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Old February 16, 2012, 06:29 AM   #10
Senior Member
Join Date: November 13, 2006
Posts: 5,249
While the advise to set for bump off the shellholder is typically in the die instructions,it is poor advise.It does overwork the brass.

Every decent gunsmith uses a set of headspace gages when he chambers the rifle.Its one of the critical dimensions,that has to be right.We expect that,correct?

Every time we set up our reloading dies,we are establishing exactly the same mating dimension in our ammo.It is a good practice the take the same care "headspacing" our ammo.

As a kid of about 17,I would candle smoke the shoulders of fired cases,very slowly creep the die down till the smoke showed contact,then use feeler gages to determine the shellholder to die clearance.Then a feeler gage and that shellholder went in the die box.And,it was time to clean the soot out of the die.It is not a great method,but I was rocking my 7 mag and needed to control it.That was 42 yrs ago.

Today,OP,you might consider an RCBS Precision mic.You use it to measure a fired case,and set back the shoulder a measured amount,such as .002 in a bolt gun.

A bushing gage lets you size to a hi-lo limit,and make SAAMI length cases.That can be narrowed by using a measuring tool,such as an indicator withn the bushing.

I also have a setup with a granite comparator stand and a travel indicator.A datum id bushing is attached to the threaded indicator spindle.Same idea as the Hornady Lock-n-load,I'm just using a comparator stand and indicator rather than clamping it on calipers.

OP,you have the right idea.See if you can find Precision Shooting Guide to Reloading for Competition.
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