Not saying that Loctite© 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 Loctite© will break down anyway.
BUT, the Loctite© 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...
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/Forum...l-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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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
Last edited by cst; 08-23-15 at 22:19.
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