Your Right!! the box of 50 Hornady 300 grain XTPMAG are listed as a magnum what ever the difference is I have no idea. The Hornady .45 caliber 300 grain SST/ML I am guessing are made for muzzleloader? Make sense? I am using the black high pressure Harvester Sabots. They are made for a .452 diam projectile, so this should be a good set up. I will be interested in what you find out. I know what you mean about not wanting to shoot off the Silver Lightening all at one time. I forget what they costed now with shipping, but this is not something you would go and blow through paper for fun everyday. Could get a little expensive.