Posts: 8
Threads: 3
Joined: Jan 2015
Hello
Just got my Criterion barrel and test fitted to my billet upper. I can slide the barrel in without any resistance and wobble the barrel back and forth. I measured the barrel extension and ID of receiver and it is around .006" difference. Would you get another upper or try bedding with loctite?
thanks for any info
Posts: 990
Threads: 14
Joined: Sep 2014
Bed it. Most receivers are gonna be that way. If you have a lathe you can cover barrel extension with devcon and machine to precise fit, but that's kind of a pita
Richard
Member since 2011, data lost in last hack attack
Posts: 271
Threads: 2
Joined: Jan 2015
Posts: 1,143
Threads: 51
Joined: May 2012
blue locktite bedding and torque the barrel nut on and if you ever want to remove it you will need to either heat it or pound the barrel out....... i put blue locktite on my extensions and antisieze on my barrel nuts then follow the torque to 35 pound 3 times procedure to seat the threads and then torque to 50-80 where ever the hole lines up to put the gas tube through
Punctuation is for the weak....
Posts: 8
Threads: 3
Joined: Jan 2015
What is the optimal torque for accuracy ? I have a Geissele Mk1 rail so I don't need to line up the barrel nut.
Posts: 1,143
Threads: 51
Joined: May 2012
Punctuation is for the weak....
Posts: 17
Threads: 5
Joined: Oct 2012
I had the same problem with a build recently, but the gap wasn't that big. I tried using blue Loctite, but I my groups would have 2 shots within 1/2" and a flier at least an inch away. I realized that I was asking too much for the barrel nut and the small flange to hold against the whipping of a 22" barrel. My solution was to wrap the barrel extension with shim stock, then apply some blue Loctite as a lube and slide it in. the rifle now shoots 1 1/2" at 200 yds.
Since I had to buy a piece of SS shim stock .001" X 50" X 6" I would be willing to sell you a piece 12" long for $5 plus S&H. I don't know what S&H will be, because I'll have to put it on a roll, as it cannot be folded. If interested, let me know and I'll check on the S&H.
Life is too short for cheap rifles, cheap bourbon, or cheap women.
Posts: 24
Threads: 2
Joined: Nov 2015
05-24-2016, 10:16 PM
(This post was last modified: 05-24-2016, 10:19 PM by rothirsch.)
Try using loctite 640. It's ment for high temp beding, if the gap is huge you could try 680.
http://www.na.henkel-adhesives.com/indus...aceted%7C#
Posts: 311
Threads: 19
Joined: Sep 2014
I disagree. Tight is right. Had the same issue. Sloppy fit, barrel would now stay bedded. Loctite kept breaking loose. Ended up getting another receiver.
My thoughts, bring in your barrel with you to the gun shop and try the fit.
Posts: 8,507
Threads: 241
Joined: Sep 2014
You can fit receivers from a larger sample of uppers to work with, or do one of several other methods.
I personally Cerakote my uppers and build up material inside the extension tunnel, as well as use Blue Loc-tite and high torque, at least 65 ft-lbs.
I also square the receiver face with the lapping tool.
You can use shim stock, interference fit, or thermo-fit too.
NRA Basic, Pistol, Rifle, Shotgun, RSO
CCW, CQM, DM, Long Range Rifle Instructor
6.5 Grendel Reloading Handbooks & chamber brushes can be found here:
www.AR15buildbox.com
