The HK4. This pistol was the first attempt by HK to produce a handgun in their fledgling company. The gun was first conceived and designed in 1964, with the last units produced in 1984 . It was called the HK'4' because the gun is available in '4' calibers, and convertible to each.
Company founder Alex Seidel and the legendary Tilo Möller are the design engineers for this firearm. Möller was the primary design engineer on the MP5. The gun is based on the Mauser HsC pistol, which Seidel had considerable design influence on. It clearly shows the Mauser influence on the young engineers, who were employees of the great German gunmaker during World War II.
Total production for the civilian market was 26,550 units, serial numbered from 10001 to 36550. There were another 12,400 produced for the police, serial numbered 40001 to 52400. Total production for Harrington & Richardson American imports was 8,700, serial numbered 001-8700.