View Full Version : Why do folks like the M4 barrel profile?
mkmckinley
10-07-09, 12:42
It seems like most of the uppers available with 14" and 16" barrels have the "m4 profile" with the m203 notch. It must be market driven but why is this seen as desirable? It's not even close to an optimal contour unless you have a 203. Not many do. I'm surprised that the 203 notch isn't a rare specialty thing. Is there something I'm missing?
Weight savings. Yeah, that's it, weight savings. :D
I think it's something the market initially adopted to sell rifles to the civilian market that "look" like the same rifles that the Military uses. Otherwise, I dont see a practical use for the M4 profile barrel.
Its good to see some of the forward thinking companies (BCM, Daniel Defense, etc.) making rifles with more practical mid-length and lightweight profile barrels for the civilian & LE market.
Gutshot John
10-07-09, 13:48
I don't have an actual answer but if I had to guess I'd say it's simpler for manufacturing purposes.
One less machine to buy since you have to make the 203 notch anyway.
It's not "desirable" except that it's cheaper than producing a whole separate barrel profile.
for some reason i always had it in my head that it was a thinner "pencil" barrel. not just a notch.
just found this in a search
http://www.ar15barrels.com/profiles.shtml
Nice link, glockeyed, very informative. Thanks!
It seems like most of the uppers available with 14" and 16" barrels have the "m4 profile" with the m203 notch. It must be market driven but why is this seen as desirable? It's not even close to an optimal contour unless you have a 203. Not many do. I'm surprised that the 203 notch isn't a rare specialty thing. Is there something I'm missing?
I really have no idea, but I do know that the interest in that profile is dying down.
The consumer is becoming more educated and are wanting either Govt profile or pencil barrel designs.
C4
sonrider657
10-07-09, 16:08
Why is demand for Government Profile increasing? It seems to be completely backward.
Why is demand for Government Profile increasing? It seems to be completely backward.
Govt profile is about the same weight without that goofy step in it (which does not help accuracy in ANY way).
C4
Beat Trash
10-07-09, 16:27
My answer to the original question is because it came on my first 6920 I purchased.
I have had a Colt 6520 since around 1994 or 95. Great gun that has a pencil barrel. I love the thing. But as my eyes matured, and Red Dot optics improved, my desire for a flat top gun got the best of me.
While I still own that 6520, I have obtained a few 6920's over years the since the end of the AWB. If they had the option of a flat topped 6520, with a pencil barrel vs. a M4 cut barrel, I would have probably went that route.
Truth be told, since all of the training I have done the last few years, both on my one time, and at work, has been with either my 6920's, or the Department's Bushmasters & M&P's (all 16" M4 type barrels), I have gotten used to the feel and balance of this type of barrel.
I don't necessarily like the M4 profile, but I have gotten used to it.
Train with the guns and equipment you have, not with what you wish you had. Seems to work for me so far...
It's gottahaveit syndrome. If the .Mil suddenly changed to a slanted 8-port flash hider with chrome lining and a bell hanging off of it, manufacturers couldn't make/sell them fast enough.
Gun makers market heavily towards the LE/Mil market even though its a small part of their sales simply because they know the public will want to have whatever the troops are using.
I have an M4 profile barrel, but it isn't because of any particular fascination with it. It just happened to be what LMT uses, and it looks "normal" to me on a 14.5" barrel. I hate seeing 16" barrels with it though. They just look wrong.
Jay
It's gottahaveit syndrome.
For some folks maybe. There's not a huge selection in 14.5" barrel profiles that differ from the standard M4.
I'm more concerned with the make of the barrel than the profile. I don't find the M4 profile to be heavy at all. It balances better than my SBRs for whatever reason.
For me the gun I wanted had that type of barrel. Other than that I don't care about the cutout.
I hate the look of the 16" M4 barrel, but kinda like the look of the 14.5" and under with the notch.
The 16" barrel balances fine, but just looks wrong. :D
mkmckinley
10-07-09, 17:15
It was my understanding that the original A1 barrel profile was sort of like the lightweight or "pencil" type profile. They were bending under field conditions so the Army beefed it up distal to the handguards. They shortened it for the M4 then the 203 came out and the notch happened. That's how we got the frankenbarrels on our M4's. Someone with more experience can probably correct me if I'm wrong.
Now some of the USGI m4's are HBAR profile under the handguards and normal government after. There are two vertical flat notches near the breach to, again, accommodate the 203. I'd love to know how the barrel harmonics play out in that bad boy especially with all the crap we put on our rails. Also, you wouldn't believe how front heavy they are. I picked up an old M16A2 and it felt downright handy.
