I do not have a conversion cylinder for a black powder gun. I would definitely use only lead or cast bullets and keep the pressures LOW. I think that 6.0 grains of Unique under a 250 grain bullet should be safe. It would give you some where around 600 fps out of a 7 1/2" barrel. Do not use jacketed bullets, it takes too much pressure to get them reliably down the barrel. 9.0 grains will push it up to around 875 fps, but that may be pushing it a little. This data is out of Lyman's reloading book. Speer has Cowboy action loads - 230 grain lead bullet and 7.8 grains of Unique will get you 800 fps out of 5.5" barrel. That is a starting load. I would not go over that in an old Remington design. Speer does not list Blue Dot at all for their loads, so I would stay away from it. Bullseye is another possibility - use 5.0 grains under a 230 grain bullet for 700 fps in a 5.5" barrel. These are starting loads in the Speer 14th manual. You can always shoot black powder in these too with a lead bullet of course. Good Luck and good shooting.
