What is interesting is this is the first time I ever heard of a factory die setting a shoulder that far back.
I have about 60 sets of dies and normally what happens is the case is run in till die touches shell holder and when pulled out it is obvious die is chambered too deep and the shoulder is not touched and the die stops sizing the neck before it gets to the base.
The guy that trained me said he noticed this back in the 50s and he would occasionally have to take his dies in to Springfield Armory where he was allowed to use the machine shop equipment after normal working hours.
He said he normally took off .005" for a first look and that "cleaned up" most of them by allowing the case to travel another .005" up into die so case shoulder would contact die shoulder and be set back.
I estimate I have had to trim about 15 of my dies in this way to get them to size and one had to be shortened .025" to get it to size properly. When I sized with it the base would get squeezed in and the shoulder went forward and made for hard bolt closing. When I removed the base material in several stages the shoulder was not moving until I got up to .025 and then it showed contact with shoulder and I haven't had problems with it since.
I use Mo Gages which allows me to set dies so shoulder is bumped back about .001". I have had friends send me their dies that showed this problem and I trimmed theirs and no more problems.
I have a 7.5 Swiss chamber reamer and I may just have to make a 7.5 adapter for the MO Gage some day. Right now my dies size just fine for the K31 I have.
Another thought just hit me. I remember hearing about the 1911 Swiss rifles which were rear lockers and such are known for bolt flex which allows the shoulder to go forward more. I guess there is a chance his dies are set up to correct such?????
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