Johnny2,

The Great Plains Rifle has a 1 in 60 round ball twist. The Great Plains Hunter has a 1 in 32 twist which allows the heavier conicals and sabot rounds to stabilize. The 2 barrels can be swapped in the same stock so it gives you the ability to use the one you want without having to buy the whole gun. I bought the 54 GPR then added the 50 GPH barrel to have the best of both worlds.