Heckler & Koch HK4
A H&K HK4 with various magazines and an instruction manual
|Place of origin||West Germany|
|Used by||See Users|
|Manufacturer||Heckler & Koch, MAS|
|Weight||480 g (17 oz)|
|Length||157 mm (6.2 in)|
|Barrel length||85 mm (3.3 in)|
|Width||32 mm (1.3 in)|
|Height||110 mm (4.3 in)|
|Cartridge||.22 Long Rifle
|Action||Straight blowback, unlocked breech|
|Muzzle velocity||356 m/s (MAG-95, MAG-98, MAG-98c)|
|Effective firing range||Sights ranged for 25 m|
|Feed system||7, 8-round box magazine|
|Sights||Fixed, front post and rear notch, sight radius 121 mmm|
The HK 4 pocket pistol was first introduced by Heckler & Koch in 1967 making it the first pistol produced by the company. Mass production of this pistol started in 1968 and continued until 1984, with a final production total of roughly 38,000. Serial numbers 10001 to 36550 were for commercial distribution. German police and other government agencies received 12,000 pistols in the .32 ACP caliber with the designation P11 and were serial numbered 40001 to 52400.
It is thought that the basic design of the HK 4 is based on that of the Mauser HSc. The HK 4 was designated "4" because the pistol could be converted to fire four calibers. The frame and slide could accommodate three different centerfire calibers by simply replacing the barrel and return spring assembly and inserting the proper magazine for the caliber of choice. The fourth caliber, .22 Long Rifle (.22 LR), in addition to changing the barrel and magazine requires moving the extractor and firing pin to conform to the proper configuration for rimfire operation. The three centerfire calibers that the pistol can use are .25 ACP, .32 ACP and .380 ACP. Most standalone pistols were sold in .380 ACP and .32 ACP. All four calibers came as a two-box set with the extra barrels, magazines, screwdriver and cleaning kit.
The HK 4 is a straight blowback, double-action, single-action pistol. With a round in the chamber, a bullet may be fired by either pulling the trigger or by cocking the hammer and then pulling the trigger. The pistol automatically cocks the hammer after a round is fired. The safety incorporates a decocking mechanism that can safely decock the pistol with a round in the chamber. The hammer is decocked by putting the safety in the "safe" position and pulling the trigger, which allows the hammer to fall without striking the firing pin. When using centerfire cartridges, there is a red marking on the top of the extractor that serves as a loaded chamber indicator. This feature has continued in current H&K pistols. In the .22 LR configuration, the extractor remains extended and always shows the red marking on top. This means that when the pistol is in the .22 LR configuration, the extractor always indicates "chamber loaded", even when the chamber is empty. The pistol incorporates a plastic buffer in the frame. The buffer, which is loosely installed in the frame, can be lost during cleaning or can wear out and needs to be replaced periodically.
The pistol is disassembled by removing the magazine, cocking the hammer and putting the safety in the "safe" position. A notch inside the front of the trigger guard at the frame must slide down and be held in position while moving the slide slightly forward and then up to detach it from the frame, after which the barrel can be removed.
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