Anyway I just think it's funny that the M4 profile is so popular given that almost nobody has a 203 or is performing bayonette drills. There's probably nothing wrong with it on a combat carbine, but I like that Noveske profile a little better.
Beat Trash
10-07-09, 18:05
It was my understanding that the original A1 barrel profile was sort of like the lightweight or "pencil" type profile.
The first three of the four years I spent in the Marine Corps were with M16A1's. My first AR15 after getting out was a Colt SP1 (Think M16A1 w/o the full auto and forward assist.) Both had what would now be called pencil barrels.
We were told the reason for going to a larger diameter barrel on the M16A2 was because barrels were being bent behind the front sight base by individuals using their M16A1's with bayonet attached to pry open packing crates. Of course we were told this only happened in the Army, as a Marine would never do something as stupid with their rifle...
I do not know if this is true, but yes, I could easily see this being an issue...
The_War_Wagon
10-07-09, 19:26
The high CDI factor. ;)
I wish it wasn't so popular. The Noveske barrel profile, or simply no 203 notch, or a lightweight, all of those are better.
RogerinTPA
10-07-09, 19:49
It seems like most of the uppers available with 14" and 16" barrels have the "m4 profile" with the m203 notch. It must be market driven but why is this seen as desirable? It's not even close to an optimal contour unless you have a 203. Not many do. I'm surprised that the 203 notch isn't a rare specialty thing. Is there something I'm missing?
Posers/Wannabees/CDI Factor/Marketing/Weight Savings.
I have 2 6920s, a Sabre Defense middy w/o the notch and a LMT MRP rifle rail w/o the notch, so I'm indifferent. I prefer the mid-length 16" barrel without the 203 notch, with a rifle rail for comfort and greater stability, but shoot all equally well. Now a pencil barrel with KAC rifle length URX would be the shizzle! :)
What is sad, my LWRC 16" upper does not have one and it almost seems wrong. We are so used to the M4 profile it seems the norm.
Govt profile is about the same weight without that goofy step in it (which does not help accuracy in ANY way).
C4
Grant,
Is the excessive machining (goofy step) the cause of accuracy detioration of the m4 profile??
I know the extreme short range accuracy guys used to detest any turning of the exterrior bbl blanks as it could cause warping or memory issues...as I remember it.
Thomas M-4
10-07-09, 20:10
The first three of the four years I spent in the Marine Corps were with M16A1's. My first AR15 after getting out was a Colt SP1 (Think M16A1 w/o the full auto and forward assist.) Both had what would now be called pencil barrels.
We were told the reason for going to a larger diameter barrel on the M16A2 was because barrels were being bent behind the front sight base by individuals using their M16A1's with bayonet attached to pry open packing crates. Of course we were told this only happened in the Army, as a Marine would never do something as stupid with their rifle...
I do not know if this is true, but yes, I could easily see this being an issue...
Hmm funny I was told in the Army we swapped over to the A2 because the Marines kept complaining they didn't have the M-14 Thats why the A2 got target sights, extra long butt stock and a heavier barrel so the Marine Corp could shoot there bulls eye paper targets.:D:p;)
RogerinTPA
10-07-09, 20:23
Hmm funny I was told in the Army we swapped over to the A2 because the Marine's kept complaining they didn't have the M-14 Thats why the A2 got target sights, extra long butt stock and a heavier barrel so the Marine Corp cold shoot there bulls eye paper targets.:D:p;)
That's what we were told in the 82d when we swapped out our A1s for A2s. To be compatible with the other ground forces (Marines) and they were too concerned about better ergros and better accuracy for punching paper for rifle matches.
M4 barrel profiles are probably cut by CNC program on a lathe - I doubt a separate machine would be necessary for each profile. I could be wrong.
What I have seen posted around the i-net by some is the assertion that an M4 profile is milspec and therefore intrinsically superior because of it. Therefore it's the only possible choice for a genuine M4gery. Ah huh.
Personally, the Gov't forcing the barrel to conform to the M203 mount rather than vice versa is a prime example of the way some decisions can be made in hierarchal bureaucracies. Was it really cheaper to make every barrel with a narrow section rather than fix the mounts? I guess.
Perhaps someone in on the groupthink or pulse on the line item expeditures might chime in.
Grant,
Is the excessive machining (goofy step) the cause of accuracy detioration of the m4 profile??
I know the extreme short range accuracy guys used to detest any turning of the exterrior bbl blanks as it could cause warping or memory issues...as I remember it.
