Just about to start reloading .243 and 6.5x55 for deer stalking and occasional fox. Planning to use Hornady Interlock 100gn for the .243 and 140gn for the 6.5x55, both with Federal primers and brass. The problem is which powder!! Can I get away with using the same powder for both calibres or should I use 2 different ones? Rifles are Winchester M70 Sporter (.243 Win) with 1:10" twist, and CZ 550 American (6.5x55SE) with 1:9" twist. All advice/suggestions gratefully received!