The Firing Line Forums - View Single Post - Sizing Blinged LC 7.62 Brass in a Summit and a RockChucker II.

GWS · April 3, 2014, 01:11 PM

Thank you sir! (except you missed some....maybe a cut & paste would work better?)

I'm really getting an education (or more confused) with this....I'm finding out some more things about multi- sizing. For one thing the dimensions continue to change!? Spring back changes, perhaps.

I was using a Wilson gage to keep brass within reason, but I didn't really measure anything......shoulda.

Focusing on sizing this (most likely) MG brass and getting it to gage right in the Wilson, I didn't focus on how far I was bumping the shoulder. (not concerned terribly because this was a test batch) Most of it was bumped too far back according to my RCBS Precision Mic....like .007"...more than I like. (still looks good in the Wilson, so here's a new realization that the Wilson gage is a pretty course measurement.

One of the things I noticed in setting up the Summit Press, long side the Rock Chucker, (besides the fact that shims are necessary to move a die back and forth between them) is that the Summit required twice the "cam-over" than the Rock Chucker to bump the shoulder enough to settle the case rim flush with the max surface on the Wilson. ?????? haven't a clue why?

Then after miking the cases on the RCBS tool after each sizing I am noticing that the shoulder continues to bump more (at the same die setting) ..... even the minor sizing done in steps 4 through 7 on my list!

So I can size once on the R.C. and have the shoulder pushed back .002.....runout improvements in steps 4-7 pushes the shoulder back another .005???

Sizing once on the Summit (same cam-over feel!) shoulder is not bumped at all, but steps 4-7 pushes the shoulder back .003.

Talk about a can of worms.

Anybody make sense of this?

April 3, 2014, 01:11 PM	#33
GWS Senior Member Join Date: September 8, 2010 Location: New Mexico Posts: 688	Thank you sir! (except you missed some....maybe a cut & paste would work better?) I'm really getting an education (or more confused) with this....I'm finding out some more things about multi- sizing. For one thing the dimensions continue to change!? Spring back changes, perhaps. I was using a Wilson gage to keep brass within reason, but I didn't really measure anything......shoulda. Focusing on sizing this (most likely) MG brass and getting it to gage right in the Wilson, I didn't focus on how far I was bumping the shoulder. (not concerned terribly because this was a test batch) Most of it was bumped too far back according to my RCBS Precision Mic....like .007"...more than I like. (still looks good in the Wilson, so here's a new realization that the Wilson gage is a pretty course measurement. One of the things I noticed in setting up the Summit Press, long side the Rock Chucker, (besides the fact that shims are necessary to move a die back and forth between them) is that the Summit required twice the "cam-over" than the Rock Chucker to bump the shoulder enough to settle the case rim flush with the max surface on the Wilson. ?????? haven't a clue why? Then after miking the cases on the RCBS tool after each sizing I am noticing that the shoulder continues to bump more (at the same die setting) ..... even the minor sizing done in steps 4 through 7 on my list! So I can size once on the R.C. and have the shoulder pushed back .002.....runout improvements in steps 4-7 pushes the shoulder back another .005??? Sizing once on the Summit (same cam-over feel!) shoulder is not bumped at all, but steps 4-7 pushes the shoulder back .003. Talk about a can of worms. Anybody make sense of this?