HK 81000018 HK45 Compact *MA Compliant 45 ACP 3.94" 8+1 Black Black Polymer. The HK45 Compact is well-suited for personal defense use, and it has a DA/SA trigger system with a safety/decocking lever on the left side. The HK45C features a "slim-line" grip, shorter barrel and slide than the standard HK45, but it is otherwise functionally identical to the standard HK45. The HK45C can be fitted with a threaded barrel for use with a muzzle-mounted sound suppressor. The internal mechanical recoil reduction system reduces the recoil forces imparted to the weapon and shooter by as much as 30%, improving shooter control during rapid firing and increasing component service life. This pistol features a MIL-STD 1913 Picatinny rail, ambidextrous controls with dual slide releases, enlarged magazine release, low profile drift-adjustable 3-dot sights, polygonal rifling for longer barrel life and increased accuracy, and two magazines.