I recently purchased a S&W AR 15 rifle and took it out for the first time today. Before I shot it I cleaned it and lubed it up. But anyways the problem I am having is that the gun is not firing the second round. It fires the first, ejects it, chambers the second and then click... nothing. I first thought that I had a miss fire so I waited and then checked. And the round had a very tiny pin mark on it from the firing pin. So I set the round far away and then proceeded and it happend again and again. I even tried different ammo and different magazines. So just wondering if anybody had any thoughts.