I am in the process of assembling a 6.5 Grendel AR and have been taking a more in depth look at getting as much accuracy as possible out of it. While looking at ways of tightening up the fit of the barrel extension into the upper receiver, I came across the use of stainless steel shim stock. Has anyone used this method? I originally considered using the locktite method, but would much prefer to try the shims. If anyone knows of a local source for smaller amounts of .001-.005 I would be interested in that as well.