The PSP Polizei Selbstlade Pistole (Police Self-Loading Pistol) The First P7 Cal. 9mm x 19
The P7 series history is difficult to describe, given that the most detailed history that I have of it comes from a book written in German. What is plain from what I can translate, is that the genesis of the P7 series comes from a squeeze cocking design by a Chicago based gun designer named Allan W. Woodruff in 1918! The patent drawings are the first photos below. Helmut Weldle, now retired after a long career at HK, headed the design team for the PSP, or Polizei Selbstlade Pistole. It was the first P7, so to speak, and was the basis for all subsequent design changes made to the more familiar P7 models to follow.
Prior to the design of the readily recognizable P7, the squeeze cocking design was tried on other pistols, the HK4, and a Colt 1911. HK4, serial number 9999, (the first production HK4 had a serial number of 10000), was tapped to adapt the squeeze cocking design, albeit from the rear of the grip rather than the front.
Patent number 1,284,020 dated November 5, 1918 for Allan Woodruff's squeeze cocking design.
HK4 with experimental squeeze cocking mechanism built into rear of frame.
After adapting the prototype mechanism to the HK4, Weldle's team tried a similar adaptation to a Colt 1911 variant, in 1971.
The now recognizable front squeeze cocking design was again tried on another HK4, serial number VM 058 (Versuchsmodelle or test model) and it was becoming apparent that the design was nearing finalization. Patent 26 27 641 was close to becoming reality.
HK4, serial nmber VM 058, with front squeeze cocker, circa 1976.
PSP Patent number 26 27 641 showing the now recognizable design perfected by Weldle and his team of talented engineers.
Visible in the patent design above is the other salient feature of the PSP design, the gas retardation system. Once again, firearms designers rarely start from scratch when implementing new designs, and the gas system was no exception. The roots of the PSP gas design date to 1927 and Belgian gun designer John Destree. His gas piston design is shown below.
1927 gas retardation system design of Belgian John Destree.
Polizei Selbstlade Pistole Serial number 001
The PSP was produced from May of 1976 through 1978. Only 239 total models were manufactured. The serial numbers for the PSP go from 001-239, then 240-250 are for the PSP/P7, and after 251 starts the P7 series.