"The latest variant of the world-famous HK416, the HK MR556-A4 Carbine Semi-Auto Rifle is the premium-grade commercial variant of its select-fire military cousin. The MR556-A4 Carbine utilizes HK's gas-piston operating system that virtually eliminates malfunctions commonly found in direct-impingement gas systems and yields much cooler, cleaner, lower-maintenance operation. This is the same key feature critical to the success of the HK416 used by elite military and law enforcement personnel worldwide. The MR556-A4 Carbine functions reliably and accurately under the most extreme conditions with a wider range of 5.56 NATO and .223 Remington ammo than any other commercial AR-platform rifle. And its adjustable gas regulator allows the operator to tune the action for suppressed and unsuppressed operation. The A4 enhances the performance by adding ambidextrous controls, reducing weight, and creating a slimmer profile. The MR556-A4 features the slim 6-position stock and a lightweight, slimline M-LOK handguard. 16.5"" match-grade, cold hammer-forged barrel. Updated angled magazine well for reliable feeding from all AR-pattern magazines. Includes 1 magazine. HK short-stroke gas-piston operating system 16.5"" match-grade, cold hammer-forged barrel Lightweight, slimline M-LOK handguard HK416 slim 6-position stock Ambidextrous safety selector, mag release and bolt release Adjustable gas regulator for running suppressed and unsuppressed Angled mag well for reliable feeding from all AR-pattern mags"