What SuperMan said. I’ve used 7.5 W231 for years with a cast 220 grain SWC (H&G #258, I think). Good accuracy. I don’t recall the exact velocity but I’m sure it’s around 900 FPS in my 4” guns.

(Edit) Well, to my surprise the chronograph data happened to be right infront of me. 972 FPS, ES 13 and 969 FPS, ES 31. Tested twice. 5-rounds each. Velocity was a bit higher than I remembered. Winchester brass, Federal primers.