My Omega will shoot a range of loads but the Shock Waves[250 and 300grI like the 250 best]are made for the gun and do the best in mine and a lot of others it will shoot 100 to 130 gr and get 1 to 1.75 inch groups [5 shot] depending on which load and how well I am holding. It will shoot RS pyrodex, APP FF and777 FF[but I get crud ring from 777 and dont like to have to scrub it out before reloading when I am hunting] theXTP 250gr will shoot good out to 125 and they are cheapI used win. 777 209's for the777 and regular WIN. 209 for RS and APP FF.
I tried Power Belts but they would shoot good sometimes and not so good sometimes,of course they are designed for a CVA barrel which might have something to do with it. I have also tried some 240 and 250 lead bullets in .44 &.45 cal. and they shot quite good with 100 gr of RS. Hope this helps. Lee