Originally Posted by SDHNTR
Originally Posted by Yondering
Originally Posted by Craig2506
Think I have to agree with bsa...I’m over thinking it. I’ll just FL size next time and then go back to the collet.

Craig


Yup, do that and leave the expander ball in the FL sizer. Just try not to bump the shoulder back more than necessary. 1/8 turn of the die is the difference between not enough and too much, so some of us prefer to measure shoulder bump to get it right.


I don’t have the tools to measure, so I just mark up the shoulder with a dry erase marker, and then adjust the die so that it just kisses the shoulder and removes some of the marker. On my RCBS dies, that’s just a slight 1/16 more turn.
Sound about right?


A true 1/16 turn is about right, equivalent to .004" more shoulder bump, although it can be pretty hard to really judge 1/16 turn accurately.

If you have a digital or dial caliper and a piece of fired 40 S&W or 10mm brass though, you have the tools to measure shoulder bump. Really any piece of round tubing that fits approximately in the middle of the case shoulder works for measuring shoulder bump. Zero the caliper on fired brass from your chamber, and compare the same reading on your sized brass.

This pic is with a piece of .357 Mag brass, same idea. This piece of 6.5 Creedmoor brass has the shoulder bumped back .003".
[Linked Image from i.imgur.com]

Last edited by Yondering; 09/16/19.