I've got a 2nd model .455 and have been loading for it. Out of my gun, the Fiochi load makes 630 fps. The Hornady ammo makes 575 fps. Using the Remington .45 Colt bullet loaded with 4.5 gr of Unique oal 1.115, I get 680 fps. With 5.2 gr of Unique, I get 785 fps. Using a hard cast 250 LFP and 3.4 gr of Bullseye, I get 575 fps. I use Hornady brass only and Winchester large rifle primers. Dean