I had a Max, but not a Wesson, mine was a Handi. 19.1gr 4227 shot really well for me with the 140XPB and an even 20 with 158XTPs. 4427 was the only powder I ever really messed with in it much. It shot good enough I didn't feel the need to fiddle around with anything else.
That's one of the few guns I've ever regretted getting rid of.