- Barnes Expander Muzzleloading Bullets 50 Caliber Sabot with 45 Caliber 250 Grain Hollow Point Flat Base Lead-Free Box of 24 at http://www.midwayusa.com/product/422084/barnes-expander-muzzleloading-bullets-50-caliber-sabot-with-45-caliber-250-grain-hollow-point-flat-base-lead-free-box-of-24 and
Hunting Gear Black Powder Hunting Muzzleloading Bullets Barnes Expander Muzzleloading Bullets 50 Caliber Sabot with 45 Caliber 300 Grain Hollow Point Flat Base Lead-Free Box of 24 at http://www.midwayusa.com/product/211841/barnes-expander-muzzleloading-bullets-50-caliber-sabot-with-45-caliber-300-grain-hollow-point-flat-base-lead-free-box-of-24.
I don't know if these are .452 diameter or not, nor if they are suitable for reloading for the 450 BM, but any of you who do know may be interested.