I shoot 250gr shockwaves with 130gr pyrodex RS (ffg equivalent) in my Omega. Easily keeps them inside 1.5". But if I were starting out from scratch, I'd shoot 2 shot groups on a cold bbl, going up in 10 grain increments starting with at least 90gr ('modern' bullet--need a little more speed to open up). You should find a charge that's a little better than the others.

The do-all charge for me seems to be 120gr Pyrodex RS. I've used it in 3 different rifles, including 2 omegas and 1 remington genesis, with the 250gr shockwave and they all shot well at that level.