I have had good results with both the Lee 356-124-RN-TL and the Lee 356-120-TC over 4.0 grains of W231/HP38 in my M&P. At 10 yards offhand, it's fairly easy to get 5 touching shots on paper.
I recently bought a pound or two of AA#2, because I can get it for about $20/lb here, compared to $27/lb for 231/HP38. I really, really wanted to like this powder. It meters way better, requires smaller loads in addition to being less expensive, and supposedly isn't position sensitive, so therefore theoretically better for light target loads.
But I can't get it to shoot. Accurate's published load data for a 124gr lead bullet go from 3.0 to 3.8 grains. My Lee 120gr mold gives me almost exactly 125 grains after powdercoating. I shot groups with 3.2, 3.4, 3.6, 3.8, and 4.0 grains yesterday with AA#2 (COAL 1.066"), and couldn't get it to group for crap. Shots all over the place, but no pressure signs in the primers or excessive recoil. The same trip I tried several loads of HP38 under the same bullet, and they all shot better than any of the AA#2, with the best being 4.0 grains, unsurprisingly.
I guess it comes down to just some guns like some powders and dislike others. Just bothers me that I don't know why. I'll probably resign myself to paying for the slightly more expensive HP38 going forward, unless anyone has a pet load with AA#2 and a 125ish grain bullet that makes minor power factor for USPSA shooting