The rifle barrel was made for a "sabot" and round ball. Please note , sabots were not even made for pistol/rifle bullets when I was given this rifle. I am sure that it would shoot just fine with a minni or modern sabot and 45 cal bullets. This is the only safe queen I have ever owned. It has never been fired. And I have owned and used several Mowrey rifles in the past. But there is something special ( to me ) about this rifle.