I' m not sure what the three round burst rifles will do today but in the late sixties we aimed for crotch and pulled the trigger. Normally the last round would be quite near the left collar bone or left shoulder. The purpose was to wound low with the first round or kill with the second round or wound with the third. Naturally sometimes the first round hit the dirt and the other two would ding ' em. Sorry I can' t tell you we had good groups back then, but it seems that Marines are always in a hurry. Except when they' re waiting...to be in a hurry.
Good luck with your question. I' ll keep checking this post...I' m curious too.

I sure would like to see a picture of a 1" , 3 round group fired from a fully automatic rifle, at 50yds. Yup, yup.

critch