i tried a box of olympic 223 ammo in my AR-15 with the same problem. I just got sick of it and never touched it again. Luckly it was only 10 bucks for the ammo, but i'd never use that brand again. If i were you i might just try and sell it.
Remington UMC and Winchester USA ammo both work very good and are pretty darn accurate for a FMJ at budget price