2aHawaii

Tools and Uses => Firearms and Accessories => Topic started by: Vbc on April 07, 2021, 08:02:07 AM

Title: AR15...shim a barrel extension
Post by: Vbc on April 07, 2021, 08:02:07 AM
anybody did it? is it worth it and did it help grouping? looks easy on youtube. I have 3 uppers and would like to give it a try.
Title: Re: AR15...shim a barrel extension
Post by: ren on April 07, 2021, 10:18:14 AM
Tried it with not much testing. Glued an upper with threadlocker red. A better way is to get a slight oversized ext from Compass Lake or White Oak. Another option is to get a slightly undersized upper from BCM. Heat to fit.
Title: Re: AR15...shim a barrel extension
Post by: aaronc5362 on April 09, 2021, 01:34:05 PM
I never shim a barrel before but have use loctite red and blue. Recently i bought loctite 620 as ive heard its the best for it. Never had a chance to try it though. I dont think ill be piecing any ar15 uppers anytime soon. Tired and things are hella expensive now.
Title: Re: AR15...shim a barrel extension
Post by: robtmc on April 09, 2021, 05:39:51 PM
Remember Kuleck and McKee's first book mentioning locktite on the barrel extension to receiver in an accurizing chapter.

No comments were offered whether it was worth the bother.  No anecdotal comments as far as I know, but never really looked hard.

Suppose my innate urge to fiddle holds me back from trying,   
Like to re-arrange parts too much to locktite anything. 
Not to mention no decent rifle range to test it on.

Would try it on a .308, on a 5.56, why bother?
Title: Re: AR15...shim a barrel extension
Post by: Mdotweber on April 09, 2021, 05:58:48 PM
Is this for a hyper accurate bench queen Ar? Shimming/glueing a barrel ex, glueing gas blocks ect. will show a negligible often unmeasurable increase to the accuracy of your ar rifle. Good custom build loads and practice is the way to achieve tack driver status with your setup. If you're like me and just want an excuse to fiddle, grab some loctite and go to town but don't expect any miracles and take care to not over do it and muck up your gas hole.
Title: Re: AR15...shim a barrel extension
Post by: Heavies on April 09, 2021, 06:13:22 PM
I've done it, but have not evaluated if it makes any difference.  The rifle is a 6.5 Grendel and shoots about .75 MOA.  Made me feel better that the barrel wasn't sloppy in the upper, but in reality the AR platform is so loose in all it's components, just shimming the barrel and not addressing everything else, I'm not convinced it helps to a measurable degree.
Title: Re: AR15...shim a barrel extension
Post by: robtmc on April 09, 2021, 07:56:29 PM
but in reality the AR platform is so loose in all it's components, just shimming the barrel and not addressing everything else, I'm not convinced it helps to a measurable degree.

Yeah, fer crissake, this is not a platform intended for benchrest competition..