View Full Version : Loctite
rcoodyar15
08-09-15, 18:12
Any here ever tried gluing their barrel extension into the receiver with Loctite?
Why would someone want to do that?
I will use locktite on the barrel extension on a target/long range rifle. I will not do it with a standard rifle. I like to take my hard use rifles apart once in a while to clean them up thoroughly so I won't use locktite. If you get a quality receiver that you have to heat up to get the barrel in then locktite may not be necessary.
I do it on precision builds
sevenhelmet
08-09-15, 19:16
Ummmm, no. A properly fitted and lapped barrel extension fit in the receiver would be more important for accuracy than "gluing" them together. The loctite will most likely break down under the heat of firing anyway, so why bother?
I will use locktite on the barrel extension on a target/long range rifle. I will not do it with a standard rifle. I like to take my hard use rifles apart once in a while to clean them up thoroughly so I won't use locktite. If you get a quality receiver that you have to heat up to get the barrel in then locktite may not be necessary.
I do it on precision builds
Any reason why? What color? If everything is in spec, and the BN is properly torqued, why is loctite needed for anything other than filling in the gaps between the upper and extension?
Any reason why? What color? If everything is in spec, and the BN is properly torqued, why is loctite needed for anything other than filling in the gaps between the upper and extension?
You're essentially bedding the barrel to the receiver. Here is a good thread on the topic - https://www.m4carbine.net/showthread.php?119904-Applying-loctite-to-increase-accuracy
You're essentially bedding the barrel to the receiver. Here is a good thread on the topic - https://www.m4carbine.net/showthread.php?119904-Applying-loctite-to-increase-accuracy
I just read through that thread, and it didn't exactly illuminate anything in regards to the efficacy of using loctite.
Ummmm, no. A properly fitted and lapped barrel extension fit in the receiver would be more important for accuracy than "gluing" them together. The loctite will most likely break down under the heat of firing anyway, so why bother?
I tend to agree with this notion.....but I guess the phrase "how can it hurt" comes into play here. Other than difficulty removing your barrel from your upper, what are the drawbacks?
One note on this, after removing my White Oak barrel from a WOA factory upper, I noticed that they used red loctite and it was a PIA to remove. I'm rebuilding my precision upper using a billet upper, but I'm not going to use loctite (only anti-sieze grease) when assembling everything back together.
sevenhelmet
08-09-15, 20:36
Drawback I can think of is precisely what you stated: not being able to separate the barrel from the upper if/when it is desired to do so. Deep cleaning? Barrel replacement?
Not to mention the unknowns of having a chemical inside your upper which isn't designed for the heat loads its experiencing there.
What makes you think you wouldn't be able to take them apart?
Applying a heat gun to the parts will make them easily removable. There is no permanent loctite.
That being said, red loctite isn't what I would use, but rather the sleeve retaining versions which are typically green. I think its 607. Its not going to make a 3 MOA gun a 1/2 MOA one. But, you might make your 3/4 MOA rifle more consistent across different tempratures or take that 3/4 MOA and maybe make it a 5/8 MOA.
If its not a rifle I'm going to shoot for groups, I wouldn't bother.
What makes you think you wouldn't be able to take them apart?
Applying a heat gun to the parts will make them easily removable. There is no permanent loctite.
That being said, red loctite isn't what I would use, but rather the sleeve retaining versions which are typically green. I think its 607. Its not going to make a 3 MOA gun a 1/2 MOA one. But, you might make your 3/4 MOA rifle more consistent across different tempratures or take that 3/4 MOA and maybe make it a 5/8 MOA.
If its not a rifle I'm going to shoot for groups, I wouldn't bother.
So just for clarification, you are stating that using loctite will help improve accuracy from 3/4 MOA to 5/8? And this is based on what exactly?
rcoodyar15
08-09-15, 21:31
So just for clarification, you are stating that using loctite will help improve accuracy from 3/4 MOA to 5/8? And this is based on what exactly?
really I have been reading a lot about it. Looks like a lot of the precision upper builders are doing it.
Well since I am third in the MOA thread and I did it to my gun today we will see if it can take a 3/4 MOA gun and make it better. Same ammo next weekend with a glued barrel.
Looks like a good experiment.
really I have been reading a lot about it. Looks like a lot of the precision upper builders are doing it.
Well since I am third in the MOA thread and I did it to my gun today we will see if it can take a 3/4 MOA gun and make it better. Same ammo next weekend with a glued barrel.
Looks like a good experiment.
Same here when I get my 20" WOA put back together.......I just need to find an upper!
