Most, but not all H&A "Minuteman" rifles were .45 caliber. I did see one that was .50 but that one had a "Numrich" barrel rather than the H&A marked one, so I assume it was made from parts at the end of the run. Hopkins & Allen muzzle loading rifles were assembled from parts left over and sold to the Numrich (Gunparts Corp) people in the late 80s and early 90s.They were serviceable muzzleloaders if on the "cheap" side. Most of the flintlocks needed serious work to spark reliably. Their breech plugs were allen-wrench screws, but worked just fine. These are not historically correct but a good, solid, inexpensive introductory rifle into the world of muzzle loading.