The standard 223/556 AR15 magazine is extremely versatile and can accommodate several different calibers.  However, the most reliable, hassle-free operation is achieved in most cases by using a magazine designed specifically for the cartridge being fired. offers a selection of magazines for each caliber that we know from first-hand experience are well-made and will consistently feed ammunition without issues.  We always recommend using a magazine matched to the caliber of your upper/barrel. will not ship magazines that violate regulations in the jurisdiction of the shipping address entered at checkout.  You are responsible for knowing your local gun laws, but we are happy to help.   888.706.0633