Finally got to shoot the 450B today. The barrel is a 17.5" varmint. It does show some decent accuracy, but I think I will need a Ross brake on it to shoot it well. Recoil was not bad but the barrel really jumps up and my wrist is sore after about 25 rounds. I will post pics after I get the brake and paint it up. It is a fun project though.
Loads were with 240 XTP Mag and IMR 4227.