I have a 6mm CM RPR that I bought for my son.(I would assume Ruger uses the same reamer and barrelas the PRC)
I bought 100 rounds of Hornady 108 ELD to break the barrel in and I couldn't believe the accuracy I was getting.
I shot a 2" 4 shot group at 600y with it. The first round was only 1.5" out of the group which made the overall 5 shot group 3.5" at 600y.