The Soviet Union began developing underwater guns nearly 50 years ago. The idea — to arm commando frogmen and other combat divers for underwater engagements, however rare and unlikely these subsurface firefights might actually be.
In the late 1960s, Moscow enlisted “TsNIITochMash” — the Central Scientific Research Institute of Precise Mechanical Engineering, a Soviet design bureau — to work on an underwater handgun.
“Underwater, conventional bullets are highly ineffective, being inaccurate and limited to a very short range with a rapidly decreasing lethality,” Robert Segel explained in Small Arms Defense Journal. Traditional bullets basically lose all velocity and sink or fall apart almost immediately after hitting water.
An episode of the popular T.V. show MythBusters demonstrated how even the hefty 600-grain, full-metal-jacket bullets from a high-power .50-caliber sniper rifle can’t travel more than a few feet under water before they lost their copper casing, fall apart and sink.
In a more dramatic display, Norwegian stunt-physicists Andreas Wahl placed a loaded assault rifle on a tripod underwater in a swimming pool, rigged a stringer to the trigger, stood several feet in front of the rifle and then pulled the string. The gun fired, but the bullet drifted to the bottom of the pool before getting anywhere near Wahl.
A pesky detail like physics wasn’t going to stop the Soviets.
Under the direction of a young engineer named Vladimir Simonov, TsNIITochMash explored ways of maintaining a projectile’s velocity underwater. They eventually produced a gun they believed would solve the problem — the SPP-1.
The SPP-1 looks a little different than your typical handgun. It resembles an elongated Reliant or a Derringer. The SPP-1 has four smoothbore barrels in a square cluster hinged to the frame just in front of the trigger guard. The pistol breaks open for loading and unloading.
he biggest difference between the SPP-1 and other handguns is not how it looks but what it shoots. The SPP-1 fires 115-millimeter steel darts with slightly flattened tips that weigh roughly 13 grams each, according to Segel. Once a dart is discharged from the gun it is kept stabilized bycavitation, a bubble-like vapor cavity created around the dart as its flattened tip moves through the water. The cavitation results in reduced drag on the dart, as well as increased accuracy and lethality.
The Soviet navy adopted the SPP-1 in 1971 for frogmen and combat divers. The gun has since been upgraded, with few modifications, to the SPP-1M and was still in use by Russian navy special forces until 2011, at least.
Despite all of the research that went into the SPP-1 series, it’s still very limited. The effective range of the SPP-1M is roughly 17 meters at a depth of five meters. That range decreases precipitously as depth increases. The SPP-1M can be fired out of the water, but because it’s firing a dart through a smoothbore barrel the range and accuracy is greatly diminished in the open air. “In an emergency, at very close range, it is still highly effective,” Segel wrote about using the weapon out of water.
Not to be outdone by the Soviets, in the early 1970s the United States quickly began work on its own underwater handgun for Navy SEALs, resulting in the Mk 1 underwater revolver. It fires darts, as well — andalso looks kind of funny.
As War Is Boring‘s own Joseph Trevithick explained in a 2014 article, a detachable six-round cylindrical magazine feeds the Mk 1. Each dart in a magazine is contained within a watertight tube that also functions as a barrel. This self-contained design greatly reduces the level of sound created by the gun discharging, both underwater and on land. To reload the gun, the operator removes the entire magazine cylinder and replaces it with a new one.
The Mk 1 has an effective range of roughly nine meters at a depth of 18 meters, according to Trevithick. The gun can also be fired in open air, but with diminished range and accuracy comparable to the SPP-1M.
Around the same time the Soviets adopted the SPP-1, they directed TsNIITochMash to start developing an underwater assault rifle. Siminov again led the design efforts, eventually developing what came to be known as the APS.
The APS underwater assault rifle has a simple design with only 42 named parts, and looks similar to the AK-47. It fires 5.66-by-120-millimeter steel darts from a 26-round magazine, according to Chris Eger writing at Guns.com. It can fire up to 600 rounds per minute, underwater or in open air. However, like the SPP and Mk 1, the APS has a smoothbore barrel. It’s highly effective underwater but nearly useless above the surface.
The Soviet navy adopted the APS around 1975. The weapon also saw service in other Warsaw Pact countries, according to Eger.
Read the Remainder at War is Boring