Shoot multiple 10 shot groups. That will give you a better idea of where the center of your group is. 3 shot groups really tell you nothing. I was at the range yesterday testing some loads with my new to me rifle and some of the groups showed double grouping where the first 3 shots were in one ragged hole, then the next 2 were outside the group by 1/2"+. Getting all fancy and talking about spin drift and bragging about 1/4" groups, "if you do your part" really is a moot point, if you are not shooting more per string. Here's an interesting read for you:
The trouble with 3 shot groups
