The SOLGW PRECISION barrels are unquestionably the most accurate barrels they've ever offered. Optimized for accuracy, the SPR contour and 5/8A-24 threads at the muzzle are by no means lightweight, but they are routinely shooting 1/2MOA groups with multiple types of ammo. The PRECISION series is 416R stainless steel, black oxide coated, and cut with polygonal rifling. Please note that these barrels will have a shorter lifespan than the 4150CMV barrels, however the SOLGW warranty still applies. If you can manage to shoot one out, they'll still replace it for you free of charge. Mfg: Sons Of Liberty Gun Works