I have bought 6 barrels or so from Ritch over the years. I have had him make me 20P , 223, 6x45 and 6x6.8 barrels all P3 grooved and from 20" to 24" depending on my builds, heavy sporters at .690" and they have all shot sub moas and still do when Im not trying to shoot in 30 mph winds out here. He was making Black hole barrels a time back, then went his own way. GL shooter use's all of his barrels/builds iir.
Ive never had copper problems with the P3 grooved barrels.
He will gladly talk to you on your requirements when you get him on the phone.