I have a 50cal CVA Optima Pro and have shot 2" groups at 100 yards with both the 270grain platinum and 245grain aero-tip Power-Belt bullets. I shot them both with 150grains of pyrodex pellets. According to the Power Belt website, both these bullets have the energy to take deer at 250 yards. Powerbelt Bullets
Although these bullets are not saboted, they do have a plastic cup on the bottom. Power Belt says you can shoot 6-7 rounds between cleaning. My experience is quite different, I quick-clean my gun after two shots. I tried shooting five rounds without cleaning and found that accuracy seriously deterioriated after the second round.