't remember what it was called.
The strain is concentrated at or near the chamber, can we agree on that? I get that the stiffness is reduced at the point where the material is removed, but the strain is far, far less at the muzzle, and the deleted material will reduce strain at the base where it's most concentrated. Same reason a flag pole is tapered.
Therefore, the tapered barrel will not deflect more than a non tapered one. Not due to barrel whip, or even due to loading in the case of a non free floated barrel. Reducing stiffness at an area where there's less strain does not reduce the overall stiffness of the barrel with regard to how it's stressed. In other words, it effectively increases the stiffness of the barrel.
And yes I get that that's not the definition of stiffness but that's what people mean when they talk about the stiffness or rigidity of a barrel, which you obviously know good and well and are just here to harass me but whatever. Apparently I'm the resident whipping boy now so have at it.
First "strain" is directly proportional to the amount of deformation experienced by an object under loading. Therefore, it is not concentrated at or near the chamber, but where the barrel sees the highest bending, say in between nodes?
So, you might want to rethink that last statement.
Short argument, people have been making bull barrels for low rate fire accuracy (e.g., bench rest shooting, where that rate of fire is low enough that barrel heating is not a major issue) for at least two centuries, and they work very well in that regard.
The strain is concentrated at or near the chamber, can we agree on that? I get that the stiffness is reduced at the point where the material is removed, but the strain is far, far less at the muzzle, and the deleted material will reduce strain at the base where it's most concentrated. Same reason a flag pole is tapered.
Therefore, the tapered barrel will not deflect more than a non tapered one. Not due to barrel whip, or even due to loading in the case of a non free floated barrel. Reducing stiffness at an area where there's less strain does not reduce the overall stiffness of the barrel with regard to how it's stressed. In other words, it effectively increases the stiffness of the barrel.
And yes I get that that's not the definition of stiffness but that's what people mean when they talk about the stiffness or rigidity of a barrel, which you obviously know good and well and are just here to harass me but whatever. Apparently I'm the resident whipping boy now so have at it.
Less mass, given the same impulse, will move more, faster.
And your original claim was that removing material can make an object more rigid. With a tapered barrel, area of flex that has the most impact is at the base, thats why preference is to have thicker material there... its more rigid/stiff.
Flag poles are tapered for reasons related to wind harmonics and not related to the discussion at hand.
Less mass, given the same impulse, will move more, faster.
And your original claim was that removing material can make an object more rigid. With a tapered barrel, area of flex that has the most impact is at the base, thats why preference is to have thicker material there... its more rigid/stiff.
Flag poles are tapered for reasons related to wind harmonics and not related to the discussion at hand.
I'm sure by now we've all seen the slow motion footage of what heavy muzzle brakes and silencers do to barrels. More weight at the end of a barrel doesn't do good things. We also know that a recce profile handles silencers better than a government profile, and that government profile is similar to a pencil profile in terms of not being great for mounting silencers. We also know what would happen if you put a heavy weight at the top of a flagpole; it would gallop back and forth like mad. I think the analogy works.
My original claim was a response to someone who was obviously using the term in its colloquial sense and not the textbook definition. When people talk about a barrel's rigidity they're talking about the degree to which it deflects under a given load.
First "strain" is directly proportional to the amount of deformation experienced by an object under loading. Therefore, it is not concentrated at or near the chamber, but where the barrel sees the highest bending, say in between nodes?
So, you might want to rethink that last statement.
Short argument, people have been making bull barrels for low rate fire accuracy (e.g., bench rest shooting, where that rate of fire is low enough that barrel heating is not a major issue) for at least two centuries, and they work very well in that regard.
Well if you were to clamp an upper in a vise (pretend the flange isn't the weak point) and start hanging weight off of it, it would almost certainly eventually snap off at the barrel extension. And if you watch high speed of a barrel whipping (assuming it's not a light profile) the point where it's flexing looks to be somewhere down near the receiver.
Google "broken flag pole" and see how many of them are bent or broken off at the tip, where they have the least rigidity. None. They break or bend at or near the base where they have the most rigidity. Increasing rigidity at the tip wouldn't change that. It would be counterproductive, as the additional weight would just increase the load without making the system any more rigid than it was before.
One thing I don't think you guys are considering is that the barrel wall is thinner at the chamber on a bull barrel than it is anywhere else. The wall at the muzzle on a bull barrel is like .375 and only maybe half that around the chamber. Shaving some material towards the muzzle will in no way whatsoever make the system less rigid than it was before. There's almost no strain in that area and it's almost twice as thick to begin with. Shaving material there can only help.
1) You are confusing "strain" with "stress". High stress may exceed the yield strength and fail a beam, but it doesn't automatically mean that it moves a lot before failing.
2) A flagpole is not required to have maximum "rigidity". A flag pole is designed to tall, and have a varying force at, or near the top, not fall over, and to be light and cheap as possible. Flag poles are actually quite flexible.
3) Again, there is almost no bending strain anywhere, because there is no measurable deformation of the material There is higher bending stress at the breech end, but stress does not mean deformation. Google "flagpole in the wind" and tell me they are anything like "rigid". And further, you will note that flagpoles in the wind bend more the higher you go, they bend more as stiffness decreases. Then you have the old fashion pine-log telephone pole, these are "bull" profile, are subjected to the same wind loads as a flagpoles, have additional loads from the wire tension in various directions, and do not snap off under normal conditions.
4) And harmonics. The stiffer a beam, the natural frequency will be higher, with a higher frequency, the same input energy will result in lower vibratory amplitude, i.e., less movement.
And last, deflection at the muzzle may or may not be bad, consistency is what we want. As long as the deflection is the same direction, angle and magnitude, we can compensate for it. Which why you can make a very accurate tapered barrel. But, it much easier if the barrel is as stiff as possible.
If I may suggest some reading:
Engineering Mechanics: Statics & Dynamics (https://www.abebooks.com/9780395142080/Engineering-Mechanics-Statics-Dynamics-D.K-0395142083/plp) and Mechanics of Materials (https://www.amazon.com/Mechanics-Materials-James-M-Gere/dp/0534934293)
1) You are confusing "strain" with "stress". High stress may exceed the yield strength and fail a beam, but it doesn't automatically mean that it moves a lot before failing.
2) A flagpole is not required to have maximum "rigidity". A flag pole is designed to tall, and have a varying force at, or near the top, not fall over, and to be light and cheap as possible. Flag poles are actually quite flexible.
3) Again, there is almost no bending strain anywhere, because there is no measurable deformation of the material There is higher bending stress at the breech end, but stress does not mean deformation. Google "flagpole in the wind" and tell me they are anything like "rigid". And further, you will note that flagpoles in the wind bend more the higher you go, they bend more as stiffness decreases. Then you have the old fashion pine-log telephone pole, these are "bull" profile, are subjected to the same wind loads as a flagpoles, have additional loads from the wire tension in various directions, and do not snap off under normal conditions.
4) And harmonics. The stiffer a beam, the natural frequency will be higher, with a higher frequency, the same input energy will result in lower vibratory amplitude, i.e., less movement.
And last, deflection at the muzzle may or may not be bad, consistency is what we want. As long as the deflection is the same direction, angle and magnitude, we can compensate for it. Which why you can make a very accurate tapered barrel. But, it much easier if the barrel is as stiff as possible.
If I may suggest some reading:
Engineering Mechanics: Statics & Dynamics (https://www.abebooks.com/9780395142080/Engineering-Mechanics-Statics-Dynamics-D.K-0395142083/plp) and Mechanics of Materials (https://www.amazon.com/Mechanics-Materials-James-M-Gere/dp/0534934293)
If you watch high speed footage of a heavy-ish barrel whipping it most certainly is the result of measurable deformation of the material. And especially in the case of a precision bolt action you can't attribute that to the receiver flexing like you could with an AR. The fact is that even heavy barrels DO deform under recoil, and the largest deformation happens somewhere close to the chamber.
My understanding of strain is that it's a geometrical measurement and stress is a measure of force. Is that not correct?
ETA: And yes obviously a stiff barrel is better but increasing stiffness at the area with the least strain (I believe I'm using that term correctly) is not going to help anything. It's only going to increase the inertia and increase the stress placed on the area that's already the weak link in the system. I.e. when the gun recoils back and up, the barrel's inertia wants to remain at rest, causing the barrel to deflect (reason why silencers and heavy brakes increase whip).
https://i.imgur.com/VKhXt4J.png
https://i.imgur.com/iZbuMnF.png
https://i.imgur.com/9uvdbwe.png
Note that I didn't reduce the load on the tapered barrel. In real life there's significantly less inertia and therefore significantly less force. Not to mention the reduction of mass is in the most critical area in terms of reducing the strain at the base.
