Not really-you are limited to belted magnum cases no longer than the .300 Win. Mag. Unless you alterred the action to accept longer cartridges.

As noted above, it is hard to improve upon the 7mm Mag.. But one cartridge I would consider is the .308 Norma. Granted, this round has been overlooked for a number of years, but it is probably the best .30-cal. belted round there is. Another possibility would be the .30 Newton, essentially the .308 Norma w/o a belt. I understand Jamison is getting ready to offer brassfor this round.