Oh, boy, was the Cold War a wild time! Man, the early development of Special Operations forces led to some truly weird developments. SEALs and Spetznaz troopers, in particular, proved that a small team of seaborne commandos could be hell on Naval infrastructure. As such, these seaborne commandos would need specialized weaponry to fight like legitimate frogmen. This led to the development of the underwater firearm concept.
Underwater firearm? Are you serious?
As a heart attack. In the 1970s, there was a vision of teams of frogmen fighting each other underwater as if a Mack Bolan novel came to life. If it were to come true, normal firearms wouldn’t do the trick in frogmen firefights. So, militaries had to develop an underwater firearm, or at least come up with some underwater knife fighting techniques.
So they developed a few different variants of the underwater firearm idea, and I’ve gathered them here today. Plenty of ideas might have been patented, but I only include the underwater firearms that were developed and actually produced. Here are the five we know about. Who knows what others state governments have kept as a secret.
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Mk1 Underwater Defense Gun
The development of the first underwater firearm comes from the United States in the form of the Mk1 Underwater Defense Gun. The Mk1 entered service in 1970, and the Naval Special Warfare center desired to keep it as secret as possible. It became a sign-out-only weapon that required troops to do paperwork to take the weapon out of the armory.
The Mk1 utilized a pepperbox style design, and this means you have individual barrels that rotate and fire. The double-action trigger rotated the cylinder and fired the weapon. As an underwater firearm, the weapon couldn’t use standard ammunition. In place of your normal projectile, they used metal darts.
These 4.25-inch tungsten metal darts had four fins to ensure rotation and looked like a miniature arrow. The effective range of the weapon was only 10 meters, and the darts moved at about 730 feet per second.
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HK P11
The Mk1’s replacement came in 1976, and the German firm Heckler and Koch created it. The P11 offered NATO shooters from a variety of nations their first underwater firearm, despite being old hat for the United States by then. The P11 used a five-shot pepperbox design, and each barrel held a 7.62x36mm dart.
Each barrel is completely sealed, and when fired, the seal is broken. All five barrels form a cluster, and clusters can be reloaded by the factory or discarded entirely in combat. The 7.62x36mm darts featured a 15-meter effective range, which outperformed the older Mk1 by a full third.
The P11 used an electric firing system with a battery located in the pistol grip of the gun. It’s a truly fascinating weapon that might still be in service with NATO frogmen today.
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SPP-1
The SPP-1 came out of Russia and represented The Russian entry into the world of underwater firearms. This four-shot, pepperbox-style pistol fired a .18mm dart that was roughly 4.5 inches long. This big double action only pistol started its service in 1975 and apparently remains in service to this day.
The SPP-1 shows some Russian ingenuity, as the weapon is much less bulky than western variants of the underwater firearm. The SPP-1 launched darts at about 790 feet per second and had an effective range of 17 meters or so. The Russian pistol seems to outperform the Western models, but it’s tough to say since the ballistic measurements are tough to calculate underwater, and Moscow’s reputation for offering up legitimate performance data on their weapons isn’t particularly good.
Does the larger dart size of the Western P11 outperform the smaller dart of the SPP-1? Tough to say without some serious testing underwater.
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APS Amphibious Rifle
The Russians didn’t stop with the SPP-1. They also wanted an underwater rifle, and the man who designed the SPP-1 would go on to design the APS Amphibious rifle as well. The APS offered a rifle-sized platform, but it’s technically not a rifle, since the barrel isn’t rifled. I guess the term long gun probably describes it best.
Regardless of nomenclature, the APS Amphibious rifle offered an effective range of 30 meters. That’s a fair bit more than the pistols offered by on either side of the Iron Curtain. Plus, the weapon used a specialized magazine that allowed the APS to hold 26 rounds of the special underwater projectiles.
The weapon fired a 5.66mm steel dart and could fire in fully automatic. The downside to a rifle like this, however, comes from its size. Its bigger, heavier design makes it harder to maneuver underwater, especially with its large and awkward magazine.
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ADS Amphibious Rifle
The ADS Amphibious rifle is the evolution of the APS. Unlike the APS, the ADS actaully is a rifle, as it utilizes a rifled bore. The ADS came to be because the APS worked well underwater, but sucked above the surface. The options were to carry two guns (and that must’ve been a pain when dealing when swimming, dealing with all your scuba gear, and fighting) or to create a new platform that could function in either medium.
The ADS promised to do both very simply, with users having to simply swap magazines as they went from above the surface to below or vice versa. Below water, the ADS used a 5.45x39mm PSP round. Above water, the weapon uses standard 5.45x39mm ammunition. The range underwater was roughly 25 meters and the weapon offered select-fire operation.
The ADS Amphibious rifle uses a bullpup design. This mitigates length and size and makes the weapon easier to use underwater, and those benefits translate well above water as well. The ADS came to be in 2013 and shows that the Russians remained very concerned with frogmen firefights right into the 21st century.
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The threat of the Underwater Firearm
The underwater firearm doesn’t necessarily kill by penetrating deeply into a guy’s chest. Sure it can, but it seems like the real advantage in frogmen firefights would be targeting gear. Ripping apart masks, breathing tubes and harnesses, protective wetsuits, helmets, and targeting the thin, often plastic windows of mini-subs are all ways these weapons could render swimmers combat ineffective with quickness and ease.
Has one of these frogmen firefights ever actually happened? If so, it’s not documented or discussed freely. However, the idea fascinates me. An underwater firearm seems a little silly these days, but they’ve clearly stuck around for quite some time, and that means the nations that operate these platforms must see a good reason.