Case shoulder – Bump Back

[ExtremeX]

How do I measure how much I bumped back the shoulder of a case?

My trimmer indexes off the case shoulder and I want to confirm I am within the acceptable tolerance before I start trimming.

[RandyD]

I too have a trimmer that indexes of the datum line of the case's shoulder. Despite this, trimming only affects the Over-All Cartridge length. I would measure the cartridge's over all length, trim to desired length and verify that you are within tolerances of the over all length. The primary goal is to get uniformity, not a specific measurement.

[17+1]

How do I measure how much I bumped back the shoulder of a case?

My trimmer indexes off the case shoulder and I want to confirm I am within the acceptable tolerance before I start trimming.

Have a case gauge?

I mainly shoot gas operated rifles, so I size to a case gauge so the reloads are guaranteed to run fine in all of them, whether I'm shooting a rapid fire or single load stage. Maybe shortens brass life slightly, but PMC/Winchester/etc. brass is essentially disposable after a couple reloads in a gas gun if you're shooting stiff charges.

You can always use your rifle chamber to see if the cases were sized enough. Usually that would help you in setting up your dies though, not acting as a go/no-go gauge. Scrub the chamber out good before hand.

[RandyD]

To measure a case using the datum line on the case shoulder, use this tool; RCBS Precision Mic Cartridge http://www.sinclairintl.com/.aspx/pi...Headspace-Tool

Again, trimming only affects the length of the neck of the cartridge and the only practical means of taking a measurement is to measure the over all cartridge length.

[ExtremeX]

To measure a case using the datum line on the case shoulder, use this tool; RCBS Precision Mic Cartridge http://www.sinclairintl.com/.aspx/pi...Headspace-Tool

Again, trimming only affects the length of the neck of the cartridge and the only practical means of taking a measurement is to measure the over all cartridge length.

Thanks for the link, I like this tool, might have to get one.

[gunboat]

A forster, lyman, or dillon case gage will usually suffice.
What case is in question?

[ExtremeX]

A forster, lyman, or dillon case gage will usually suffice.
What case is in question?

Mix of .223 / 5.56 cases