Originally Posted By: hm1996
I do not have any fired brass left to measure but a new, unfired FC neck measures .2815 and a dummy case made from a fired FC case measures .282 (both chambered in my rifle easily).
Have you tried painting a case with sight black or a black marker then break the rifle open and chamber round by hand until it begins to feel snug; remove and see where the friction is just for kicks?
Regards,
hm
For the most part, measuring brass extracted from a gas-operated weapon is an unsure science at best. The neck diameter especially can and does get to be larger in diameter than the chamber from which it was extracted.
I had been hand-loading literally my entire life when the WSSM came along. It just about killed me! I ended up making a device much like the RCBS precision case micrometer, and that allowed me to troubleshoot, and fix my reloading problems.
The problem is that folks get by with making small mistakes on the .223 for the AR and everything still runs fine. On a .223 case if the shoulder is not set back far enough, and the brass is 1/2 a thousandth of an inch longer than the chamber, the heavy BCG will "smash" the case into the chamber, the bolt will close, and no one will be the wiser. Not so on a WSSM. If that case, as thick and as large in diameter as it is, is 1/2 of a thousandth of an inch longer than the chamber, the bolt just STOPS!
After licking my wounds 15-18 years ago, I wrote a two-page letter that we make available to WSSM users to help them troubleshoot their loading techniques.
This particular upper we actually have a fair amount of history on: We built it for a guy that wanted to shoot long, heavy bullets, so it started life as a 1:8 twist, 24" barrel. The original customer had no problems with accuracy or feed/function. He ended up selling the upper to another person that wanted to shoot light bullets, and thought he was getting the correct twist. The new owner sent it to us to have it cut back to 22" and fluted. We did so, tested it and returned it to him. It fed and functioned flawlessly, but he just wasn't able get the light bullets to shoot the way he wanted, so he ordered a 1:12 twist from us and sold the 1:8.
When Varminter .223 spoke with me about it, he mentioned that it had something in the chamber that was scratch the brass. I talked him through what I thought he should do, but he thought there was still a problem, so he sent it to us.
I borescoped it, and wasn't able to see anything that might scratch brass, but I lightly lapped it with a fine ball-hone, then tested it with factory and handloaded ammunition. We even took it to the range and shot groups with it. The upper not only fed and functioned as it should, it had good accuracy.
We have not received a call, message or email about any problems with it since we returned it. My partner just happened to see this thread and bring it to my attention.