Thread: Re-chambering a new factory bbl

Thanks @gundoc, I understand the difference in twist rates and potential benefits for heavier pills but the 1:9.35 or 1:9.5 twist rate barrels (REM & Tikka) are quite capable in 7RM of producing good accurate loads with 160-168gn pills. My interest and question is more a technical one regarding the engineering aspect or feasibility of modifying a 7RM chamber to convert to 7PRC. Yes one could start with a brand new 7mm blank but I would like to understand the feasibility of the 7RM to PRC change. Looking at SAAMI specs it seems that if you lopped off 7RM cartridge immediately in front of the belt then you’d be close to 7PRC dimensions albeit with less taper & steeper shoulder in the 7PRC. Both differences I assume would be rectified with a 7PRC reamer.
I won’t digress into a performance debate on 7RM vs PRC, but my thinking based on experience with lots of different 7mm cartridges is that the PRC should be less affected in going to shorter bbl (20in). Less taper & more efficient cartridge. Some of the limited data published about 7PRC seems to support this extra potential