In my Disc I've been shooting T/C (Hornady) XTP's 250 grain with a Knight Black Sabot.Pushing it with two 50grain Pyrodex pellets. I've gotten good results .I've shot two deer with is combo. One dropped in his tracks. The other went maybe 30 feet.I personally see no need in using the 150 grain max charge.Lowering your powder charge may do the trick for you.I agree with Mark Whiz.Try a different combination of pellets sizes.They come in 30 and 50 grain.You should be able to find the right load mixing and matching pellet sizes.
Ruger Redhawk