There are several of you folks that I need help from regarding my Disc Extreme for which I have converted to bare 209s with the Lehigh product. After reading everything I could find about ignition, blow back, primer crush etc., I decided to try Remington STS primers. I purchased some of the shimming washers recommended for obtaining adequate primer crush. Per suggestions I was shooting for .003 to .005 of crush.
So I started by checking primers for length and got .292, .293, and .294. Nicely consistent. Tried a .294 length for crush and none was measurable. But it was oddly difficult getting the bolt started rearward.
Put a .241 x .005 shim and was surprised to find that it was tight in the bottom of the primer pocket. Tried a couple more .294s and got about .001 of crush. Very hard to start it the bolt rearward!
BTW, I found that it is very tricky measuring the part of a primer that actually gets crushed since the crushed part is barely inside the outer edge. Checked the primer pocket I.D and found it to be .239(?) Checked my primers and they run consistently .241. Tried to insert a primer by hand and no go. I should add here that the bolt does not close hard.
Added a second .241 x .005, the bolt was nearly impossible to start rearward and the crush was about .005 more as expected.
At this point I was thinking that the primers might be crushing end wise AND expanding in girth which would explain the difficult extraction. I picked out the shims and tried a .248 Dia. to see if they were even useable. I tapped one in gently a little bit using a sanded down 1/4 in. Dowel. Predictably the .248 shim was deformed and not going to be usable. I will of course shoot this rifle a few times without shims and see if the tight primer pocket was by Lehigh’s design. If minimal blowback without shims I may find that I need need not shim with the right primers.
Whaddya think?