Overview of the HK P11

Designed in the 1970s, the HK P11 manufactured by Germany’s Heckler & Koch is an underwater firearm which fires 3.9 inch steel darts.  Each of the five barrels on the weapon can load a single dart.  Once all five have been discharged, the unit’s barrel must be returned to the manufacturer to be reloaded.


Time almost stands still in the Firearms and Ordnance Gallery at the Armed Forces History Museum.  Authentic weapons from around the world, spanning many eras, can be witnessed in this extensive display.   A Revolutionary War bayonet - is the oldest, rarest piece in this gallery.


The charge for the HK P11 pistol is located in the pistol grip where it is electrically ignited from a battery pack.  The barrels are shielded from salt water by thin diaphragms, which become destroyed as each round is fired.  The effective range on this weapon is dependent on water depth.  If shot above the water, the range is listed at approximately 30 meters, or just shy of 100 feet.  Since the barrels are not rifled, they do not stabilize in the air making any target hit beyond 30 meters almost impossible.  When fired just below the surface, the distance average is about half of the above water range. 


Countries Using the HK P11

Heckler & Koch’s HK P11 is used by Navy combat divers in Denmark, Germany, Italy, Israel, France, the Netherlands, Norway, the United Kingdom and the United States.  Though bulkier than its Soviet counterpart – SPP-1M, the HK P11 is equipped with an additional chamber. 


Specification for the Heckler & Koch P11

  • Type:  Underwater pistol
  • Produced:  1976
  • Weight: 
    • 42 ounces loaded
    • Battery pack - 25 ounces
    • Length:  7.9 inches
    • Width:  2.4 inches
    • Cartridge: 
      • 3.9 inches in length 
      • Fires mini solid-fueled rockets with fins
      • Caliber:  7.62mm x 36
      • Action:  Electric actuated
      • Effective Range: 
        • 98 feet airborne
        • 33 – 49 feet underwater


A unique feature of the HK P11 – Heckler & Koch underwater pistol is its firing system which makes this weapon virtually silent when fired above water, a feature beneficial when coming ashore.