The HK4: H&K's First Pistol (Four Calibers, One Gun)
This guide details the process of converting the Heckler & Koch HK4 pistol between its supported calibers, including the critical step of flipping the breech face for rimfire ammunition. The video highlights the HK4's unique design, allowing for .380 ACP, .32 ACP, .25 ACP, and .22 LR. Expert instruction is provided on the technical conversion process.










