The argument that it isn't "loaded" until a projectile has been inserted through the muzzle is what will be made here.Missouri law says ONLY loaded through the muzzle.
Any rifle capable of being loaded by any means other than the muzzle
You could load 45/70 rifle the exact same way. It would not be legal unless it was a pistol. Not that i care anyway. Mine shoot far faster and far cheaper for much less cost per shot. If you enjoy paying $2.70 per shot for 2000ish fps....Enjoy.