The mass was reduced by almost 40%, most of it at the end, so I'm just off the top of my head guestimating that might well reduce the force by half or more.
https://i.imgur.com/80MGlJG.png
https://i.imgur.com/Uy1gSpp.png
In the unfluted version the strain and stress were concentrated in the same area. With the exaggerated fluting the stress was concentrated at the flutes, but the strain was still concentrated at the base.
Fluting reduced weight by about another 20% (obviously that's way more extreme than any production barrel), and it increased surface area by about 10%. Most of the weight reduction was in the rear where it's less significant, and the loss of thermal mass was pretty extreme compared to the gain in surface area.
Do you know what those pretty pictures show you, in regards to accuracy?
Nothing.
What does reduced stress (or strain) at the root have to do with deflection at the muzzle?
Again, nothing.
Deflection at the muzzle is governed by the loads created by the bullet moving down the bore, and the inflation of the barrel behind the bullet. Deflection can be calculated, however, if the loads are the same, the barrel material is the same, the length is the same, and root diameter are the same the equations will boil down to:
Deflection = Constant/I
We know I of a straight barrel is greater than any barrel profile that removes material from the straight profile, so what happens you make a denominator smaller?
That's right the deflection will get bigger.
Your pictures show the two barrels under the same deflection, so yes, you did reduce the load on the tapered barrel. If the loads were the same the stress at the breech would be the same.
The stress in a bending beam can be expressed as
σ = y M / I
where
σ = stress at a point (x) along the beam's length
y = distance to point from neutral axis (in this case it will be the radius to the outside of the barrel at point x)
M = bending moment at a point (x) along the beam's length
I = moment of Inertia at point (x)
-OR-
σ = y F L / I
The stress at the breech end will be the highest, so that is the location of x if we want the maximum stress.
Again the material is the same (E = constant), length is the same (L = constant), and the force is the same (so, F = constant, and by extension the moment M = constant). And, further in this case we only need the I at the point of interest (x) which in this case is the maximum diameter at the breech, which is the same for both barrels, ergo the stress is the same.
For the same deflection, the tapered barrel will have lower stress at the fixed end. But, since the loads are what is constant, the constant deflection scenario tells us nothing.
For the equations, here (https://www.engineeringtoolbox.com/cantilever-beams-d_1848.html).
Run some Cialis down that barrel.
Do you know what those pretty pictures show you, in regards to accuracy?
Nothing.
What does reduced stress (or strain) at the root have to do with deflection at the muzzle?
Again, nothing.
Deflection at the muzzle is governed by the loads created by the bullet moving down the bore, and the inflation of the barrel behind the bullet. Deflection can be calculated, however, if the loads are the same, the barrel material is the same, the length is the same, and root diameter are the same the equations will boil down to:
Deflection = Constant/I
We know I of a straight barrel is greater than any barrel profile that removes material from the straight profile, so what happens you make a denominator smaller?
That's right the deflection will get bigger.
Your pictures show the two barrels under the same deflection, so yes, you did reduce the load on the tapered barrel. If the loads were the same the stress at the breech would be the same.
The stress in a bending beam can be expressed as
σ = y M / I
where
σ = stress at a point (x) along the beam's length
y = distance to point from neutral axis (in this case it will be the radius to the outside of the barrel at point x)
M = bending moment at a point (x) along the beam's length
I = moment of Inertia at point (x)
-OR-
σ = y F L / I
The stress at the breech end will be the highest, so that is the location of x if we want the maximum stress.
Again the material is the same (E = constant), length is the same (L = constant), and the force is the same (so, F = constant, and by extension the moment M = constant). And, further in this case we only need the I at the point of interest (x) which in this case is the maximum diameter at the breech, which is the same for both barrels, ergo the stress is the same.
For the same deflection, the tapered barrel will have lower stress at the fixed end. But, since the loads are what is constant, the constant deflection scenario tells us nothing.
For the equations, here (https://www.engineeringtoolbox.com/cantilever-beams-d_1848.html).
You're missing the point entirely. The point is that the chamber is the weak link in the system, and that with respect to barrel deflection you can strategically remove a certain amount of material without negatively impacting what people refer to as the barrel's rigidity.
I did not reduce the load on the tapered barrel. Both barrels have the same constraint and the same load in the same location along their length. The highest strain is at the barrel extension on both, and the deflection was the same for both.
You're missing the point entirely.
You are the one missing the point here.
You need to shoot more (of the stuff you are trying to 'inform' us all about) and spend less time on the internet and playing on your computer.
You are the one missing the point here.
You need to shoot more (of the stuff you are trying to 'inform' us all about) and spend less time on the internet and playing on your computer.
Okay, explain it to me then.
You're missing the point entirely. The point is that the chamber is the weak link in the system, and that with respect to barrel deflection you can strategically remove a certain amount of material without negatively impacting what people refer to as the barrel's rigidity.
I did not reduce the load on the tapered barrel. Both barrels have the same constraint and the same load in the same location along their length. The highest strain is at the barrel extension on both, and the deflection was the same for both.
You really have no understanding of the mechanic of materials. You really need to read those two books, so you can actually know something about what you are trying to talk about.
1) People's definition of "rigidity" is an object's resistance to bending. We have shown you over and over that rigidity is governed by the 2nd moment of area, and anything that reduces the cross sectional area reduces rigidity, period.
2) The chamber is not "the weak link," if you knew anything about cantilever beams, you would know that the fixed end will always have the highest stress. And, if you knew anything about vibrating beams you would know that the fixed end is not that important, as long as the stresses are within the material's strength.
3) Yes, you did reduce the force, because it is obvious that the deflection of the centerlines of the bores are the same. The tapered barrel has a muzzle 1/2 the diameter of the breech end and the bull barrel is the breech diameter all the way down, both barrels have bores that are approximately 1/4 the breech end diameter.
The top of the tapered barrel is pushed down so that the top is just under the bottom of the undeflected position, so that puts the centerline of the bore one-half a breech diameter below its original position. The bull barrel is pushed down so the top of the barrel is at the centerline of the undeflected bore, so the centerline of the bore is one-half a breech diameter below its undeflected position.
We have proven that a reduction in the moment of inertia will result in increase in deflection, and given its a straight taper we know the moment of inertia relative to the bull profile. A straight tapered tube such as that shown has an I that is about 75% of the I of a straight tube of the same outside and inside diameter. So if you go back to the deflection equation in post #67, for the same load, material, etc., the taper tube should deflect down 1-1/3 more than the bull barrel. While the scale is not exact, 130% more deflection would be obvious, and it's not there.
(And, if you changed the scale and magnification between the two, then nobody can tell anything from those pictures, as nothing is labeled, there is no indication of what the applied force is, and the maximum and minimum stresses are, other than the color scale, which is way to coarse a scale to determine anything.)
You are the one missing the point here.
You need to shoot more (of the stuff you are trying to 'inform' us all about) and spend less time on the internet and playing on your computer.
Okay, explain it to me then.
He is saying if you shot more, and really tried to make the most accurate AR possible, instead of trying to "educate" us with stuff you really don’t know anything about, you would know why accurate shooters use barrels like this:
https://i.imgur.com/LTsLcfq.png
https://i.imgur.com/XKisnCc.png
Images courtesy Molon
He is saying if you shot more, and really tried to make the most accurate AR possible, instead of trying to "educate" us with stuff you really don’t know anything about, you would know why accurate shooters use barrels like this:
https://i.imgur.com/LTsLcfq.png
https://i.imgur.com/XKisnCc.png
Images courtesy Molon
Pretty much exactly that.
https://i.imgur.com/Mj2WCvE.jpg
You really have no understanding of the mechanic of materials. You really need to read those two books, so you can actually know something about what you are trying to talk about.
1) People's definition of "rigidity" is an object's resistance to bending. We have shown you over and over that rigidity is governed by the 2nd moment of area, and anything that reduces the cross sectional area reduces rigidity, period.
2) The chamber is not "the weak link," if you knew anything about cantilever beams, you would know that the fixed end will always have the highest stress. And, if you knew anything about vibrating beams you would know that the fixed end is not that important, as long as the stresses are within the material's strength.