Theoretically it can be, as it creates a (theoretical) weak point for the barrel to flex around as it heats up. One of my .pdfs has the "shoot 'til destruction" tests for the M4 and M16, wherein it described where the barrels would first fail. Gonna have to check it to see if the M4's barrel fails nearer that little notch (curiosity on my part).
I have no special fascination with the M4 profile, and would frankly rather not have it at all. Reading Lilja's articles about barrels has done quite a bit to influence what I want in a barrel (a consistent contour that promotes overall stiffness, for example, rather than the multiple steps or tiers of the M4 profiles).
-B
My SP1 Colt CAR back in the 80s had the light barrel, which I liked. Rather foolishly I got rid of it. The highly inferior (?) BM I now just came with the M4 profile. I don't dislike it intensely but neither do I need the weight. Comes the day I will replace it with a light "pencil barrel".
I actually don't think most buyers really care, from the safe-stuffer and internet-picture-poster to the "hard-use" guys, I don't really see much preference across the board. Yes, you have the replica builders that care, but beyond that there's little concern for the barrel profile.
I do think that there is a perception in the industry that buyers want a visually identical gun to what they see on CNN, I just don't think that "want" is really as strong as many think.
One could easily look at picture threads here and on TOS and make the assumption that everyone "wants" that profile, but it's much more common that people buy what they find available.
Manufacturers are coming around. BCM's midlength uppers are "government" profile with a thin .625" barrel under the handguards and a fatter .750 outside. Paul has posted that they will be putting out barrels that keep that .625"+/- all the way out. Take a look at Grant's thread on Colt 6520 barrels and you'll see a lot of people with interest in them. CMMG's "pencil" barrels were very popular as well.
To be sure, there are people that don't care either way. They don't mind the extra weight, or maybe even prefer it, but as Grant posted consumers are becoming more educated and are looking for things like the Noveske N4 barrel (which maintains the same overall weight but in a more sensible profile) and the 6520 or other .625" diameter barrel that is a more sensible profile AND lighter.
So yeah, I'm sure that somewhere out there you can find people that bought the M4 profile on purpose just because that's what they saw on CNN (or even what they were issued), but I truly don't think that most people really care. And if they did care at the initial purchase, it only takes 3 hours of a basic drills night to totally change their mindset.
Personally, the Gov't forcing the barrel to conform to the M203 mount rather than vice versa is a prime example of the way some decisions can be made in hierarchal bureaucracies. Was it really cheaper to make every barrel with a narrow section rather than fix the mounts? I guess.
Since the M203 is used on both the full sized rifle and the M4, they would have to stock two different sized mounts if the M4 barrel wasn't stepped (the full sized rifle is smaller under the handguards where the M203 clamps on).
rrpederson
10-08-09, 13:24
i dont actually know the answer to this question, but if i had to venture a guess, the notch almost makes the barrel appear shorter, i think because the lines/profile of the barrel are broken up by the notch. for me, its just my eyes playing tricks because i know that a 14.5" barrel is a 14.5" barrel. the notch serves only one purpose, and is useless otherwise. i think that its probably that and the "cool" factor.
Belmont31R
10-08-09, 13:42
Not a whole lot of companies make a 14.5" carbine barrel that is of quality.
Noveske makes one...
LMT, Colt, BCM do not.
I have two, and one is a Colt and the 2nd a LMT.
Also people tend to buy military 'type' guns like this, and stick with what they use.
Personally, the Gov't forcing the barrel to conform to the M203 mount rather than vice versa is a prime example of the way some decisions can be made in hierarchal bureaucracies. Was it really cheaper to make every barrel with a narrow section rather than fix the mounts? I guess.
Try mounting an M203 on a lightweight or heavy 12.5" plus carbine barrel. It would need a totally rigged mount to work. The notch is not only there because the mount is a small diameter, but also because it keeps the M203 from shifting forward.
Dustin
I don't have an actual answer but if I had to guess I'd say it's simpler for manufacturing purposes.
One less machine to buy since you have to make the 203 notch anyway.
It's not "desirable" except that it's cheaper than producing a whole separate barrel profile.
That would be my guess. It probably carried over into the private sector from companies such as Colt that had a govn't contract, therefore it was the most mil spec of all rifles before there were companies like LMT, BCM, Noveske etc. therefore a rifle with an M4 barrel profile is the most mil spec probably spread around the errornet like wildwire on places like TOS
The 14.5" M4 barrel is the only barrel in the 14.5" length that is readily available.
Until a company comes out with a quality LW 14.5", it will remain that way.
For a long time, it was the only readily available profile other than the stupid H-Bar and 11.5/5.5" flash hider barrels.
