** When you buy products through the links on our site, we may earn a commission that supports NRA's mission to protect, preserve and defend the Second Amendment. ** The purchase of a good AR-15 is a ...

The MR556A1 Upper Receiver Kit allows high quality AR-style rifles to be retrofitted to HK's famous pusher rod operating system. An MR556A1 Upper Receiver Kit includes a complete barrel assembly, HK ...

The modular design of the AR rifle is a big part of its enormous popularity. By simply popping the takedown pins and switching the upper receiver assembly an AR owner can switch from a .22 long rifle ...