Once ya get above about 60-65gns youl need a good fast twist barrel like a 1 in 8" or 1 in 7". We use a standard twist(1in12") Sako A7 with the berger 64gn projectiles. these are as heavy as we could go with our barrel. they shoot great(1/2MOA) and are great on small game aswell. devistating on wallabys,hares,rabbits and magpies.
heres a vid of them in use