"Built using the real HK specifications with modern tooling, the Military Armament Corporation MAC-5 Semi-Auto Pistol is as close to a real MP5 as you can get and for substantially less than the real thing. It's authentic right down to the roller-delayed blowback action, which uses rollers to delay the rearward motion of the bolt, helping to spread out recoil impulse and delivering a smoother shooting experience. Like the original MP5, the MAC-5 functions with a wide range of ammo without the need for adjustment, and runs cleaner than other actions, allowing for extended use without frequent cleaning. Even better, the MAC-5 is compatible with a wide range of MP5 and SP5 aftermarket parts, and features a paddle-style mag release, fluted chamber, and machined tri-lug suppressor mount. It comes with a drum aperture rear sight and hooded post front sight, and is HK claw-mount compatible. 1/2""-28 threads. Package includes 2 mags, sling, flash hider, and hard case. Mfrs. 1-year warranty. Built using genuine HK MP5 specifications Roller-delayed blowback action Compatible with a wide range of MP5 and SP5 aftermarket parts Paddle-style mag release Fluted chamber 1/2""-28 barrel Drum aperture rear sight and hooded post front sight HK claw-mount compatible"