Thread: Shoulder Bump Advice

Originally Posted by Sonicjoe

Just after some advice for shoulder bumping brass.

I'm shooting 7mm Rem Mag, which after firing measures around 2.1200" with a headspace comparator.

I also tried some various lengths of brass in my chamber (firing pin out of bolt):
2.1200 inches chambers fine, bolt handle falls down
2.1215 inches chambers fine, bolt handle falls down
2.1230 inches chambers fine, bolt handle has slight resistance
2.1235 inches won't chamber

After resizing, my shoulder is growing out to 2.1230" - which still technically chambers, but is close to not.
I assume this will also cause an issue with the brass moving back and forth a lot.

So, I'm after advice:
What length should I be aiming my shoulder bump to be? 2 thou less than the fired length (2.1200") or the size that won't chamber (2.1235)?
I assumed screwing my die down would help move the shoulder back (rather than make it longer), but I'm already hard on the shell holder. Help?

Hopefully that's enough info! Can provide more as needed.
Cheers

I don't know what the issue is bud but I do know the rem mag with that belt can be problematic. Mine has a really loose chamber and my Redding body die would really struggle with resizing the brass while my Lee die was obviously a bit looser and was better, maybe excess brass is flowing into length.
Very soon the brass developed a bulge in front of the belt which made chambering difficult...sounds like you are doing some good measuring son that's not the issue.