Now, good group? The guns I build shoot under half an inch. Well that is true for the bolt guns but since I have started building double rifles we have to comprimise that is not a bad group! When working up your hand loads use a cronograph as your rifle was regulated for a given load and velosity. If your velosity is under or over the stated velosity for that cartridge then you are either over pressure or under pressure. With the 450#2 you will want to use a filler for your your loads and I have found foam works great and you do not have to weigh it like you do with other fillers. The .450 # 2 is a great cartridge and you will have a great time with your rifle as I do with the one I built. If I can be of any help with your loading or other wise please feel free to contact me!!!!