3) Yes, you did reduce the force, because it is obvious that the deflection of the centerlines of the bores are the same. The tapered barrel has a muzzle 1/2 the diameter of the breech end and the bull barrel is the breech diameter all the way down, both barrels have bores that are approximately 1/4 the breech end diameter.
The top of the tapered barrel is pushed down so that the top is just under the bottom of the undeflected position, so that puts the centerline of the bore one-half a breech diameter below its original position. The bull barrel is pushed down so the top of the barrel is at the centerline of the undeflected bore, so the centerline of the bore is one-half a breech diameter below its undeflected position.
We have proven that a reduction in the moment of inertia will result in increase in deflection, and given its a straight taper we know the moment of inertia relative to the bull profile. A straight tapered tube such as that shown has an I that is about 75% of the I of a straight tube of the same outside and inside diameter. So if you go back to the deflection equation in post #67, for the same load, material, etc., the taper tube should deflect down 1-1/3 more than the bull barrel. While the scale is not exact, 130% more deflection would be obvious, and it's not there.
(And, if you changed the scale and magnification between the two, then nobody can tell anything from those pictures, as nothing is labeled, there is no indication of what the applied force is, and the maximum and minimum stresses are, other than the color scale, which is way to coarse a scale to determine anything.)
There is no visible deflection in any of those studies. The deflection in the graphic is exaggerated by several orders of magnitude for visual purposes, so that the viewer can see where and how it's happening. There are in fact very small changes in deflection between the different profiles, but they're measured in microns. The load was not changed. I left constraints and loads alone and simply reran the study after making profile changes to the model.
So when I say the deflection was the same I mean that it was practically speaking the same (as in the difference is so small you will never be able to actually quantify it in group size). There was about a 20 micron difference at the extreme end.
This study also did not take into account the fact that there's less load on the lighter barrel because it has less inertia. When the rifle recoils and the barrel accelerates upwards the barrel's inertia causes it to deform. Again, that's why large, heavy muzzle devices are associated with increased barrel whip. So what I'm demonstrating is that the rigidity of the barrel is practically unchanged, but that in actual use deflection would be reduced due to the lower inertia.
In gun jargon, a barrel's rigidity simply refers to how well it resists deflecting. That's why people say things like shorter barrels are more rigid. Yes, I get it, that's not the literal definition, but that's how it's commonly used, and I'm sure that's how the subject of this little debate from Knight's was using it. Again, you well know this obviously and are simply trolling at this point. We get it. The barrel is technically less rigid from the literal standpoint, but NOT from the standpoint in which the jargon is used. If you want different terminology then fine, we'll say that the loss of rigidity is negligible and that deflection is reduced through the loss of inertia.
Again, those bull barrels are popular in bench and varmint because they hold their bore diameter longer. And they're used by people who don't have to carry them. Rigidity is a VERY small part of a gun's accuracy. The barrel of any gun does not perceptibly deflect until the bullet leaves the muzzle. Theoretically there is a very, very small amount of deflection prior to the bullet leaving the muzzle, but it's a very small factor compared to maintaining the diameter of the bore, especially at the crown. In other words, if a bull barrel deflects a little bit more than an HBAR it's an immeasurably small price to pay for the increased thermal mass and surface area, which is dramatic. Assuming you don't have to carry it or shoot it offhand, a bull barrel will always outshoot any other profile if both barrels are shot at the same rate of fire, because the bull barrel will stay several times cooler, particularly at the muzzle.
You really have no understanding of the mechanic of materials. You really need to read those two books, so you can actually know something about what you are trying to talk about.
1) People's definition of "rigidity" is an object's resistance to bending. We have shown you over and over that rigidity is governed by the 2nd moment of area, and anything that reduces the cross sectional area reduces rigidity, period.
Yea see that's the whole issue we're having right there. Because that's not how it's used to describe barrels. When people say shorter barrels are more rigid or fluting increase rigidity, they're talking about how much the barrel bends when it's actually fired. Everybody gets that if you bend the barrel over your knee that the tapered or fluted barrel will bend slightly more than the bull barrel. I'm not disputing that.
But what you're not getting (or just choosing to ignore) is that's not how barrels are stressed when you shoot them (with the exception of loading at the handguard or bipod, but that's a whole different topic). Increasing rigidity in an area of low stress that's not going to deflect anyways isn't going to do anything but add more inertia and therefore actually increase the stress placed on the weakest part. As you go out the length of the barrel, the stress falls off, but the impact of the stress that additional material has on the chamber area increases.
Yea see that's the whole issue we're having right there. Because that's not how it's used to describe barrels. When people say shorter barrels are more rigid or fluting increase rigidity, they're talking about how much the barrel bends when it's actually fired. Everybody gets that if you bend the barrel over your knee that the tapered or fluted barrel will bend slightly more than the bull barrel. I'm not disputing that.
But what you're not getting (or just choosing to ignore) is that's not how barrels are stressed when you shoot them (with the exception of loading at the handguard or bipod, but that's a whole different topic). Increasing rigidity in an area of low stress that's not going to deflect anyways isn't going to do anything but add more inertia and therefore actually increase the stress placed on the weakest part. As you go out the length of the barrel, the stress falls off, but the impact of the stress that additional material has on the chamber area increases.
Two things, the places you say don't bend, actually do bend. The barrel vibrates at multiple frequencies, however the primary frequency of vibration is going to be the natural frequency of the barrel. This can be calculated and you will find that the higher the I, or to say, the stiffer the barrel, the higher the natural frequency. The for a fixed energy input, higher the frequency something vibrates at, the lower the amplitude. But, that is not the only benefit of a stiffer barrel, the stiffer the barrel, all frequencies will see reduced amplitude.
Second thing, that you really don't seem to grasp is that stress all by itself has nothing to do with this topic. Stress is the result of bending, not the cause. Bending is the result of the forces generated by the bullet being forced down the barrel and the inflation of the barrel behind the bullet, both of which are moving down the barrel. Due to this very complex force function, the barrel will flex, bend, whip, and vibrate in a very complex manner, as long as the stress does not exceed the strength limits of the barrel material, their magnitude is of no interest.
Increasing stiffness, with all other forces and materials remaining the same, will reduce barrel motion, because that's what the math says will happen.
There is no visible deflection in any of those studies. The deflection in the graphic is exaggerated by several orders of magnitude for visual purposes, so that the viewer can see where and how it's happening. There are in fact very small changes in deflection between the different profiles, but they're measured in microns. The load was not changed. I left constraints and loads alone and simply reran the study after making profile changes to the model.
So when I say the deflection was the same I mean that it was practically speaking the same (as in the difference is so small you will never be able to actually quantify it in group size). There was about a 20 micron difference at the extreme end.
Assuming the barrel is 20 inches long, a 20 micron deflection will result in a 0.140" dispersion at 100 yards. Bench rest competitions are won or lost over smaller dispersion.
This study also did not take into account the fact that there's less load on the lighter barrel because it has less inertia. When the rifle recoils and the barrel accelerates upwards the barrel's inertia causes it to deform. Again, that's why large, heavy muzzle devices are associated with increased barrel whip. So what I'm demonstrating is that the rigidity of the barrel is practically unchanged, but that in actual use deflection would be reduced due to the lower inertia.
In gun jargon, a barrel's rigidity simply refers to how well it resists deflecting. That's why people say things like shorter barrels are more rigid. Yes, I get it, that's not the literal definition, but that's how it's commonly used, and I'm sure that's how the subject of this little debate from Knight's was using it. Again, you well know this obviously and are simply trolling at this point. We get it. The barrel is technically less rigid from the literal standpoint, but NOT from the standpoint in which the jargon is used. If you want different terminology then fine, we'll say that the loss of rigidity is negligible and that deflection is reduced through the loss of inertia.
Now, you are introducing inertia, and in order to make the supposition you are making you need to know the exact magnitude and duration of the forces in order to ascertain if the forces impart sufficient momentum to the overcome the added stiffness of the more massive barrel.
Since we do not actually know the forces' magnitude and duration, we cannot calculate an answer and have to go look at empirical evidence, Empirical evidence shows bull barrels work as advertised. So unless you have empirical evidence to the contrary, or a good model of the forces on a barrel and can show, mathematically, otherwise, I will stick with the hypothesis that you're wrong.
