I recently got the stamp for my SBR. I want to run the most efficient ammo through it. I have been researching for months, but it is hard to find velocity data from a 10.5" barrel. So, I ran a few rounds through a chrono. I wanted to find an open tip, non-barrier blind ammo for home defense. I want one with a velocity over 2300 FPS. Edit: Other criteria were figured out months ago. This is not a scientific test. I only ran ammo that is NOT barrier blind. I might run some barrier blind later. I ran some XM193 and AE223 55fmj to give me a reference that I am familiar with. I sighted in at 100 yards with the Federal XM193 and ran 2-5 shot groups of AE223J for a confirmation of sorts. Then I ran 2-5 shot groups at 100 yards of all I had. Edit: A small sample size. As I said this is not a scientific test. I ran it to record the data. I figured I would share it. It was no surprise the Black Hills MK262 and the Hornady TAP 75gr T2 retained most of their published velocities. The MK262 had better groups. The best groups were from the Hornady Steel Match, but all ammo had acceptable groups. The PPU performed very well. Considering the low price, this is a serious contender. The Hornady Match 75gr BTHP and the Fiocchi 77gr SMK had velocities below the 2300 fps requirement, so I stopped with one 5 shot group. Weather: Sunny to partly cloudy 80 degrees 60-80% humidity Breeze. 5-10 mph, at my back Set up: 10.5" FN chrome lined barrel, 1:7 twist, 5.56 NATO chamber CMT-TAC upper/lower Young Mfg BCG YHM QD Brake ALG Defense QMS with yellow JP Springs. Breaks at 4.5lb. Spikes ST-T2 buffer Nikon P223 4-12x40 BDC 600 Pro Chrono at 10 feet I am to lazy to post all the pics of the groups, but you can see the 5 shot groups in this photobucket album: Pics of groups Some of the groups shot very low. Sometime during the TAP groups, I must have moved the zero. I re-zero'd between the PPU groups. edit: Corrected XM193 BC.