So just for clarification, you are stating that using loctite will help improve accuracy from 3/4 MOA to 5/8? And this is based on what exactly?
I would first direct you to my use of the word maybe...which wasn't an accident.
I have noticed that in the last two uppers I've put together when I bedded things that they were more consistent. Not necessarily more accurate, but across all recorded groups there was less deviation. A dropping of "flyers" as it were.
I think that using a quality, tight-fitting upper receiver, such as the BCM4, would do more good than using Loctite.
I think that using a quality, tight-fitting upper receiver, such as the BCM4, would do more good than using Loctite.
Don't get me wrong. I completely agree that a tight fitting upper is the most ideal solution. Not wanting to completely jerk BCM off, they only have a say in half of the equation. The barrel extension also has an effect here. So unless you are in a position to test fit many different parts to find the most ideal fit, bedding is just a tool to have in your back pocket should you find that your purchased parts aren't quite ideal.
What makes you think you wouldn't be able to take them apart?
Applying a heat gun to the parts will make them easily removable. There is no permanent loctite.
That being said, red loctite isn't what I would use, but rather the sleeve retaining versions which are typically green. I think its 607. Its not going to make a 3 MOA gun a 1/2 MOA one. But, you might make your 3/4 MOA rifle more consistent across different tempratures or take that 3/4 MOA and maybe make it a 5/8 MOA.
If its not a rifle I'm going to shoot for groups, I wouldn't bother.
Permatex 640 is good to 400F - Mil-R-46082B Type II - static sheer at 300F - 1500psi
Loctite 609 is good to 300F - Mil-R-46082B Type I - static sheer at 300F - 1000psi
Both met Mil-R-46082B which requires -65 to 300F temp range.
The normal clearance filling ability of the retaining compounds is as follows: Type I -.004 inch, (,0.102mm) Type II -.008 inch (0.203mm). For optimum strength and cure, the clearance should not exceed .002 inch (0.058mm). (From the Mil-Spec)
Permatex 640 is good to 400F - Mil-R-46082B Type II - static sheer at 300F - 1500psi
Loctite 609 is good to 300F - Mil-R-46082B Type I - static sheer at 300F - 1000psi
Both met Mil-R-46082B which requires -65 to 300F temp range.
The normal clearance filling ability of the retaining compounds is as follows: Type I -.004 inch, (,0.102mm) Type II -.008 inch (0.203mm). For optimum strength and cure, the clearance should not exceed .002 inch (0.058mm). (From the Mil-Spec)
Diameter of the hole in the upper: 1.000" +.002"
Diameter of barrel extension: .9987" -.0008"
Clearance: between .0013" and .0041"
Should be good enough to hold fairly well.....especially since you really don't care if you get maximum strength.
Diameter of the hole in the upper: 1.000" +.002"
Diameter of barrel extension: .9987" -.0008"
Clearance: between .0013" and .0041"
Should be good enough to hold fairly well.....especially since you really don't care if you get maximum strength.
Thanks for that info - I think I'll give it a try.
rcoodyar15
08-10-15, 11:17
yep
I Disassembled my upper. degreased the barrel extension and inside of the receiver with brake cleaner. put a nice coat of red 271 Loctite on the receiver extension. Slid her home and cleaned up my overruns. screwed on the barrel nut to 35# of torque. took the assembly off the reaction rod and with qtips cleaned up the excess on the inside of the receiver/barrel extension. got it standing in a corner with the receiver up. Will let it dry till Friday.
last weekend I shot the MOA challenge before gluing in the barrel. That is pretty much what this gun averages. I am in third place. This Saturday I will use the same bullet and load and shoot the challenge again. We will see if there is any improvement.
Who believes there will be improvement? not?
This is AR Technical discussion. Blanket statements such as "loctite will burn off" or "just buy a BCM" are worthless and add nothing to the conversation.
Bill from Alexander Arms use(d?) Loctite 243. I find it interesting he decided to use a thread locker. Loctite 609 looks interesting, especially since its labeled as "Recommended for parts that will need subsequent dismantling, i.e., retention of bearings onto shafts and into housings." My guess is a retaining compound wasn't chosen as, obviously, we are using a barrel nut.
I read somewhere else people use similar compounds on the barrel between the gas block. If anyone has any insight on this i'd love to hear about it.
yep
I Disassembled my upper. degreased the barrel extension and inside of the receiver with brake cleaner. put a nice coat of red 271 Loctite on the receiver extension. Slid her home and cleaned up my overruns. screwed on the barrel nut to 35# of torque. took the assembly off the reaction rod and with qtips cleaned up the excess on the inside of the receiver/barrel extension. got it standing in a corner with the receiver up. Will let it dry till Friday.
last weekend I shot the MOA challenge before gluing in the barrel. That is pretty much what this gun averages. I am in third place. This Saturday I will use the same bullet and load and shoot the challenge again. We will see if there is any improvement.