Again, those bull barrels are popular in bench and varmint because they hold their bore diameter longer. And they're used by people who don't have to carry them. Rigidity is a VERY small part of a gun's accuracy. The barrel of any gun does not perceptibly deflect until the bullet leaves the muzzle. Theoretically there is a very, very small amount of deflection prior to the bullet leaving the muzzle, but it's a very small factor compared to maintaining the diameter of the bore, especially at the crown. In other words, if a bull barrel deflects a little bit more than an HBAR it's an immeasurably small price to pay for the increased thermal mass and surface area, which is dramatic. Assuming you don't have to carry it or shoot it offhand, a bull barrel will always outshoot any other profile if both barrels are shot at the same rate of fire, because the bull barrel will stay several times cooler, particularly at the muzzle.
Finally, you supposition that added mass at the muzzle is always bad, plaese explain why and how these work: (and they do work)
https://images.coreware.com/images/products/8296-6423774.jpg
https://www.browning.com/support/faq/boss-system.html
I also think you (okie) are mixing stress and strain, or mixing cause/effect. The barrel is an isolated system so the force is the same, the deflection (strain) will increase, as well as localized stress on a lighter profile or fluted barrel.
Its an impulse down the barrel, not a static load. A tapered barrel removes force if measuring a static load.
On the original topic. I am hardly an expert on CF wrapped barrels, I have one on a .22 bolt gun and only because that's the way it came (Bergara B14).
Forgive me if I am wrong, but here is what I have come to understand over the years. Primary benefit is weight over same diameter steel, CF properties are highly variable dependent on the "recipe" and the application process, CF can conduct heat but never as well as steel, CF can provide stiffness but never exactly as much as steel, CF can create better barrel harmonics in some examples.
My take is that other than weight, it is only worth arguing about if you are looking at very specific criteria in a very well made/controlled sample. Honestly that ain't me. I would be better off spending the coin on practice or training.
Am I mistaken in that CF barrels are largely about the "cool kid" factor? I mean my .22 CF shoots awesome and all but it's primary limiting factor is my skill set. I can't see the CF as a benefit for me, I would be served just as well by steel I'm sure.
Carbon Fiber barrels are best for innagrass shooting because they put off less of a heat signature, making it more difficult for the enemy to find you.
vicious_cb
12-26-22, 21:52
I don't think you people are understanding what you are dealing with here. Okie is the epitome of Dunning-Kruger syndrome who will continually double and triple down on his completely wrong and illogical ideas about things. I had to tear him a new one on Terminal Ballistics with facts and data and he still won't get it. Its like talking to a brick wall this guy, pretty sure he has kind of learning disability.
https://www.m4carbine.net/showthread.php?237285-Which-would-you-choose-given-the-parameters&p=3058311#post3058311
Here is another thread on Colts and someone had to tear him a new on on:
https://www.m4carbine.net/showthread.php?237482-How-is-the-Colt-OEM-recorded-on-the-4473-Is-it-a-candidate-for-being-a-pistol&p=3060617#post3060617
Anyone else seeing a pattern here?
I don't think you people are understanding what you are dealing with here. Okie is the epitome of Dunning-Kruger syndrome who will continually double and triple down on his completely wrong and illogical ideas about things. I had to tear him a new one on Terminal Ballistics with facts and data and he still won't get it. Its like talking to a brick wall this guy, pretty sure he has kind of learning disability.
https://www.m4carbine.net/showthread.php?237285-Which-would-you-choose-given-the-parameters&p=3058311#post3058311
Here is another thread on Colts and someone had to tear him a new on on:
https://www.m4carbine.net/showthread.php?237482-How-is-the-Colt-OEM-recorded-on-the-4473-Is-it-a-candidate-for-being-a-pistol&p=3060617#post3060617
Anyone else seeing a pattern here?
Yes, but were you explaining things innagrass?
I don't think you people are understanding what you are dealing with here. Okie is the epitome of Dunning-Kruger syndrome who will continually double and triple down on his completely wrong and illogical ideas about things. I had to tear him a new one on Terminal Ballistics with facts and data and he still won't get it. Its like talking to a brick wall this guy, pretty sure he has kind of learning disability.
https://www.m4carbine.net/showthread.php?237285-Which-would-you-choose-given-the-parameters&p=3058311#post3058311
Here is another thread on Colts and someone had to tear him a new on on:
https://www.m4carbine.net/showthread.php?237482-How-is-the-Colt-OEM-recorded-on-the-4473-Is-it-a-candidate-for-being-a-pistol&p=3060617#post3060617
Anyone else seeing a pattern here?
Don't forget this gem.
https://www.m4carbine.net/showthread.php?233971-Am-I-the-only-one-starting-to-prefer-iron-sights/page24
The origin of "innagrass"
vicious_cb
12-26-22, 23:44
Don't forget this gem.
https://www.m4carbine.net/showthread.php?233971-Am-I-the-only-one-starting-to-prefer-iron-sights/page24
The origin of "innagrass"
Thanks! Guess I missed that $hitshow.
Glad I missed most of this one while OCONUS.
titsonritz
12-27-22, 00:36
Don't forget this gem.
https://www.m4carbine.net/showthread.php?233971-Am-I-the-only-one-starting-to-prefer-iron-sights/page24
The origin of "innagrass"
That one is a classic.
Assuming the barrel is 20 inches long, a 20 micron deflection will result in a 0.140" dispersion at 100 yards. Bench rest competitions are won or lost over smaller dispersion.
Now, you are introducing inertia, and in order to make the supposition you are making you need to know the exact magnitude and duration of the forces in order to ascertain if the forces impart sufficient momentum to the overcome the added stiffness of the more massive barrel.
Since we do not actually know the forces' magnitude and duration, we cannot calculate an answer and have to go look at empirical evidence, Empirical evidence shows bull barrels work as advertised. So unless you have empirical evidence to the contrary, or a good model of the forces on a barrel and can show, mathematically, otherwise, I will stick with the hypothesis that you're wrong.
Finally, you supposition that added mass at the muzzle is always bad, plaese explain why and how these work: (and they do work)
https://images.coreware.com/images/products/8296-6423774.jpg
https://www.browning.com/support/faq/boss-system.html
Barrel whip is caused by multiple things. The vibration of the bullet engaging the rifling and the inertia of the barrel during recoil. If inertia were of no consequence then you could put a big heavy silencer on a government barrel and like you asserted earlier it would actually help dampen. And were the vibration from the bullet the only source of barrel movement, that would be the case.
I'm not familiar with that device but it looks to be a way to tune the barrel's harmonics. I.e. make it so that the bullet of your choice is leaving the barrel at a moment when it's at minimum deflection. It's not a dampening device like you think. Tuning devices simply adjust the wavelength slightly so you can play with them until all your bullets are going through the same hole. Otherwise you have bullets leaving the barrel in a vortex pattern. It's the same thing as shimming a non floated barrel, or tensioning the front band on an M25 or similar (or using the tuning screw on the Mk14). By adjusting the tension you can adjust the harmonics to play nice with whatever ammo you're using. That's what people are talking about when they say their gun "likes" a certain ammo. They're saying that that particular ammo is naturally copacetic with their barrel. Using a tuning system of some kind you can make your gun "like" whatever ammo you want.
The 20 micron deflection isn't the actual deflection at the point the bullet leaves the barrel. That's just comparing deflection under static load cases to demonstrate that various heavy profiles have negligible differences in rigidity. Again, the barrel does not perceptibly move until after the bullet leaves. It's theoretically accepted that the barrel must move slightly but to my knowledge nobody has ever measured it. Trying to build a model to determine actual deflection at various profiles would be a NASA level undertaking. Not to mention one would need lots of data we don't have, and you're most certainly not going to be able to create that kind of simulation in Solidworks or Inventor anything else any of us here have access to.
Also, this isn't my opinion. I'm repeating what was told to me by the owner of a custom barrel maker you would recognize, that supplies a lot of high level match shooters. He's the one who educated me to the fact that rigidity doesn't have much impact but thermal mass does. He said a thin profile will shoot as good as anything else if it's free floated, provided you shoot slow enough so it doesn't get hot. Everything I've learned since has proved him right. "Rigidity" is a very, very small part of what makes a barrel accurate. But barrels that people perceive as being very rigid, despite not being much more rigid in practice than a much lighter profile, have significantly more thermal mass and surface area, and that makes a world of difference in holding groups.
vicious_cb
12-27-22, 02:33
I'm not familiar with that device but it looks to be a way to tune the barrel's harmonics. I.e. make it so that the bullet of your choice is leaving the barrel at a moment when it's at minimum deflection. It's not a dampening device like you think. Tuning devices simply adjust the wavelength slightly so you can play with them until all your bullets are going through the same hole. Otherwise you have bullets leaving the barrel in a vortex pattern. It's the same thing as shimming a non floated barrel, or tensioning the front band on an M25 or similar (or using the tuning screw on the Mk14). By adjusting the tension you can adjust the harmonics to play nice with whatever ammo you're using. That's what people are talking about when they say their gun "likes" a certain ammo. They're saying that that particular ammo is naturally copacetic with their barrel. Using a tuning system of some kind you can make your gun "like" whatever ammo you want.
