Im assuming your best target group and your best number group is the same(55.5). If so I would not worry about the other charges and built around that. Go up and down .1 or .2 grains and then play with the bullet seating. Do not change more than one thing at the time. If you are shooting in the same location keep an eye on the temperature and wind. Also, do not leave a shell in the chamber or even the magazine when you are waiting for the barrel to cool. You will get crazy results that way, dont ask me how I know... Definitely shoot at more than 100 yds. That group is too tight at a 100 to tell much about improvement. Of course, you might know or planed on all of this already in which case just ignore me...