Who believes there will be improvement? not?
I don't believe you will see any improvement you can measure or repeat. .The potential for improvement is small compared to a reasonable margin of error.
This is AR Technical discussion. Blanket statements such as "loctite will burn off" or "just buy a BCM" are worthless and add nothing to the conversation.
Technically speaking, using a receiver that has a tight barrel extension fit and has been checked to be square and true will produce more, positive results, than applying a substance to the barrel extension that does not belong there. The BCM4 was merely used as an example, because it is specifically designed for this purpose. Technically speaking, of course.
I use blue locktite.
My long range rifle has a Precision Firearms billet upper that I had to heat to get the barrel extension in. I put a very light coating of locktite on the barrel extension and inserted the barrel. I then used a drop on the threads because I only used about 40 ft/lbs of torque on the barrel nut.
This particular rifle will never get to 300 degrees when it is fired and I won't be tearing it down nearly as much as my hard use rifles.
rcoodyar15
08-10-15, 16:56
this is exactly the kind of input I am looking for.
Personally I am an experimenter and this gun is an experiment.
I know many on this forum are locked into the milspec mindset. Well I like to think outside the box. We are doing things with the AR's they were never designed for. how can milspec possibly work for that. I am looking for better than milspec.
I built this one to play with. I really don't care if it works or not but I want to know.
There isn't anything milspec about receivers milled for tight fit with barrel extension, checking receivers for squareness and trueness, hitting specific barrel nut torque values, shimming muzzle devices, squaring barrels to the bore line, fitted bolts, attention to the barrel crown. Along with hand loading ammunition, these are things that improve accuracy. I do not believe in using Loctite on a barrel extension, as a way to improve accuracy.
I use blue locktite.
My long range rifle has a Precision Firearms billet upper that I had to heat to get the barrel extension in. I put a very light coating of locktite on the barrel extension and inserted the barrel. I then used a drop on the threads because I only used about 40 ft/lbs of torque on the barrel nut.
This particular rifle will never get to 300 degrees when it is fired and I won't be tearing it down nearly as much as my hard use rifles.
If the extension is a sweat fit into the receiver what is the loc-tite doing other than making things harder to take apart?
There isn't anything milspec about receivers milled for tight fit with barrel extension, checking receivers for squareness and trueness, hitting specific barrel nut torque values, shimming muzzle devices, squaring barrels to the bore line, fitted bolts, attention to the barrel crown. Along with hand loading ammunition, these are things that improve accuracy. I do not believe in using Loctite on a barrel extension, as a way to improve accuracy.
I would like to hear just one person say.... I cannot prove it does anything but it makes me feel better to do it.
Loktite on a barrel extension may change the harmonics on the barrel when fired...(whether it be for better or worse from with no Loktite).
I guess we will see from your experiment.
Also there is the new gun syndrome(sometimes we shoot better if we think we did something to improve the rifle).
Multiple shots will tell.
I did not use any Loktite on my BCM4 and Lija AR24 barrel cause it was very tight(tight enough that I do not think Loktite would have made any difference when it cured/dried to form any bedding to speak of.
I did face the receiver .002" using the Brownells tool by hand cause I could put a .0015" feeler gauge from the 7-1 o'clock position and see daylight.
Just took enough off the receiver face to have zero clearance and torqued barrel nut to 45ft.lbs.
We will see in due time how she performs.
Again, good luck with your experiment and let us know the true results.
Clarence
I would like to hear just one person say.... I cannot prove it does anything but it makes me feel better to do it.
I cannot prove it does anything but it makes me feel better to do it ;)
I got one of the Larue barrels during the sale and I have an old LMT upper that is getting long in the tooth. The upper is in good shape and in spec. I always do my own builds except for precision builds (not that I am trying very hard with an old LMT upper) becuase my local smith, who is a friend, has always recommended lapping the receiver. He has the Brownells tool and he also asks (kind of recommends) adding locktite to the barrel extension.
Someone posted a video in a thread not to long ago, which I have been trying to find since this thread came up with no luck that outlines the theory of how the loctite somewhat kills the side to side motion of the barrel. If someone finds it please post it, it was in regards to national match builds.
