03-14-2014, 08:06 PM
My guess would be due to the different reamers used to cut the chambers. A brand new reamer may be ground to the +0.002" side to the SAAMI spec in the throat portion and would still be within spec. Then have another reamer that is well used and is now 0.000" to -0.001" in the throat and needs to be reground. Just a guess on my part.
pds
pds

