Upper Receiver????

[A5BLASTER]

Bill Alexander
07-25-2012, 10:38 AM
For a GRENDEL build the finished barrel nut torque when everything is aligned should not be less than 60 ftlbs.

We employ Loctite 243 to bed the barrel extension to the receiver. We have the option of running the receiver bore tight and still use Loctite due to the structure of the surface coating on the receiver and also the imperfections that may be present in the barrel extension. With CMM data one finds they are rarely round.
For receiver threads we will employ the same Loctite for assembly. Early work with the cartridge, especially hotter loadings found it is possible to create radial movement of material and flex the assembly. Most times this is not problematic but in mass production one cannot tolerate +10% of accuracy failures due to this effect. Loctite in the threads removes this problem. The grade used is a removable type so anyone proficient with mechanical assemblies will not have problems. The material provides a better long term joint for both durability and also corrosion.



"I personally never used blue loctite on my barrel nut threads, but did use the higher torque value Bill recommended."

Thank you that is the statement from Bill. I was looking for.

He clearly states, he did what he did too hold accuracy standards he wanted in his mass produced rack grade guns.

By all means a person can use as much torque as they wish. But with today's barrel nut tech. There is simply zero need to use such high torque on such a fitting.

But I also do lapp my uppers and bed my barrels with shim stock useing the heat and freeze method. Maybe that effects my results. I have done this low torque with high end PF barrels as well with BFT'S rack grade barrels and my 26 gpc wildcat barrels. And all of them shoot sub moa (as long as I do my part) and some of my handloads are a bit spicy. Not dangerously spicy but past 52k pressure for sure.

It's a easy thing to test if one wish's to do so on their own guns.