The HK MR556A1 for sale at Omaha Outdoors is the closest you’ll get to firing the rifle that killed Osama bin Laden without going to BUD/S and becoming a SEAL. The civilian legal variant of the HK416 in use by Navy SEALs, the MR556 rifle uses the H&K piston driven op-rod system instead of the gas tube of the standard M16/M4 platform. This rifle is instantly recognizable due to its higher upper receiver Picatinny rail and the distinct Heckler and Koch markings on the lower receiver. Also available is the MR556A1 Competition, chambered in 5.56 NATO / .223 Remington just like the standard MR556A1, which features a longer handguard and a compensator designed by OSS (Operator Suppressor Systems). Both rifles feature HK cold hammer forged barrels, the HK piston system, and free floating modular rail systems. A distant relative of the MR556A1 and HK416 is in service with the USMC as the IAR, an infantry automatic rifle meant to supplant the M249 SAW as an automatic weapon at the squad level.