This is why everyone says you talk out of your a$$, because you have zero real world experience about everything you talk about.
Anyone who has shot air rifles, pellet guns or BB rifles would recognize what that object in the picture is that that they actually work and Im not even a barrel engineer.
You realize you are just digging yourself deeper into the hole with every post you make about how ignorant you are about pretty much every subject you claim to know so much about right?
I mean do we really need to get to the point where a mod has to step in for the nth time because you've embarrassed yourself so much?
It's theoretically accepted that the barrel must move slightly but to my knowledge nobody has ever measured it.
Actually, not only the magnitude of the movement, but the velocity has been measured. And further, it has shown that a big heavy bull profile barrel moves very little.
Accuracy and Jump Measurements of the 5.56mm M855 Cartridge (https://apps.dtic.mil/sti/citations/ADA542434)
I am starting to have flashbacks when this guy posts. He always comes back for the last word and/or to keep the thread going. Anyone remember Gecko 45? AKA THE MALL NINJA.
For the young guys, it’s an inside joke. For us old guys, it was a classic.
Cheers, Steve
I have said this before, but I really think okie is a masterful troll.
vicious_cb
12-27-22, 13:22
I have said this before, but I really think okie is a masterful troll.
Then the mods should just ban him then.
Then the mods should just ban him then.
Perhaps. I've stopped taking him seriously, so to me he's actually pretty entertaining. The machinations he goes through to justify his erroneous thinking (assuming he's not trolling and genuinely believes what he says) are fascinating. OTOH, if he is trolling (as I suspect) he's a genius at it. Fascinating to watch from either perspective.
Perhaps. I've stopped taking him seriously, so to me he's actually pretty entertaining. The machinations he goes through to justify his erroneous thinking (assuming he's not trolling and genuinely believes what he says) are fascinating. OTOH, if he is trolling (as I suspect) he's a genius at it. Fascinating to watch from either perspective.
The guy is a fountain of misinformation. It's pretty incredible really.
titsonritz
12-27-22, 18:06
The guy is a fountain of misinformation. It's pretty incredible really.
It is spewing out of every orifice.
Here are some more legendary gems.
https://www.m4carbine.net/showthread.php?233307-Viability-of-converting-M4s-to-semi-auto
https://www.m4carbine.net/showthread.php?226512-Has-anyone-ever-seen-a-drop-in-BB-conversion-for-AR-15s
https://www.m4carbine.net/showthread.php?231707-Referencing-the-dunning-kruger-effect-when-arguing-with-people-on-the-internet-is
vicious_cb
12-27-22, 21:26
Perhaps. I've stopped taking him seriously, so to me he's actually pretty entertaining. The machinations he goes through to justify his erroneous thinking (assuming he's not trolling and genuinely believes what he says) are fascinating. OTOH, if he is trolling (as I suspect) he's a genius at it. Fascinating to watch from either perspective.
Its not entertaining spreading complete BS on the internet. Think of all the new shooters and AR owners who don't know any better mistaking his BS for fact because its packaged in such a way it could be misconstrued as having a scientific justification when in reality its just pseudo scientific pontifications on $hit he doesnt even understand. There's a reason why people like me or Lysander take the time to dismantle his arguments and make him look like a clown because the $hit he spews could cause real harm and cost people real money if they think the $hit he says is real.
The talk that occurs near gun counters comes to mind.
Here are some more legendary gems.
https://www.m4carbine.net/showthread.php?233307-Viability-of-converting-M4s-to-semi-auto
https://www.m4carbine.net/showthread.php?226512-Has-anyone-ever-seen-a-drop-in-BB-conversion-for-AR-15s
https://www.m4carbine.net/showthread.php?231707-Referencing-the-dunning-kruger-effect-when-arguing-with-people-on-the-internet-is
The thread about having a class 3 SOT dealer order a real M4 then destroy the receiver so you can harvest the FCG parts and install them in an Aero lower and have a "rEaL MiLsPeC riFLe" is mind numbing.
I also think you (okie) are mixing stress and strain, or mixing cause/effect. The barrel is an isolated system so the force is the same, the deflection (strain) will increase, as well as localized stress on a lighter profile or fluted barrel.
Its an impulse down the barrel, not a static load. A tapered barrel removes force if measuring a static load.
I didn't change the load case for any of the profiles. I realize that's an imperfect model, but it serves the purpose just fine, which is to demonstrate that only a minute amount of rigidity is lost when going from a full bull to another heavy profile. Yes, the bullet going down the barrel I admit does stress the entirety of the barrel's length, however the fact remains that the constraint is always at the chamber (assuming the barrel is free floated). In the real world the difference will be even less because we all know the receiver flexes quite a bit, as well, meaning the already inconsequential difference will be even more so.
Therefore, a static load distributed throughout the barrel's length is a reasonable way to compare the inherent rigidity of each profile. I.e. if it's rigid under a static load it's also going to be rigid with respect to a bullet going down it because the basic proposition is the same in that you have a force trying to deform the barrel that's constrained in the same way, with one end constrained and the other not. But as I've pointed out several times and I think pretty much everyone knows to be true is that the bullet going down the barrel is not the sole source of stress. So my load case is extremely generous to the opposition's argument, because in fact the tapered barrel has far less loading due to inertia.
If I were being more generous to my own argument I would calculate the load using the barrel's weight. I could for example use high speed footage to guestimate the distance, time, and vector. I don't have time to do that for shits and giggles, and for another thing we all know what the result would be. If the difference in deflection was inconsequential under a static load then obviously the tapered barrel would deflect less if the load on it were less. While I can't prove how much barrel whip is the result of vibration and how much is the result of recoil, the affect of heavy muzzle devices at least suggests that recoil is a very large part of that equation.
This is why everyone says you talk out of your a$$, because you have zero real world experience about everything you talk about.
Anyone who has shot air rifles, pellet guns or BB rifles would recognize what that object in the picture is that that they actually work and Im not even a barrel engineer.
You realize you are just digging yourself deeper into the hole with every post you make about how ignorant you are about pretty much every subject you claim to know so much about right?
I mean do we really need to get to the point where a mod has to step in for the nth time because you've embarrassed yourself so much?
I didn't say it didn't work. Go back and read to comprehend.
Actually, not only the magnitude of the movement, but the velocity has been measured. And further, it has shown that a big heavy bull profile barrel moves very little.
Accuracy and Jump Measurements of the 5.56mm M855 Cartridge (https://apps.dtic.mil/sti/citations/ADA542434)
So they're talking about a mann barrel, which almost presupposes that the action is not only clamped in a fixture, but also that it's probably not even an AR upper. Meaning no muzzle flip, meaning no deformation due to acceleration. In which case yes, the additional weight at the end of the muzzle would in fact be beneficial. It would effectively create an additional node of constraint, and the heavier it got the more effective it would become, at least up to a point.
I have said this before, but I really think okie is a masterful troll.
In a time of universal deceit, telling the truth is a revolutionary act.
vicious_cb
12-28-22, 01:27
In a time of universal deceit, telling the truth is a revolutionary act.
You should know, you are adding to the BS pile everytime you type.
I didn't change the load case for any of the profiles. I realize that's an imperfect model, but it serves the purpose just fine, which is to demonstrate that only a minute amount of rigidity is lost when going from a full bull to another heavy profile. Yes, the bullet going down the barrel I admit does stress the entirety of the barrel's length, however the fact remains that the constraint is always at the chamber (assuming the barrel is free floated). In the real world the difference will be even less because we all know the receiver flexes quite a bit, as well, meaning the already inconsequential difference will be even more so.
If you did not change the load, the the stress at the root would be exactly the same for both barrels if both barrels have the same root diameter and length. Physics says so. Physics also says that if the loads are the same and the root diameter and length are the same, the tapered barrel will deflect about 33% more.
