Pretty amazing complete upper - Geissele Super Duty MOD1 5.56mm, 14.5 inch Upper Reciever

I got this is the .812 HBAR because I wanted to test out the accuracy of a heavy 556 system/barrel. On our first outing, this shot consistently sub 1" 5 shot groups at 100yds and even one group at 1.5" at the 200yd bench (I most likely got lucky). Below is the ammo we used and the rough group sizes @100yds. All groups were shot multiple times at 5 shots. We used a full 20rd box of ammo of each type to shoot 4 groups and we averaged the spread across the 4 groups. I have some 62gr and 70gr Barnes VOR-TX in bound and can't wait to see what those group like. So far, for the money, the 77gr and 75gr loads seem to be the most accurate at 100 and 200 yards, and weirdly this thing hates the expensive 69gr SMK loads from 2 different mfg.

AAC ammo
62gr Black - ~1.5" groups
69gr SMK - ~1.75" groups
75gr Black - ~ sub 1" groups
77gr OTM - ~sub 1" groups

Hornady
75gr Black Interlock HD sbr- ~sub 1" groups

Federal
55gr M193 - ~2" groups
69gr smk - ~1.75" groups