I'm not sure if I'm looking at this the way you are asking(GMMAT) but I know from practice that at 45yrds. I will have a group about 2''.
Not from the spot, per see , but a 2" group w/ maybe a flyer in there sometimes. 2-3 in.'s is what I consider my margin for error. In a hunting situation I would never shoot 45yrds. To allow for the variables that could occur I keet my shots under 35yrds. Unless the aminal does a tail spin when I release I know it will produce a kill shot even if I've misjudged the yardage by 3 or 4 yrds. We all know bow speed will have a slight affect on this variable , but that comes w/ knowing your equipment.