09-06-2021, 07:33 PM
TLS, the RCBS Base Size dies size to SAAMI minimum, while I think it's probably safe to assume that most chambers are reamed near max. The base sized virgin brass vs larger diameter sized brass is why it's a little pointless to do load development with virgin brass - case capacity will change as well as the pressure curve as the base sized brass needs to expand more to fill the chamber. I used to base size some .223, but it resulted in more frequent trimming.
#FJB