Hey nothing like a good hunt for an excuse for buying a new rifle.
However, no matter what you use it is likley to blow right through an antelope unless it's waaaay out there. If you don't buy another rifle I wouldn't change loads in that 7mm Mag. if the BT's are shooting into a half inch.
I haven't tried them with a rifle yet, only with a bow and that hasn't worked out yet. Close but just not quite close enough. In my limited experiance with antelope and a bow it's not all that hard to get within 200 yards. That was the easy part. Getting them inside 50 has been the hard part.[&:]
Good luck!!!