I've shot a little over 150 rounds of it so far (the Dick's SG 150-rd 55gr value packs for $30 each - a little over 20 cents/rd after tax), and it performs exactly the same for me as the Winchester value packs from Wal-mart. I get about 1 MOA or better from my 20" 1/9 twist DPMS chrome-lined upper. Also works fine in my 16" CAR, but I haven't taken the time to shoot at paper with it yet to see how well it works - just cans and fun targets.
I have had no failures of any kind with this ammo (55-gr, 150-rd value packs). I recently bought another 300 rounds and have it loaded in mags ready to go.
Side note: I joined Dick's "Score Card" program, and I've almost got enough points to get a $10 gift certificate for more ammo.
Why is it that of the 9 people who have posted, all have great reports, only two have had even minor problems (dirty, slow complaint and a few failures to fire), but 8 people have voted that they had MAJOR problems with NO comments posted? Me thinks we have some trolls aboard this ship, mateys. ETA:
I just sighted in my new 3-12X Barska scope with Ultramax 55-gr FMJ rounds from a Dick's Sporting Goods 150-rd bulk pack. I achieve 2 MOA grouping (two inch diameter pattern with absolutely no "flyers" at 100 yards) consistently with 10 shots and better than 1 MOA (about a 1/2" group) with 3-shot patterns (usually three holes almost touching). I had previously thought this was the defacto method of finding out how precise your shooting was, then I read the stickied post about 10-shot groups.
I did this with my DPMS 20" chrome-lined barrel, lying prone, and using my Harris bipod. I have standard handguards (no free float), and a heavy, fluted barrel that was cryoaccurized by DPMS, by the way.
To see if it was better or worse than other brands, I bought two 20-rd boxes of Remington 55-gr FMJ .223 from Walmart ($5/20) and shot at a target placed beside my Ultramax bullet-riddled target. The point of impact was shifted 2 inches high and 2 inches to the left from the Ultramax zero, but it grouped almost exactly the same as the Ultramax (a little under 2 inches diameter pattern for 10 shots at 100 yards). I would have tried my WWB (Walmart Winchester white box value pack) ammo as well, but I am hoarding it until I can find more, and I'm down to 90 rounds.
Given that I can get 5 Ultramax rounds for the price of 4 Remington rounds (20 cents versus 25 cents per round), I am going to keep using the Ultramax that I get in 150-rd value packs. It's certainly not the highest quality ammo there is, but I have now run through about 300 rounds of it with zero problems and get better than decent accuracy from my rifle with it. Keeping all 10 shots in the 2" black square in my sight-in target at 100 yards and all 10 in one tight quarter-sized hole centered on the bulls-eye at 50 yards every time is about all I could ask for in precision with my non-precision build and my non-precise shooting method.
I've got to read more about sighting-in, though, to figure out why my zero point goes UP
about 2.5 inches from 50 to 100 yards. The 5.56mm trajectory is weird, to say the least.