Unless things are really outta whack you're Blackhawk should be capable of 1" 25 yard groups (the gun that is, maybe not me, maybe not you) but that's easier said then done. IME handguns are much touchier to loads than rifles. While I can throw about any load together for a rifle and groups may double best vs. worst (say best load is MOA than worse load may be 2 moa) but with my handguns best may be 1" at 25 yards, worst may be 6" at 25 yards. My Rugers love XTP's but will scoff at lesser JHP's, my .357 loves BlueDot but hates 2400, my .32H&R loves commercial hardcast lead but the .357 leads severely with them, etc etc. Heck, even bullet design makes a big difference. My .357 throws groups that resemble shotgun patterns with Berry's 158gr HP plated bullets but shoots Berry's 158gr FP plated bullets reasonably well. Same manufacture, same weight, same plating, same powder load, completely different results.
If I were in your place I'd get some 158gr XTP's, some BlueDot, Unique and 2400 and work up 3 or 4 different loads using each powder and test em. Some fast, some slow, some maybe even below starting grains by the the book. If you're wanting a hunting load pick up some 180gr XTP's while you're at it(my Security Six loves them with 9.5grs BlueDot). But if after trying those bullets with those powders your groups don't shrink the problem probably lies elsewhere.
Note: Your crimp can make a big difference. I always thought Unique was a dirty powder until I started giving my loads a fairly heavy crimp and now no smoke, not much if any residue on my gun and better accuracy.