Used PVA Osprey prefit in 6mm BR for ARC Nucleus/Archimedes - 26", 1:7.5 twist, M24 contour, 5/8x24 threads. Per original owner, 385 rounds fired & shot under 1/2" MOA with 30.2gr (Varget or XBR). Only reason I decided not to keep is that I picked up a 6 br barrel for my AI and I don't need...