Umarex H&K HK45 GBB.

The HK45 is the largest-caliber pistol made by Heckler & Koch (.45 ACP). This licensed airsoft version comes with a polymer frame and metal slide. The blowback effect is appreciable (approx. 1 joule muzzle energy).

Features: 

• Caliber: 6mm BB
• Power: Source Gas
• Magazine: 24shots 
• Trigger: Single Shot 
• Energy: <1Joule 
• Hopup: Adjustable 
• Length: 205mm
• Weight: 878g