When using smokeless powder in the Savage MLII, does the higher pressure eliminate some of your choices in projectiles? (for example will it destroy sabots, or blow the skirts off of conicals or powerbelts?)

yep, No conicals, period. Only certain sabots, too. The smokeless needs a tight fit on the sabot or it will not fire. Some sabots will just blow by if they are not constructed tuff enough. There are sights devoted just to Savage muzzleloaders.