I use semolina in most of my revolvers and single shot pistols and have done trials for accuracy (rested guns) and velocity. Using semolina the velocity drops a few fps (20-30) but seems to become more consistent. When I'm shooting for real it doesn't seem to make a damn bit of difference to my scores.

I think the only reason I do it now is for the conversation it causes. A femail associate of mine uses curry powder as a filler just to see how many people ask who's cooking curry?