Therefore, a static load distributed throughout the barrel's length is a reasonable way to compare the inherent rigidity of each profile. I.e. if it's rigid under a static load it's also going to be rigid with respect to a bullet going down it because the basic proposition is the same in that you have a force trying to deform the barrel that's constrained in the same way, with one end constrained and the other not. But as I've pointed out several times and I think pretty much everyone knows to be true is that the bullet going down the barrel is not the sole source of stress. So my load case is extremely generous to the opposition's argument, because in fact the tapered barrel has far less loading due to inertia.
1) Only you have yet to show that a tapered barrel is more rigid. Show some math that proves your supposition.
2) Stress, force, and deflection are three different things, They are related to each other, but you keep using them if they were synonymous. That's one of the major problems in your logic.
3) There are three sources force on a barrel - the bullet being squeezed down the bore, the pressure inflating the barrel behind it, and inertial forces due to recoil motion. If you think there are more, please name them.
4) Without knowing the magnitude of the forces, you cannot know the magnitudes of the inertial loads. In order to back up that last sentence, you are going to have to provide a force function on the two different barrel profiles and show, with some math what you say is true.
5) And I assume that when you say "generous to the opposition's argument" you mean "we are going to ignore all the math and physics that prove I am mistaken",because that's what you are doing. I have yet to see anything based in physics, mechanics of materials, or any form of engineering, that supports your logic.
(And once again, stresses are a result of forces and deflection, not the cause.)
If I were being more generous to my own argument I would calculate the load using the barrel's weight. I could for example use high speed footage to guestimate the distance, time, and vector. I don't have time to do that for shits and giggles, and for another thing we all know what the result would be. If the difference in deflection was inconsequential under a static load then obviously the tapered barrel would deflect less if the load on it were less. While I can't prove how much barrel whip is the result of vibration and how much is the result of recoil, the affect of heavy muzzle devices at least suggests that recoil is a very large part of that equation.
Major problem with your logic.
You are assuming that the static load from gravity is in the same order of magnitude as the dynamic loads on the barrel, which can be estimated from the information in that report. And, they aren't anywhere close, the dynamic loads are high, very high.
And last, you keep saying the stiffness at the end of the barrel doesn't matter, and I can show you why without "complicated" math stiffness out there does matter:
https://i.imgur.com/FGNtGF0.jpg
The motion of the barrel is a complicated combination of all the vibratory waveforms, with multiple bend points along the length of the barrel, any reduction in stiffness at or near the end of the barrel will allow the bends in that area to increase.
So they're talking about a mann barrel, which almost presupposes that the action is not only clamped in a fixture, but also that it's probably not even an AR upper. Meaning no muzzle flip, meaning no deformation due to acceleration. In which case yes, the additional weight at the end of the muzzle would in fact be beneficial. It would effectively create an additional node of constraint, and the heavier it got the more effective it would become, at least up to a point.
Did you even read the report?
All of the test barrels where clamped in a fixture.
...which is to demonstrate that only a minute amount of rigidity is lost when going from a full bull to another heavy profile.
There it is.
As counterintuitive as it sounds, strategically removing material does increase rigidity by redirecting force vectors.
vicious_cb
12-29-22, 13:08
How convenient that 9-hole reviews just dropped a test of gov't profile vs SOCOM profile hot vs cold accuracy test. Again completely disproving Okie pseudo scientific theories that can't even hold up to high school level physics standards.
https://www.youtube.com/watch?v=aPo6zcGTJ04&t=757s
How convenient that 9-hole reviews just dropped a test of gov't profile vs SOCOM profile hot vs cold accuracy test. Again completely disproving Okie pseudo scientific theories that can't even hold up to high school level physics standard.
https://www.youtube.com/watch?v=aPo6zcGTJ04&t=757s
We mustn't let reality infringe on our assumptions. Doncha know?
By the way, the M4A1 heavy barrel was designed solely to increase the number of rounds before barrel failure. The reason the gas tube was not changed was the "Govt" profile M4 barrel ruptured after about 600 rounds, but the gas tube remained intact (after about 450 rounds the barrel was visibly warped out of shape). The new heavy (SOCOM) barrel lasted over 800 rounds with the gas tube being what failed at 800 rounds.
The Army reasoned that 800 rounds fired as fast as you can was not really that likely, as even the briefest of pauses will allow the gas tube cool enough to carry on . . .
"M4 Carbine Heavy barrel Cook-off," ARDEC, Picatinny Arsenal, NJ
"Fire to Destruction Test of the 5.56mm, M4A1 Carbine and M16A2 Rifle," ARDEC, Rock Island Arsenal, IL.
Here's the video of the M4 vs M4A1 barrel testing. Really incredible to see that M4 barrel droop before failing, and afterwards watch the Socom barrel withstand firing nearly twice as many rounds before the gas tube fails.
https://youtu.be/P9uny8aCoLc
A barrel doesn't actually have to rupture to fail.
This barrel shot 540 rounds and reached a peak temperature of 1,712 F
https://i.imgur.com/DCWDYNg.jpg
Oh, and it only tool 3 minutes to shoot all that ammo.
There it is.
There are various case studies where relief cuts redistributed forces in a way that resulted in less flexing during use.
That might apply to barrel fluting (and I imagine probably does, if done properly). One thing I noticed is that the fluted barrels in my models had increased stress at the base of the flutes but less strain than the unfluted version at that same location.
Did you even read the report?
All of the test barrels where clamped in a fixture.
Then the results don't mean what you think they do.
How convenient that 9-hole reviews just dropped a test of gov't profile vs SOCOM profile hot vs cold accuracy test. Again completely disproving Okie pseudo scientific theories that can't even hold up to high school level physics standards.
https://www.youtube.com/watch?v=aPo6zcGTJ04&t=757s
That supports everything I've been saying this whole time. How did you think those results in any way contradict anything I've said so far???
There are various case studies where relief cuts redistributed forces in a way that resulted in less flexing during use.
That might apply to barrel fluting (and I imagine probably does, if done properly). One thing I noticed is that the fluted barrels in my models had increased stress at the base of the flutes but less strain than the unfluted version at that same location.
Would you mind linking to one of these studies, please?
vicious_cb
01-04-23, 16:03
That supports everything I've been saying this whole time. How did you think those results in any way contradict anything I've said so far???
Keep contradicting yourself bud, I mean if I spouted as much BS as you I would have trouble keeping track of it too.
This completely contradicts this statement, in fact it shows the opposite of your asinine assertion that barrel mass is just there to maintain accuracy under heat stress.
Any barrel will string when it gets hot enough to expand. As I said several times, thicker barrels take a lot longer to heat up, and they dissipate heat faster into the air due to having more surface area. A bull barrel has roughly twice the surface area as a pencil and roughly three times the mass.
From a cold bore, any profiles turned from the same blanks firing the same ammunition will shoot just about the same, but a lighter profile will start to wander within about five shots, whereas a thicker profile might take 20 shots before it gets hot enough to start expanding. The difference between a heavy and light profile AR barrel isn't really relevant to the platform or the way its used, from a rigidity perspective. The whole platform has all kinds of other issues. It's not a precision rifle. You have a barrel slopped into an aluminum receiver and a bolt that doesn't stay square to the chamber when the cartridge is pressurized. Worrying about rigidity in an AR barrel at the expense of thermal mass and heat dissipation is like worrying about the effect of aerodynamics on the acceleration of a minivan.
Then the results don't mean what you think they do.
Yes they tell me exactly what I said they tell me:
You can measure barrel movement, and its effect on dispersion and, a stiffer barrel has less dispersion.
There are various case studies where relief cuts redistributed forces in a way that resulted in less flexing during use.
That might apply to barrel fluting (and I imagine probably does, if done properly). One thing I noticed is that the fluted barrels in my models had increased stress at the base of the flutes but less strain than the unfluted version at that same location.
Show me such a report.
I have linked to two books that state otherwise.
And, you still don't get it (or refuse to), stress and strain are a result of flexing, the more something flexes or bends, the higher the stress and strain. So, your pretty picture is telling you the same thing we are - IT BENDS MORE!
Keep contradicting yourself bud, I mean if I spouted as much BS as you I would have trouble keeping track of it too.
This completely contradicts this statement, in fact it shows the opposite of your asinine assertion that barrel mass is just there to maintain accuracy under heat stress.
So you have a lightweight barrel that outshoots a heavier barrel on a cold bore.
But the heavier barrel outshoots the light barrel once they're heated up. The heavier barrel not only then outshoots the light barrel, but it has less degradation as it heats up.
That's a demonstration of everything I've said up to this point.
Show me such a report.
I have linked to two books that state otherwise.
