91 Mauser chambering problem

[MEHavey]

Get a PrecisionMic headspace gauge from RCBS and compare the as-fired headspace vs the as-resized headpace. Then you have the info for some follow-on decisions.
Real Guns

Depending on what you find, realize that even necksizing-only results in gradual lengthening of the case -- especially with a conventional reloading die. So after you find out how much you need to "bump" the as-resized headspace down, consider machining/belt sanding the shellholder face down a few thousands to compensate**
-- OR --
Get a Redding shellholder set that compensates for any number of out-of-spec conditions
shellholders.html

**(Make sure you tag it/keep it separate)