Brief history on the subject Ruger Blackhawk Bisley 45 Colt. After obtaining this Ruger I picked up some Winchester cowboy action loads with the 255 grain boolit and did some shooting with it. Accuracy wasn't bad but it wasn't great. Next thing I tried was some RCBS 270 SAA boolits. Results were terrible. Tried boolits from 10 bhn to 22 bhn. Velocities from mild to wild. Still would get shotgun patterns for groups. Now I had already done some measuring of the throats but at the time I did not have any pin gauges. Getting frustrated the gun was put away for another day. Selling was not an option because of who I purchused the gun from. He was family and we had recently lost him to cancer. I learned alot from you people here and alot of times I read something that would remind me of that Bisley. I decided I would order some minus pin gauges. After reading fermin's article on firelapping I decided I would go that route with this gun. Pin gauges showed the throats measure .455 and the muzzle accepted a .443 gauge but it would not trave the length of the barrel without sticking. First restriction was just behind the front sight. A .442 gauge would freely pass through the full length of the barrel. I loaded up 30 rounds of lapping boolits after getting the compound from Beartooth. I used my own cast boolits. I had firelapped a RSRH years ago with Veral's compound and boolits so I had some experience going in. I ended up shooting all 30 rounds through the gun and was cleaning the gun every 12 rounds. I was amazed when I saw the lapping rounds start grouping just like Fermin said. After the 30 rounds and a very good cleaning I rechecked the bore. Much better but felt like it needed just a little more work. I loaded six more rounds and fired them and repeated the cleaning process. Now knowing I was going to do this and needed some boolits sized to fit the throats I turned to BRP and talked to Bruce about needing some boolits that could be sized at .455 for this gun and what were my options with his molds. I had an order in with him at the time for the 462-420 GC and he told me he would check and get back with me. He did so and sent me a supply of his 454424 which were cast at 50/50 and air cooled. I sized them with a .455 sizer ( Buckshot ) and used a lube recipe sent to me by another member here. I really wanted to try some HS6 but did not have any and could not find any locally so I ended up loading 9.0 grains of Unique and used a WLP primer. I did not chrono any loads as I was only concerned with the accuracy. I was simply amazed when the first six rounds were fired and I saw the group. The first 2 shots flew high but centered and the last 4 where all in a little cluster. I shot 12 more rounds at the same target and with a some shots that I pulled off the group there were 13 rounds that measured 2.862" measured from outside to outside. Distance was 20 yards fired offhand. I was so amazed that I shot everything before I realized it. I would have liked to see what it would do from longer range. But with the past performance of this gun I am really pleased with these results. Now the only thing is to order another mold and get back to shooting. I should also report there was zero leading in the bore and there was some lube on the muzzle.