And, you still don't get it (or refuse to), stress and strain are a result of flexing, the more something flexes or bends, the higher the stress and strain. So, your pretty picture is telling you the same thing we are - IT BENDS MORE!
No. What the computer model told me is that the fluted barrel was flexing less in that specific area.
What the analysis showed is the stress was being redirected along the edges of the flutes into their base where they terminate. Resulting in greater stress but less strain.
vicious_cb
01-04-23, 17:22
So you have a lightweight barrel that outshoots a heavier barrel on a cold bore.
But the heavier barrel outshoots the light barrel once they're heated up. The heavier barrel not only then outshoots the light barrel, but it has less degradation as it heats up.
That's a demonstration of everything I've said up to this point.
Except it didn't...maybe you didn't watch the video or you can't even comprehend basic info given in a easily digestible youtube format? Which is it? Too inept to process information or too lazy to even watch source material either way it proves you are full of it.
...One thing I noticed is that the fluted barrels in my models had increased stress at the base of the flutes but less strain than the unfluted version at that same location.
Assuming under tension: How do you increase stress and reduce strain without yielding the material?
What were the conditions? A static load? Did you fix the load or the bend? What was the fulcrum? Did you simulate an impulse/wave moving down the barrel?
No. What the computer model told me is that the fluted barrel was flexing less in that specific area.
What the analysis showed is the stress was being redirected along the edges of the flutes into their base where they terminate. Resulting in greater stress but less strain.
Once again your failure to grasp even the basics of materials engineering has become glaringly obvious.
Stress and strain are locked together in a relationship via Young's modulus, which is a positive constant for ALL known materials. If stress increases, then strain must follow, and vice versa. It is physically impossible to have greater stress and lower strain.
https://i.imgur.com/NPz4yGb.jpg
If the strain is higher, than so is the stress, ergo, there is more flexing.
Go read some engineering textbooks, and stop embarrassing yourself.
Yes they tell me exactly what I said they tell me:
You can measure barrel movement, and its effect on dispersion and, a stiffer barrel has less dispersion.
You're using a model that completely eliminates all movement of the rifle due to recoil. There's zero acceleration and therefore the inertia of the barrel or anything on the end of it is rendered irrelevant.
vicious_cb
01-04-23, 17:55
Once again your failure to grasp even the basics of materials engineering has become glaringly obvious.
Stress and strain are locked together in a relationship via Young's modulus, which is a positive constant for ALL known materials. If stress increases, then strain must follow, and vice versa. It is physically impossible to have greater stress and lower strain.
https://i.imgur.com/NPz4yGb.jpg
If the strain is higher, than so is the stress, ergo, there is more flexing.
Go read some engineering textbooks, and stop embarrassing yourself.
C'mon man! You're expecting too much from him, he can't even comprehend a very basic youtube video much less an engineering text book.
C'mon man! You're expecting too much from him, he can't even comprehend a very basic youtube video much less an engineering text book.
If you guys are going to gaslight me so hard that you're going to let this stand then we can just stop this right here and now. Nothing in that video refuted anything I've said, and on the contrary confirmed my thesis.
Or how about this. Let's get the engineer from Knights in here who made the original claim that for some bizarre reason has become the entire focus of the thread.
Anybody need grip screws?
vicious_cb
01-04-23, 18:10
If you guys are going to gaslight me so hard that you're going to let this stand then we can just stop this right here and now. Nothing in that video refuted anything I've said, and on the contrary confirmed my thesis.
Or how about this. Let's get the engineer from Knights in here who made the original claim that for some bizarre reason has become the entire focus of the thread.
Gaslighting? You mean calling you out when you try to substitute basic physics, valid sources and clearly presented youtube experiments with your own asinine version of reality? Or do you think it some conspiracy that there are ZERO people here who agree with your version of physics and engineering who are constantly bombarding you with contradictory evidence. We have a name for people who constantly refuse to see reality and try to interject it with their own delusions as per the DSM-5 manual.
No I don't agree with georgeib's assement that you are some masterful troll, I think you need professional help.
Gaslighting? You mean calling you out when you try to substitute basic physics, valid sources and clearly presented youtube experiments with your own asinine version of reality? Or do you think it some conspiracy that there are ZERO people here who agree with your version of physics and engineering who are constantly bombarding you with contradictory evidence. We have a name for people who constantly refuse to see reality and try to interject it with their own delusions as per the DSM-5 manual.
No I don't agree with georgeib's assement that you are some masterful troll, I think you need professional help.
Please explain to me then how anything in that video in any way refutes anything I've said. It CLEARLY demonstrates that what I said is correct, that cold barrels shoot the same regardless of profile, but that heavier barrels hold tighter groups over the course of the same firing schedule as a lighter profile.
Correction. The aforementioned case studies, I was misremembering them. They were about removing material to increase strength, not rigidity. My bad.
The rest I stand by.
You're using a model that completely eliminates all movement of the rifle due to recoil. There's zero acceleration and therefore the inertia of the barrel or anything on the end of it is rendered irrelevant.
Reading is fundamental.
If you actually read what I wrote, read what is in that report on accuracy and muzzle jump, instead of just avoiding the facts, you might actually learn something,
These lines show the change in velocity of the muzzle of the barrel. The definition of "acceleration" is change in velocity. Obviously, not a zero acceleration situation.
https://i.imgur.com/Y3LXkso.jpg
If you read the report, you could learn something about accuracy.
https://i.imgur.com/gADGMiH.jpg
I wonder what that "recoil cylinder" or those springs are for?
Correction. The aforementioned case studies, I was misremembering them. They were about removing material to increase strength, not rigidity. My bad.
The rest I stand by.
Sorry, but removing material always reduces strength, removing material can increase the strength-to-weight ratio, but the maximum strength always goes down, just nowhere near as fast as the weight in a properly designed beam.
I'll be more than happy to see these reports.
Go read some engineering textbooks, and stop embarrassing yourself.
Reading is fundamental.
I suspect that this summarizes this thread.
Sorry, but removing material always reduces strength, removing material can increase the strength-to-weight ratio, but the maximum strength always goes down, just nowhere near as fast as the weight in a properly designed beam.
I'll be more than happy to see these reports.
It's moot anyways because I was misremembering them, and we're off on a giant tangent to begin with. I will just concede that point.
What I would like to talk about more though is that video that Vicious what's his name posted. That's dead on point. The lighter barrel (that we can all agree is a lot less rigid, by any measure) outshot the heavier, more rigid barrel.
But as the barrels heated up, the heavier barrel's accuracy didn't degrade as much, and it actually ended up shooting a slightly tighter group in the end.
So hopefully we can agree that wrapping a light barrel in an insulative material, however rigid, is probably a really bad idea.
It's moot anyways because I was misremembering them, and we're off on a giant tangent to begin with. I will just concede that point.
What I would like to talk about more though is that video that Vicious what's his name posted. That's dead on point. The lighter barrel (that we can all agree is a lot less rigid, by any measure) outshot the heavier, more rigid barrel.
But as the barrels heated up, the heavier barrel's accuracy didn't degrade as much, and it actually ended up shooting a slightly tighter group in the end.
So hopefully we can agree that wrapping a light barrel in an insulative material, however rigid, is probably a really bad idea.
No, because it adds stiffness to the barrel, and with a reasonable rate of fire, heat may not be an issue.
As to the video: The cold barrel group sizes were the same size, and the heavy barrel hot group size was slightly wider, but but approximately the same height as the other hot group.
Since, there are many things that make a barrel shoot tight groups, and we know none of them with these two, we cannot make any statements skinny barrels versus fat barrels absolute accuracy from this video. All we can say is that both barrel opened up after getting hot, and the heavy barrel actually widened up slightly more.
So, your assertion that the only reason for fat barrels is to mitigate increased dispersion due to heat would seem disproven.
However, the best way to prevent heat induced change in POI is 1) proper normalization and stress relieving after forming, and 2) uniformity of material around the bore, both radially and axially. To me the only thing this video tells me is that a hot barrel has greater dispersion than a cold barrel.
vicious_cb
01-05-23, 20:56
It's moot anyways because I was misremembering them, and we're off on a giant tangent to begin with. I will just concede that point.
What I would like to talk about more though is that video that Vicious what's his name posted. That's dead on point. The lighter barrel (that we can all agree is a lot less rigid, by any measure) outshot the heavier, more rigid barrel.
But as the barrels heated up, the heavier barrel's accuracy didn't degrade as much, and it actually ended up shooting a slightly tighter group in the end.
