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.
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.
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.
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.
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.
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.
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.
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.
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.
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:
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.
