Finally got out to do some testing with the Ar-15. The front tube is not a free floater so I have to shoot sans sling, bipod or rest other wise the groups go crazy. This was prone at 50yds, 5 shots, numbered for your convience. Sorry for the extraneous boolit holes, Jen missed the part where I asked 'Please don't shoot the lower row of bulls'.
The .30cal hole at 12 o'clock was from scope sighting on the center sighting bull, not the 5rd group.
This was a lee HBC sized .308 weighing 195 grains with check and lube. Load was 15grs of H 110 in LC brass trimmed 1.350 inches, est. velocity of 1500-ish F.P.S. I estimate the group at 1.5" center distance between #5 and #1.