For a long time, it was the only readily available profile other than the stupid H-Bar and 11.5/5.5" flash hider barrels.
Very true.
I don't prefer it at all. I no longer sling a 203 so have no need for the cut; I have no practical use for it just like 99.99% of all other M4 users.
Failure2Stop
10-11-09, 07:23
The only reason I bought one is because it was the only readily available quality 14.5" barrel/upper without gettig into the Noveske price range.
If I had my choice at work I would carry something with a 16" middie Noveske Recon barrel.
That's what we were told in the 82d when we swapped out our A1s for A2s. To be compatible with the other ground forces (Marines) and they were too concerned about better ergros and better accuracy for punching paper for rifle matches.
I was in the 325AIR when we switched.
Over at LF, if you search around, there is a link to a document published in 83(?), it was written by an Officer somewhere in DA. It listed and described why the Army did not want the A2, and what it wanted instead.
Bottom line, the A2 supported USMC doctrine, not Army doctrine. Of the things the Army wanted were:
Shorter or adjustable stock
Night sights
Flat Top/Optics
Free float barrel
Ambi controls
1/9 twist
Good read, wish I had read that when I was a Pvt.
As far a the M4 contour, I'd prefer the LtWht barrel, but the 6920 comes with the M4, and its not that big of a deal.
I think Rob makes a good point, most of the "shooters" I know, that are really owners, just buy whats at the gun store or show, convince themselves, its just as good as, or is the greatest thing since canned bear, put it in the closet, and go play Golf.
Real shooters, like hear, know the differences, shop for and procure what we want. Or we make some concessions and compromises based on availability, prices, etc. and what we can and can't change easily. We do this fully aware of it, and not in some delusional haze.
Bob
School Circle, boots! Here's THE WORD!
Back in 1975, when I was at USMC Officer Candidate School, we were issued M14s, and taught how to use the flash suppressor and front sight to break the wire binding C-Ration cases by combat vets.
For whatever reason, when the Marines developed the -A2, they insisted on a thicker fore-barrel, while retaining the pencil profile under the handguards (the part, BTW, that bends under sling tension). This, presumably, was to accommodate the mounting for the M203, which was spec'ed for the M16A1 barrel profile.
As an aside, here's an Army document giving their opinion of the USMC M16A2 changes:
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA168577&Location=U2&doc=GetTRDoc.pdf
A very interesting read.
Yep thats the document, had my dates wrong, but.. I just re read.
When you read it, you need to keep in mind the time frame.
The document, mentions bayonet training as the reason the USMC wanted the thicker barrel.
Bob
Failure2Stop
10-11-09, 14:39
I find the whole thing somewhat humorous, if it wasn't for the fact that lives are the cost.
The Army blames the Marines for the A2.
The Marines blame the Shooting Teams for the A2 sights and stock and the Army for 3-round burst (and the resulting 3 different triggers).
The Shooting Teams blame the Air Force for the M16 in it's entirety.
I think that it's a travesty for so many to be stuck with the A4 (or *the horror* an A2), or M4s with M855. As it is now, the 203 notch on the M4 is irrelevant with the ability to mount the grenade launcher directly to rails.
Sadly (or not, depending on perspective), it will probably be easier to get a new system than to fix the M4 barrel. Then again, all but the slimmest percentage of M4-type shooters will be effected by the presence or lack of the 203 notch.
For a long time, it was the only readily available profile other than the stupid H-Bar and 11.5/5.5" flash hider barrels.
Why is it stupid? I have one and like it!
Hey now! In the document, it clearly states the Army did not want the 3 round burst:D
FWIW, I'm sure we all would be surprised by how much out there, gun related or not, was designed around some odd, but important at the time, parameter, that escapes us now.
I'm sure, when the M4 was developed, the simplest means of putting an M203 on the gun was with the step cut. No one probably even thought of another means, or felt that the older system would suffice, until a newer one replaced it.
Just recently, I read one of those trivia type emails, or what not, that traced the size of some part on the space shuttle, the rocket engine, I think, to the wheel base of a Roman Chariot! True or not, I don't know, but its not entirely out of the realm of possibility.
Bob
Failure2Stop
10-11-09, 15:52
At the risk of going off topic for a second-
Hey now! In the document, it clearly states the Army did not want the 3 round burst:D
Hey now, I didn't say the Army wanted it, just that the Marines blame them for it. Guilt or innocence has no bearing on the placing of blame :p.
I just read the .pdf linked by shep854 and all I can say is that it makes so much sense it is no wonder that everyone ignored it. Seriously. It pretty much called everyone out on the carpet and exposed their silliness. Rushing to buy unproven but promising items seem to be a hall-mark of the USMC acquisitions machine- from the A2 to MOLLE to the MTV, issues and band-aids keep popping up.
