Regarding .223, you should know that Federal cases have been proven to have significantly thinner and weaker design than that of LC, PMC, Remington, and Winchester. I have seen the cases cut in half and compared, and have tested them myself with water volume. In a bolt gun, it may have no significance, but in a semi-auto such as an AR, cases will become unusable much more quickly, and some may cause dangerous situations.
Favor the X.
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