I have a preban Colt H-bar Sporter that is labeled 5.56 on the barrel but .223 on the lower. Which is it? I have looked around online and found that Colt makes only 5.56. I have also read that many manufacturers often mislabel their firearms in this case. The reason this comes up is because my gun refuses to shoot 5.56 rounds it repeatedly fires and ejects a round but fails to chamber the following round, in addition to this it also will pop primers making me think this chamber is in fact a .223. Does anyone know for sure which it may be? If it is a 5.56 why is this happening?