Like lapping the receiver I don't see it hurting anything. It has been used by varmit hunters for a while now.
rcoodyar15
08-10-15, 19:24
There isn't anything milspec about receivers milled for tight fit with barrel extension, checking receivers for squareness and trueness, hitting specific barrel nut torque values, shimming muzzle devices, squaring barrels to the bore line, fitted bolts, attention to the barrel crown. Along with hand loading ammunition, these are things that improve accuracy. I do not believe in using Loctite on a barrel extension, as a way to improve accuracy.
Actually there are quite a few precision upper builders doing it. Do a little google search.
done all of that except for muzzle devices. don't use them on my precision barrels. You really don't have much control over how tight the fit between receiver and barrel extension will be. I have have used high priced billet uppers, Vltor mur, DPMS some are tighter than others.
I guess we will find out. I have tried a lot of things. Some work better than others.
If you want to see how the gun groups prior to gluing the barrel in I am number 3 in the MOA challenge in the Precision Rifle Simi Automatic on this forum. That is pretty representative of the average group for this rifle. Sure I have shot better but this is 5 5 shot groups. This Saturday I will shoot the same load and bullet again. We will see what the change is if any. I really have no expectations. I have tried so many different things. Some worked better than others.
Personally, I would not want to do something that would not be done at the factory...as far as lock tight on a barrel.
yep
I Disassembled my upper. degreased the barrel extension and inside of the receiver with brake cleaner. put a nice coat of red 271 Loctite on the receiver extension. Slid her home and cleaned up my overruns. screwed on the barrel nut to 35# of torque. took the assembly off the reaction rod and with qtips cleaned up the excess on the inside of the receiver/barrel extension. got it standing in a corner with the receiver up. Will let it dry till Friday.
last weekend I shot the MOA challenge before gluing in the barrel. That is pretty much what this gun averages. I am in third place. This Saturday I will use the same bullet and load and shoot the challenge again. We will see if there is any improvement.
Who believes there will be improvement? not?
Enjoy it while you can......my 20" WOA upper is almost finished......and I ordered a new scope!!!! ;)
I would like to hear just one person say.... I cannot prove it does anything but it makes me feel better to do it.
Posts like this are so refreshing in here.......conjecture seems to be a prerequisite in the Tech section.
Actually there are quite a few precision upper builders doing it. Do a little google search.
I do not believe in using Loctite on a barrel extension, as a way to improve accuracy.
done all of that except for muzzle devices. don't use them on my precision barrels. You really don't have much control over how tight the fit between receiver and barrel extension will be. I have have used high priced billet uppers, Vltor mur, DPMS some are tighter than others.
There are companies that will fulfill a customer's desire to get a tight fitting, square, and true upper receiver. They could probably make sure your barrel fit exactly how you want it to.
I guess we will find out. I have tried a lot of things. Some work better than others.
If you want to see how the gun groups prior to gluing the barrel in I am number 3 in the MOA challenge in the Precision Rifle Simi Automatic on this forum. That is pretty representative of the average group for this rifle. Sure I have shot better but this is 5 5 shot groups. This Saturday I will shoot the same load and bullet again. We will see what the change is if any. I really have no expectations. I have tried so many different things. Some worked better than others.
Unless you do some testing, like Molon, which would break the rules of that "competition", you will never know the potential of your rifle...only the potential of the rifle in your hands. An awful shooter can make a fine rifle look bad. That is not a dig at you, but in the name of scientific experimentation, you would need to remove as many variable as possible to verify exactly how much of a difference the Loctite made in regards to the accuracy of your rifle.
TXBK, did you read the thread I posted above?
TXBK, did you read the thread I posted above?
Yes sir, but I still don't believe in using Loctite as a way to improve accuracy. It seems to me that Loctite may be used by some to make up for the quality and specs, or lack there of, of the components being used. Seriously, what improvements are expected by using Loctite on the barrel extension of an AR-15? I understand that benchrest shooters can be a kooky bunch, with some of their methods, because I work with one.
Good information in here for sure, and I think at the end of the day, we have established that there is no empirical data to support either side of the discussion. One thing I read though however, is the notion of using loctite on upper receiver threads when installing a BN. I'm no armorer, but I've assembled enough AR's and read enough about the topic to know this is probably the worst advice anyone can give.
I use blue locktite.
My long range rifle has a Precision Firearms billet upper that I had to heat to get the barrel extension in. I put a very light coating of locktite on the barrel extension and inserted the barrel. I then used a drop on the threads because I only used about 40 ft/lbs of torque on the barrel nut.
This particular rifle will never get to 300 degrees when it is fired and I won't be tearing it down nearly as much as my hard use rifles.
