How a H&K SL9SD Rifle Works

Wikipedia:
Type Semi-automatic rifle
Place of origin Germany
Service history
Used by German Army Reservists
Production history
Manufacturer Heckler & Koch
Produced 1998-present
Variants SL8, SL8-1, SL8-4, SL8-5, SL8-6, SL8-10, SL9SD, R8
Specifications
Mass 3.9 kg (8.6 lb) with magazine
Length 980 mm (39 in) with magazine
Barrel length 510 mm (20 in)
Height 250 mm (9.8 in) with magazine
Cartridge .223 Remington, 5.56×45mm NATO
Action Gas operated, short stroke piston, rotary locking bolt
Rate of fire Semi-automatic
Feed system 10-round single stack and 30-round double stack, detachable polymer box magazine
Sights Adjustable Iron sights and detachable MIL-STD-1913 rail. G36 sighting systems optional.