When Doc White had the Jim Bridger Hawken at the Green River Rifle Works in 1975, he took it the the Fort Bridger Rendezvous and shot it, I don't know how much. It is about a .53 caliber. Another time it was taken out of the museum at Helena by the curator to a gun show, but sent back to Helena with two other guys. They said they'd take it back on the condition that they could shoot it. He probably thought they were kidding, they weren't. They stopped in a gunshop and got a few balls, .535's were all the guy had, and shot it 15 or 20 times. They wrote this up in Muzzleloader Magazine, I think it was, and I have that copy here somewhere. Title of the story was "The Day Old Gabe Smiled" if I remember right. How they got those .535 balls down that bore, must have taken some ramrodding, but they didn't mention that. Doc White also shot some original Hawkens when he was in Alaska.