(Don't get me wrong, the Army has made all kinds of silly errors as well.)
I have some anecdotal data that indicates that the USMC was not as happy with the A2 as it would seem, but that whoever was in charge of the PIP simply removed the last page of the requested changes (which supposedly included the return to auto and shorter stock) and submitted it to stay under budget. While the information is anecdotal, it does come from a high source.
Now, back to topic before I have to give myself a warning-
I think that you are correct, Bob, with regard to 203 fastening to the barrel. It's frightening to think of the legacy interface and band-aid issues we are still dealing with when it comes to the platform. The problem seems to be that most people focus on the wrong problems instead of the critical ones and seek material solutions for training issues.
I don't think its really off topic as much as it is an offshoot of it.
Why do some shooters like the M4 barrel? Leads to why the M4 barrel exists in the first place, which brings us to the institutional reasoning behind some systems component, out dated as they maybe.
Also consider how many older systems are still around. So even with a better way to attach an M203, we still have A2's and new M4's in the system, so now we are at two different attaching systems, then when a new GL comes on line,.... and well you can see where this goes.
To be fair also, the document recognized training shortfalls in the Army, but also realizes the challenges, what is now called the Big Army, has in training such large numbers of Soldiers.
Notice how much of what they recommended in 1986(?) Has come to fruition in the M4?
Bob
ETA, notice a parallel with the uniform?
As it is now, the 203 notch on the M4 is irrelevant with the ability to mount the grenade launcher directly to rails.
I don't see why you find this to be beneficial as a rail mounted M203 hangs lower and makes the whole rifle/launcher combo more bulky than a barrel mounted M203 setup.
Failure2Stop
10-11-09, 17:52
I don't see why you find this to be beneficial as a rail mounted M203 hangs lower and makes the whole rifle/launcher combo more bulky than a barrel mounted M203 setup.
It is a little more bulky, but at least I can pop it on and off easily.
I hate the 203. Even in the "slim" mounting method it is bulky and robs the shooter of the ability to really get busy with the rifle/carbine. I can go on and on about the damn thing, but to cut to the chase; a grenade launcher would be more effective as a stand-alone weapon stuck in a weapon catch (like a breaching shotty) for the infrequent times that inefficent HEDP is the answer or for illumination/marking (which are better performed by other solutions).
RogerinTPA
10-11-09, 18:11
School Circle, boots! Here's THE WORD!
Back in 1975, when I was at USMC Officer Candidate School, we were issued M14s, and taught how to use the flash suppressor and front sight to break the wire binding C-Ration cases by combat vets.
For whatever reason, when the Marines developed the -A2, they insisted on a thicker fore-barrel, while retaining the pencil profile under the handguards (the part, BTW, that bends under sling tension). This, presumably, was to accommodate the mounting for the M203, which was spec'ed for the M16A1 barrel profile.
As an aside, here's an Army document giving their opinion of the USMC M16A2 changes:
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA168577&Location=U2&doc=GetTRDoc.pdf
A very interesting read.
Alas! My eyes can see!
Very interesting read indeed. In as much as all of the Army recommendations and training requirements, were completely ignored. Amazing. Thanks for the post shep.
Plus how many AR owners are going to attach a grenade luncher to there rifle? I would say not many! Just a waste of money to make that cut in the outside of barrel for the M4 look.
Is that a 325 crest I see there?
Bob
Yes sir it is. I was in the 3/325th Abn Inf-82nd Abn Div. :D
Interesting find on page 31, and I will quote "a 1:9 twist appears to be optimum for the army rifle". Let the arguing commence.
wild_wild_wes
10-11-09, 23:46
While the completion backwards principle M-4 barrel profile is indeed strange, so too is the Marine Corps adoption of the M-16A4 rifle with 20" barrel and fixed buttstock. What was the rationale behind that retrograde move?
Yes sir it is. I was in the 3/325th Abn Inf-82nd Abn Div. :D
1/325AIR '87-'94, with a year as BlackHAt at Advanced Airborne
Bob
Interesting find on page 31, and I will quote "a 1:9 twist appears to be optimum for the army rifle". Let the arguing commence.
Like I said, remember the time frame. Early 80's was when the testing and reporting was done, with '86(?) being when the report was published. were teh 70grn plus .224 bullets even available. or thought of?
Bob
1/325AIR '87-'94, with a year as BlackHAt at Advanced Airborne
Bob
Nice! Was in from Oct-82'-Feb-85'.
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