I used 3 1/2 #2 1625fps they work great. But you need to practice they are fast. What I did was went trap shooting and loaded some trap loades that are around 1600-1650fps
1 1/8 # 6 lead powder was LONGSHOT and they are fast from 27 yards you do not need to lead the bird. With the fast steel they are fast but lose there speed quickly I find that I do not need to lead birds by much at all when pass shooting and never with there feet down. You need to find the right gun ammo and gear that fits you and stay with it good luck.