So hopefully we can agree that wrapping a light barrel in an insulative material, however rigid, is probably a really bad idea.
Again you continue to deny the reality set in front of your face and try to replace with your delusions that somehow the video shows the opposite conclusion that you want to prove your point.
Buddy, professional help, you need it.
No, because it adds stiffness to the barrel, and with a reasonable rate of fire, heat may not be an issue.
As to the video: The cold barrel group sizes were the same size, and the heavy barrel hot group size was slightly wider, but but approximately the same height as the other hot group.
Since, there are many things that make a barrel shoot tight groups, and we know none of them with these two, we cannot make any statements skinny barrels versus fat barrels absolute accuracy from this video. All we can say is that both barrel opened up after getting hot, and the heavy barrel actually widened up slightly more.
So, your assertion that the only reason for fat barrels is to mitigate increased dispersion due to heat would seem disproven.
However, the best way to prevent heat induced change in POI is 1) proper normalization and stress relieving after forming, and 2) uniformity of material around the bore, both radially and axially. To me the only thing this video tells me is that a hot barrel has greater dispersion than a cold barrel.
No I don't agree with georgeib's assement that you are some masterful troll, I think you need professional help.
Yeah... Starting to lean your way. The dude is really starting to make me think he's genuinely out of touch. Narcissistic Personality Disorder with delusions of grandeur?
If you guys are going to gaslight me so hard that you're going to let this stand then we can just stop this right here and now. Nothing in that video refuted anything I've said, and on the contrary confirmed my thesis.
That video was not as 'apples to apples' as you seem to think.
One barrel was CHF (not a Colt barrel) and the other was not.
No, because it adds stiffness to the barrel, and with a reasonable rate of fire, heat may not be an issue.
As to the video: The cold barrel group sizes were the same size, and the heavy barrel hot group size was slightly wider, but but approximately the same height as the other hot group.
Since, there are many things that make a barrel shoot tight groups, and we know none of them with these two, we cannot make any statements skinny barrels versus fat barrels absolute accuracy from this video. All we can say is that both barrel opened up after getting hot, and the heavy barrel actually widened up slightly more.
So, your assertion that the only reason for fat barrels is to mitigate increased dispersion due to heat would seem disproven.
However, the best way to prevent heat induced change in POI is 1) proper normalization and stress relieving after forming, and 2) uniformity of material around the bore, both radially and axially. To me the only thing this video tells me is that a hot barrel has greater dispersion than a cold barrel.
Yes, on that we can agree. But hopefully we can also agree that the heavier barrel, had they measured the temperature, would have been significantly cooler than the light barrel.
Hence why the heavier barrel had less degradation in terms of group size despite the same firing schedule for both.
Hopefully we can also agree that rigidity has little impact on an AR's cold bore group sizes. The guy in the video (who everyone here seems to agree with) pretty much said as much with his comments regarding the Mk12. Even if you want to say the gov profile had an unfair advantage being button rifled, the Mk12 barrel has a doubly unfair advantage given that it's a precision rifled barrel that's also extremely rigid.
I think what we can say pretty definitely is that rigidity doesn't have much if any measurable effect on ARs, but thermal mass does.
Hence why the heavier barrel had less degradation in terms of group size despite the same firing schedule for both.
You must have been watching a different video to be able to tell that one barrel's group is bigger or smaller than the others.
First, with 36 total rounds through two different rifles, that is not a good statistical sample.
Second, with two different barrel made by two different manufacturers to two different quality standards, you really cannot draw any comparative conclusions between the barrels.
Third, the only thing to can really compare is the performance of each barrel cold to its performance hot.
So, the only thing you can deduce from the four groups is that both opened up as the barrel heated up, and the POI shifted, that's all.
vicious_cb
01-09-23, 02:20
You must have been watching a different video to be able to tell that one barrel's group is bigger or smaller than the others.
First, with 36 total rounds through two different rifles, that is not a good statistical sample.
Second, with two different barrel made by two different manufacturers to two different quality standards, you really cannot draw any comparative conclusions between the barrels.
Third, the only thing to can really compare is the performance of each barrel cold to its performance hot.
So, the only thing you can deduce from the four groups is that both opened up as the barrel heated up, and the POI shifted, that's all.
In case you didnt notice to you are trying to argue logic with a person that can't tell the difference between reality and his own delusions. You may have also noticed from the other comments in the thread this isnt the first time he's done this.
Im guessing this guy tends to get off his meds every few months and starts posting on topics his delusional mind thinks he understands.
In case you didnt notice to you are trying to argue logic with a person that can't tell the difference between reality and his own delusions. You may have also noticed from the other comments in the thread this isnt the first time he's done this.
Im guessing this guy tends to get off his meds every few months and starts posting on topics his delusional mind thinks he understands.
While I am replying to him, he is not my intended audence.
My intended audience is all the other people that may, or may not, know any more about engineering but read this thread. Yes, I am pretty sure that this guy isn't going to learn anything, because he is not open to learning. Others that read this thread might be less myopic, and leave a little smarter.
While I am replying to him, he is not my intended audence.
My intended audience is all the other people that may, or may not, know any more about engineering but read this thread. Yes, I am pretty sure that this guy isn't going to learn anything, because he is not open to learning. Others that read this thread might be less myopic, and leave a little smarter.
I know I'm getting a lot out of reading what you're writing. Thank you.
I know I'm getting a lot out of reading what you're writing. Thank you.
Seconded.
titsonritz
01-11-23, 13:40
I know I'm getting a lot out of reading what you're writing. Thank you.
Likewise for sure.
Likewise for sure.
What they said
You must have been watching a different video to be able to tell that one barrel's group is bigger or smaller than the others.
First, with 36 total rounds through two different rifles, that is not a good statistical sample.
Second, with two different barrel made by two different manufacturers to two different quality standards, you really cannot draw any comparative conclusions between the barrels.
Third, the only thing to can really compare is the performance of each barrel cold to its performance hot.
So, the only thing you can deduce from the four groups is that both opened up as the barrel heated up, and the POI shifted, that's all.
Well I agree the sample size isn't big enough to really make any determination, but I'm also not the one who posted it as evidence of anything. All I'm saying is if we're going to draw any conclusions from that video then the only conclusions that could be drawn support my opinion from the outset, which is that 1) barrel stiffness has very little influence on an AR's accuracy and 2) that thermal mass and surface area are much more important to holding tighter groups.
vicious_cb
01-15-23, 00:45
Well I agree the sample size isn't big enough to really make any determination, but I'm also not the one who posted it as evidence of anything. All I'm saying is if we're going to draw any conclusions from that video then the only conclusions that could be drawn support my opinion from the outset, which is that 1) barrel stiffness has very little influence on an AR's accuracy and 2) that thermal mass and surface area are much more important to holding tighter groups.
Not sure how you can still come up with the opposite conclusion that everyone else saw from the video including the video's own creators.
Are you retarded or something? Delusional? Both?
I just want it to be known that Okie and Cokie are two different people that have never met. I am an idiot in my own special way, to be clear, but I wanted to throw my two cents in.
I’ve shot bolt guns for a long time, and IME, lighter barrels vs heavy barrel perform very similar to Molon’s data on the 14.5” barrels that differ in profile from heavy to skinny. It’s around here somewhere, and the heavy barrels were more accurate, skinny barrels slightly less accurate. That’s all the data I have to draw from. Everything else I have to add is anecdotal.
I do not understand material science. However, I’ve seen in the past that fluted barrel did lose accuracy faster than straight Palma/M24 profile barrels. Basing these experiences off molon’s results would lead me to believe removing material in any way, whether uniformly across an entire barrel, or in flutes or dimples affects accuracy in similar but not necessarily equal ways. Fluted barrels may be better than skinnier barrels of equal weights, but I have neither data nor anecdote to support that.
Carbon fiber barrels are cool looking and niche. It was cool to see the proof guy bash a cinder block with one. I personally think they are best used in hunting applications or other low volume shooting applications where lightweight guns are needed. Steel beats it in any other way. Fluting cannot make a barrel stronger though. Wtf.
This could probably be a standalone thread, but I’m curious if a ball end mill dimpled barrel is stiffer/more rigid than a straight flute barrel of the same mass?
This could probably be a standalone thread, but I’m curious if a ball end mill dimpled barrel is stiffer/more rigid than a straight flute barrel of the same mass?
For the same weight, length and caliber, the stiffer barrel will have the material situated as far as possible from the axis of symmetry (large radius). That's why longitudinal flutes are very good at adding stiffness.
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