While obviously the cartridges (eg, .450/500, 470, 475 No 2,...)are not interchangeable from practical standpoint there is no difference (slug of 480gr to 500gr with avg Vo of 2100+/-100fps), but before you buy any NE express rifle make sure ammunition and or components for reloading are readily available. A "wall-hanger" is worth a lot less than rifle that can be shot and used in the field. wink