Good information in here for sure, and I think at the end of the day, we have established that there is no empirical data to support either side of the discussion. One thing I read though however, is the notion of using loctite on upper receiver threads when installing a BN. I'm no armorer, but I've assembled enough AR's and read enough about the topic to know this is probably the worst advice anyone can give.
Don't tell anyone at KAC...
Don't tell anyone at KAC...
Well that settles it....BCM, Noveske, Adco, Rainier Arms don't according to my research. Besides making removal a PITA, what is the point exactly? In fact I read that Adco (one of the most respected armorers in the industry) has openly criticized using loctite. But I'm probably wrong, and soon there will be responses recommending cement or concrete on my weapon system to improve accuracy. :blink:
Technically speaking, using a receiver that has a tight barrel extension fit and has been checked to be square and true will produce more, positive results, than applying a substance to the barrel extension that does not belong there. The BCM4 was merely used as an example, because it is specifically designed for this purpose. Technically speaking, of course.
I don't think anyone is debating that quality components are more important than the assembly process.
This is a quote I found on the grendel forums and, supposedly, Bill Alexander states "It has been found that the harmonics of the Grendel can cause vertical stringing. So to lock this down without LockTite you are talking over 70foot-pounds of torque on the barrel nut. That can be hard on the receivers. As a solution that seems to work quite well was to bed the barrel and gas block in the LockTite 2440 (replaced with 243) and torque to normal specs."
http://www.65grendel.com/forum/showthread.php?1791-Building-for-accuracy
Take that for what it is worth, as I do not have the direct link to quote where he says this.
Also, i've found that JP rifles recommends coating the barrel with Loctite 609 when installing their adjustable gas block.
The 6.5 Grendel is a different animal than the 5.56 AR's I thought we were talking about. I think JP does more than a few kooky things with AR15's. If using some form of Loctite on every possible thread makes someone feel warm and fuzzy, they should rock on warm and fuzzily. It is still such an unnecessary and ill-advised way to install an AR15 barrel.
I know JP Rifles does a thermal fit of their barrels (with barrel extension) into their upper receivers. They heat one part and/or cool another. The exact process is a trade secret. But the end result is the fit is VERY tight. I believe they have even fired guns in private testing without the barrel nuts attached.
JP Rifles are known in the competition world for their super accurate ARs.
I've never Loctited a barrel extension into an upper receiver. But I would bet money that it does not hurt accuracy, and probably helps. I just don't think there is very much to gain, and would rather have a gun that can be detailed stripped/disassembled with no issues.
Joe Mamma
The 6.5 and the 5.56 are based upon the same platform, and I would ASSume the same principals would apply. Naturally i'm talking out of my ass a little because i'm largely unfamiliar with the 6.5.
The 6.5 is an in between cartridge. Pretty much halfway between 7.62x51 and 5.56x45.
rcoodyar15
08-11-15, 05:01
Enjoy it while you can......my 20" WOA upper is almost finished......and I ordered a new scope!!!! ;)
Posts like this are so refreshing in here.......conjecture seems to be a prerequisite in the Tech section.
I love me some friendly competition. Looking forward to seeing some of your scores
the gun I am shooting was the first AR I built. I have learned a lot trying all the tricks I read about. I know a professional gunsmith can do a better job and I let them do my bolt guns but AR's are really toys and I like doing it myself.
that said I do have a Robert Whitley 6mm AR turbo 40 upper on the way. I expect when it arrives my scores will improve too!
by the way he laps the receiver face and uses Loctite.
FollowThru
08-11-15, 07:20
This fellow in his book recommends Loctite for a match AR: "The Competitive AR15 Builders Guide" Book By Glen D. Zediker
sevenhelmet
08-11-15, 09:54
Meh. Put me in the "ease of disassembly/barrel replacement" category. I'm not a good enough shooter to reap the most likely marginal benefits of a locktite job.
The 6.5 Grendel is a different animal than the 5.56 AR's I thought we were talking about. I think JP does more than a few kooky things with AR15's. If using some form of Loctite on every possible thread makes someone feel warm and fuzzy, they should rock on warm and fuzzily. It is still such an unnecessary and ill-advised way to install an AR15 barrel.
Agreed!
I know JP Rifles does a thermal fit of their barrels (with barrel extension) into their upper receivers. They heat one part and/or cool another. The exact process is a trade secret. But the end result is the fit is VERY tight. I believe they have even fired guns in private testing without the barrel nuts attached.
JP Rifles are known in the competition world for their super accurate ARs.
