Most proofs are 4 land rifling, vs the 5 of most competitors, could be the difference. My 7 lrm barrel is bout to go in the scrap heap. I'm trying to decide between 28 nosler, 7mm blaser(improved maybe) and 7/300wsm. 28 nos is a bit overbore, however it lasts as hunting rig.I know! My other 7-300s were on Benchmark and Bartlien, and accuracy on those always settled in about 3000fps @ 66.8 - 67.4grs of H1000, hitting pressure @ 3100ish. I don't know why my proof barrels always seem to do the same speed or more with less powder and have a higher pressure threshold, but they always do. So I keep buying them