The HK4: H&K's First Pistol (Four Calibers, One Gun)
The Heckler & Koch HK4 is H&K's first pistol, notable for its ability to convert between four calibers: .380 ACP, .32 ACP, .25 ACP, and .22 LR. Designed in the mid-1960s and produced until the mid-1980s, approximately 40,000 units were made. The video details the technical process for converting between centerfire and rimfire cartridges, highlighting its similarities to the Mauser HSc.