I've never Loctited a barrel extension into an upper receiver. But I would bet money that it does not hurt accuracy, and probably helps. I just don't think there is very much to gain, and would rather have a gun that can be detailed stripped/disassembled with no issues.
Joe Mamma
No one is saying it would hurt accuracy, but what empirical data can you (or anyone) provide that placing Loctite on receiver threads/barrel nut improves accuracy?
rcoodyar15
08-11-15, 11:55
Meh. Put me in the "ease of disassembly/barrel replacement" category. I'm not a good enough shooter to reap the most likely marginal benefits of a locktite job.
Now the AR15 I keep under the back seat of my truck or the one strapped to my pack for emergencies I would never glue.
but my range play toy that I will do most anything to shoot smaller groups with Oh Yes I glued it. If it screws it up totally I will throw it in the trash. I have a vltor mur at Kraiger for them to barrel now and a 6mm AR turbo on the way.
One of those should give me the groups I have been looking for.
rcoodyar15
08-11-15, 11:57
Agreed!
No one is saying it would hurt accuracy, but what empirical data can you (or anyone) provide that placing Loctite on receiver threads/barrel nut improves accuracy?
Well I would say this Saturday's range session will tell the tale
Good information in here for sure, and I think at the end of the day, we have established that there is no empirical data to support either side of the discussion. One thing I read though however, is the notion of using loctite on upper receiver threads when installing a BN. I'm no armorer, but I've assembled enough AR's and read enough about the topic to know this is probably the worst advice anyone can give.
When keeping the torque weight low on a gun that won't get hot, a drop of locktite on the threads will be more than enough to keep the barrel nut from coming loose on an upper that uses a barrel nut that doesn't have any other means of staying put other than torque itself.
Again I will reiterate that I would never do this on a hard use/defensive rifle.
For the record, I am an armorer and I work for a manufacturer.
I've shot a few Cory Builts. They are smooth, reliable and consistent
rcoodyar15
08-11-15, 17:33
Agreed!
No one is saying it would hurt accuracy, but what empirical data can you (or anyone) provide that placing Loctite on receiver threads/barrel nut improves accuracy?
I never said the barrel nut. I put moly grease on mine. Now cory's idea of putting a drop of blue on the barrel nut of a low torqued nut is a good idea. other than keeping the torque low this would not affect accuracy.
What I did was glue the barrel extension into the receiver with red Loctite. I feel a rigid connection at this point will effect accuracy. Too bad they can't thread the barrel into the receiver like they do a bolt gun. Bet that would help a bunch.
I never said the barrel nut. I put moly grease on mine. Now cory's idea of putting a drop of blue on the barrel nut of a low torqued nut is a good idea. other than keeping the torque low this would not affect accuracy.
What I did was glue the barrel extension into the receiver with red Loctite. I feel a rigid connection at this point will effect accuracy. Too bad they can't thread the barrel into the receiver like they do a bolt gun. Bet that would help a bunch.
What mysterious force is causing the extension to move within the receiver bore? How does barrel nut torque improve accuracy? You could easily build a receiver heavy enough to accept a threaded barrel extension but it would never be a bolt gun.
rcoodyar15
08-11-15, 19:08
What mysterious force is causing the extension to move within the receiver bore? How does barrel nut torque improve accuracy? You could easily build a receiver heavy enough to accept a threaded barrel extension but it would never be a bolt gun.
It is always humorous to start a thread on this forum about something different.
Lapping receiver faces comes to mind
now its is using loctite to glue in barrel extensions
I don't understand the reluctance to try new ideas
if you did a little research you would be surprised at the big name precision AR builders that do both of these things
they aren't going to advertise because these are the tricks of the trade. How you really get one dialed in.
I really don't know what makes people so reluctant to explore new ideas. Can you enlighten me? please don't quote me the milspec for an AR15. That really doesn't impress me. Now it does make all these parts interchangeable and I am thankful for that but there is much greater quality out there than milspec. Lots of new ideas too.
It is always humorous to start a thread on this forum about something different.
Lapping receiver faces comes to mind
now its is using loctite to glue in barrel extensions
I don't understand the reluctance to try new ideas
if you did a little research you would be surprised at the big name precision AR builders that do both of these things
they aren't going to advertise because these are the tricks of the trade. How you really get one dialed in.
I really don't know what makes people so reluctant to explore new ideas. Can you enlighten me? please don't quote me the milspec for an AR15. That really doesn't impress me. Now it does make all these parts interchangeable and I am thankful for that but there is much greater quality out there than milspec. Lots of new ideas too.
