Interesting ammo issue, never saw this before. My uncle, whose only guns were ever bolt actions, muzzle-loaders, or shotguns for hunting, bought an AR-15 last year from Rural King during the Hillary-hype. The only ammo he tried in it was something I'd never heard of before - Geco .223 Remington 55gr (German-made, black & red box of 50, all rounds come on plastic 10-round stripper clips). None of the rounds would fire. He manually cycled the gun 10 times without success. None of the primers had dimples, suggesting that the firing pin wasn't striking them. He gave me the ammo and IMO their primers are less than perfectly level, appearing to be seated just a bit too deep. I haven't had a chance to test-fire any of it in my own guns, an AR-Frankenrifle in .223/5.56 and a Mini-14 in .223. I've asked but he hasn't yet told me if he's tried other ammo. Way I figure it, no dimples says that the firing pin isn't making contact, suggesting a BCG/firing pin issue, especially if this stuff runs okay in other guns. On the other hand, if it fails in multiple guns then it might be the ammo. What say you folks? Anyone know anything about this German Geco ammunition? [Update] Just heard back. The rifle is a Core-15 Scout Rifle in .223/5.56 and my uncle says he's since shot two other kinds of ammo successfully. Unless it's a bad batch it looks like maybe a finicky rifle that just doesn't like Geco.