I built and shot one for a number of years; 45cal, worked great. I used a breech plug which used cut down 308Win cases. My state changed regs and I could use a rifle so I did. The barrel and plug are available for sale, PM me if interested.
I can't remember load data offhand; I used 200gr Shockwave bullets pushed fast enough that I didn't dare shoot a deer closer than 100 yards. Past that it was a great killer, my average shots were 150-250 yards. Longest was around 400.