Enjoy your cool-aid. These big name gun plumbers that swear by it charge for it. Kind of like the paint protection package a car dealer sells you. It does nothing but boost their profit margin. Prove me wrong. Explain to me how it works. That is all I ask.
Just because companies or builders do something, doesnt mean it works. Doesnt mean it causes harm, either.
For one, if they charge $10, or $20 or more to put half a dozen drops of loctite on a barrel extension, they are making a good profit on it.
So, if the barrel extension can and is moving about in the receiver, then yes, loctite will fill that space. However, most loctites get somewhat hard, even brittle, when cured. Aluminum grows faster than steel when heated. Larger diameters grow more than smaller ones. This means that the diameter of the receiver bore will grow faster, and more, than the barrel extension. Loctite will not stop this. What this amounts to is that the loctite will crack, and become not attached to the receiver bore, and likely not attached to the extension either over time. Some may even work its way out into the bolt carrier area.
Interference fit of the two parts will accomplish more, as the initial growth will not at first loosen anything, until the growth exceeds the amount of interference fit.
Really, of you got almost .004" of slop in the fit, youre probably better off wrapping the extension with a piece of shim of either brass or steel, to get a tight, tap in fit.
If the loctite does anything, the cushioning effect on the harmonics is probably the most.
Anytime the receiver must be heated to install the barrel, adding loctite is pointless. The receiver will cool and push it out before it has time to fully set up.
Some loctite versions are softer than others, so maybe some builders are hoping the softer versions will crack and seperate less.
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You have to keep in mind a manufacturer can order hundreds of uppers, barrel extension, bolts etc. They can fit everything and swap parts around to get things exactly how they want them. Home builders don't have that luxury. I've had uppers which were so tight I had to place them in the oven to get a barrel to seat. Others that were so loose it was almost comical. By keeping that tool (use of loctite) in the toolbox, you can be assured of having the fit you want.
...Too bad they can't thread the barrel into the receiver like they do a bolt gun. Bet that would help a bunch
Actually, this would be a bad thing. The upper does nothing but hold part in place. Threading the barrel directly to the upper would unnecessarily complicate installation and would not hold the barrel assembly as securely. Remember, the upper is made of aluminum. You would be then be using aluminum threads. Threading the barrel into the aluminum threads will lead to the barrel squirming in the upper
I remember once that I said a prayer before I built a rifle. It did some amazing feats and the accuracy was pretty solid.
rcoodyar15
08-12-15, 04:18
Actually, this would be a bad thing. The upper does nothing but hold part in place. Threading the barrel directly to the upper would unnecessarily complicate installation and would not hold the barrel assembly as securely. Remember, the upper is made of aluminum. You would be then be using aluminum threads. Threading the barrel into the aluminum threads will lead to the barrel squirming in the upper
can't thread the barrel into aluminum. The barrel extension is steel for a reason. yes the upper supports the barrel. Imagine the leverage a 26" 5.5# barrel has on that receiver.
Just because companies or builders do something, doesnt mean it works. Doesnt mean it causes harm, either.
For one, if they charge $10, or $20 or more to put half a dozen drops of loctite on a barrel extension, they are making a good profit on it.
So, if the barrel extension can and is moving about in the receiver, then yes, loctite will fill that space. However, most loctites get somewhat hard, even brittle, when cured. Aluminum grows faster than steel when heated. Larger diameters grow more than smaller ones. This means that the diameter of the receiver bore will grow faster, and more, than the barrel extension. Loctite will not stop this. What this amounts to is that the loctite will crack, and become not attached to the receiver bore, and likely not attached to the extension either over time. Some may even work its way out into the bolt carrier area.
Interference fit of the two parts will accomplish more, as the initial growth will not at first loosen anything, until the growth exceeds the amount of interference fit.
Really, of you got almost .004" of slop in the fit, youre probably better off wrapping the extension with a piece of shim of either brass or steel, to get a tight, tap in fit.
If the loctite does anything, the cushioning effect on the harmonics is probably the most.
Anytime the receiver must be heated to install the barrel, adding loctite is pointless. The receiver will cool and push it out before it has time to fully set up.
Some loctite versions are softer than others, so maybe some builders are hoping the softer versions will crack and seperate less.
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Not saying that LoctiteŠ on your extension is a good or bad thing....
I do know a bit about anaerobic methacrylate-based adhesives. They are pretty good at handling different rates of thermal expansion, provided the diametrical difference doesn't get to big, about .001" to .002".
How hot would your upper have to get to have the 1.000 inch bore grow .001"?
Interesting question, the aluminum bore is a thick walled tube, and partially contained by the steel barrel nut, so, the aluminum bore under the nut won't increase in diameter more than the barrel nut. You are not going to see a change in the diametrical clearance between the upper and the barrel extension at temperatures less than 350°F - 400°F, and at these temperatures, the LoctiteŠ will break down anyway.
BUT, the LoctiteŠ doesn't disappear, it will still take up space acts a shim.
Yeah, I can see how it might help, but, like facing off the front of the upper, the improvements will be very small, and most people won't see ant difference unless they are shooting off of a machine rest on a concrete pad...
can't thread the barrel into aluminum. The barrel extension is steel for a reason
As you know this already, why do you keep advocating threading the barrel directly to the upper?
rcoodyar15
08-12-15, 08:49
The anschutz 54 is known for its accuracy. It too is a .22 caliber with a slip in barrel. I have attached a link of how builders are rebarreling these actions. Kind of interesting.
http://www.rimfireaccuracy.com/Forums/showthread.php/2481-Using-loctite-in-anschutz-barrel-installation
A 22lr and a 5.56 isnt going to be a very close comparison.
Looks like the anschutz is normally pinned, not clamped in with a barrel nut. Also, recoil is different. Heat will be less.
Loctiting on the ar may do something for some. It wont fill large gaps and stay. It wont be present if there is no gap. Its still a glue, and compressible. The thicker it is, the more compressible it is. How much the metal expands has been said to be very little, and of no consequence, 001" or less. However, this thread is about filling just such a space to try for more accracy, so apparently, it is of consequence to somebody.
We are down to minutia (sp?) here as it is, unless you are putting together a top of tolerance receiver with a bottom of tolerance barrel extension. At that point, there is room for a metal shim, which is always more solid than a plastic glue.
But, metal wont absorb harmonics, just transfer them.
I seriously doubt it does very much. As pointed out, enough to be noticed by the majority of shooting conditions.
Threading it in does complicate things, but they can be overcome. Other rifle systems have threaded in barrels that do line up correctly. However, the steel threaded into aluminum issue remains.
Really, all of this skips the fact that the thinnest, and likely weakest point is the section of receiver behind the threads, where it is undercut. The barrel extension goes only a little past this point, not enough for any glue to stabilize any flex of that section.
I dont know of any tests offhand to see about flex in that section, but it is the thinnest part of the equation. The reverse barrel nut receivers have way more material at the barrel/receiver junction, would be noticeably more rigid.
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A 22lr and a 5.56 isnt going to be a very close comparison.
Looks like the anschutz is normally pinned, not clamped in with a barrel nut. Also, recoil is different. Heat will be less.
Loctiting on the ar may do something for some. It wont fill large gaps and stay. It wont be present if there is no gap. Its still a glue, and compressible. The thicker it is, the more compressible it is. How much the metal expands has been said to be very little, and of no consequence, 001" or less. However, this thread is about filling just such a space to try for more accracy, so apparently, it is of consequence to somebody.
We are down to minutia (sp?) here as it is, unless you are putting together a top of tolerance receiver with a bottom of tolerance barrel extension. At that point, there is room for a metal shim, which is always more solid than a plastic glue.
But, metal wont absorb harmonics, just transfer them.
I seriously doubt it does very much. As pointed out, enough to be noticed by the majority of shooting conditions.
Threading it in does complicate things, but they can be overcome. Other rifle systems have threaded in barrels that do line up correctly. However, the steel threaded into aluminum issue remains.
Really, all of this skips the fact that the thinnest, and likely weakest point is the section of receiver behind the threads, where it is undercut. The barrel extension goes only a little past this point, not enough for any glue to stabilize any flex of that section.
I dont know of any tests offhand to see about flex in that section, but it is the thinnest part of the equation. The reverse barrel nut receivers have way more material at the barrel/receiver junction, would be noticeably more rigid.
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Well, some people are on a Holy Quest to make a 0.1 MOA rifle...they'll try anything, I suppose.
This fellow in his book recommends Loctite for a match AR: "The Competitive AR15 Builders Guide" Book By Glen D. Zediker
Clint McKee (Fulton Armory) Does in his book also
I use blue on my Grendel build too..after a 1000 rounds,about 400 suppressed I took it apart...had to use some heat gun but there was still plenty of loctite there.. I cant tell if it makes a difference but the gun was a 1/2 moa build so I can't tell if it worked but it doesn't hurt anything to try it... but I would never put on the threads like KAC
I remember once that I said a prayer before I built a rifle. It did some amazing feats and the accuracy was pretty solid.
Nice!
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