This odd looking suppressed revolver was specially modified from a Smith & Wesson handgun to play a very specific role. Unfortunately, flawed technology that wasn’t up to the rigors of military use ensured that it never got to fulfill its intended purpose.
The photo above was recently posted on Facebook by War History Online with only the description “Tunnel rat,” sparking a lot of speculation and confusion in the comments section.
One user finally posted a link to a thread on smith-wessonforum.com that shed some light on the odd-looking set up that was a little too ambitious for the technology of the day.
According to the post, the Smith & Wesson .38-caliber M&P Model 10 revolver was packaged in a kit along with the headlamp and the gunbelt the solider is wearing and it was, indeed, intended for use by soldiers who explored enemy tunnels, or tunnel rats, as they were known in Vietnam.
The kit in the photo is an example of a “Tunnel Exploration Kit” produced for the military in 1966. It had become apparent that to fight the Viet Cong on their home turf, it would be necessary to pursue them into the intricate network of underground tunnels and bunkers they had constructed as bases, transportation and escape routes, storage spaces, and even hospitals. This meant U.S. soldiers would have to go in through narrow openings to flush the enemy out, requiring special gear.
From the declassified Department of Defense report on the Tunnel Exploration Kit, “During a visit to the 1st Infantry Division a need was indicated for accessories to be used in tunnel exploration. Large complexes of tunnels from 100 to 400 meters in length and varying in width and height require exploration normally from a crouch or crawling position.”
According to the DOD document, the final kit consisted of:
Headlamp: The primary light source consists of a 6-volt headlamp mounte don the front of the fatigue cap. A bite-type on-off switch turns the light on and off.
Communication system: A highly sensitive bone conductor microphone may be attached to the inside top of the fatigue cap, work on the bone in back of the head, or strapped around the throat. Reception is provided by an earpiece. Lead terminals from the trailing wire are secured to the pistol belt near a wire reel which is attached to the belt. The system may be used with the TA312/PT telephone or another bone conductor system.
Revolver: A .38 caliber, 4-inch barrel revolver is provided with each kit. A silencer and a small high intensity aiming light is mounted on the weapon. Ear valves are provided to protect the user’s ears when the weapon is fired.
The post says six kits were requested by the USARV that were then passed on to deployed units in the field and testing soon revealed that the kit wasn’t quite where it needed to be.
The DOD document lists the following problems with the kit:
The bite switch for the headlamp didn’t function properly
The weight of the headlamp and rubbing against the tunnel roof cause the hat to slide down over the user’s eyes, especially after the user began to sweat. The headlamp also made it difficult to point the light beam where necessary when a tunnel changed direction, and the hat brim could block a portion of the lamp’s light.
Users had trouble keeping the earpiece for the comms system in place and the wires were easy to snag on…pretty much anything. For the comms system to be of any use, it had to be hardwired to a field telephone via a reel of comms wire that had to be carried on the gunbelt and trailed behind the user.
Regarding the .38 revolver, this is what users had to say:
“All four units indicated that the revolver, with silencer attached and aiming light mounted, is large and awkward. (One unit) reported the aiming light was effective, one stated it was ineffective, and one stated that it served little or no purpose because its light was diffused and over-shadowed by the larger and stronger miner’s lamp.
“The holster, while desirable, was considered large and bulky by three of the four reporting units. A general comment was that the holster did not fit snugly and could not be securely fixed to the pistol belt.”
Three units that tested the kit reported that the suppressor was ineffective (the fact that they packaged it with a set of ear plugs should tell you how much confidence even the kit’s designers had in the suppressor), but the report notes the users were forced to use full-load ammo instead of the recommended half-loads, which weren’t available—though it’s doubtful it would have made much difference. Suppressors don’t work very well on revolvers because of all the gas and flash that escapes via the cylinder gap instead of being directed out the muzzle.
Testers also recommended that a knife be added to the kit, for obvious reasons, and for probing for mines and other booby traps during tunnel exploration.
Yet somehow, the report resulted in a satisfactory review from the DOD and about 250 of the kits eventually made their way to Vietnam, though it’s not known if they saw much or any use.
Later, S&W tried to solve the same problems for tunnel rats in a different way with the Quiet Special Purpose revolver (QSP). The gun was a highly modified S&W Model 29 in .44 Magnum. According to David E. Petzal at Field & Stream, the standard barrel on the revolver was replaced with a “1.372-inch-long unrifled tube and the cylinder was bored out to accept six massive steel cartridges, each loaded with 15 tungsten-steel shot that developed a muzzle velocity of 750 fps.”
The pellets were housed in a sabot that was propelled by the force of a primer only—the cartridge contained no additional propellant. As a result, the pistol had no flash and made very little noise compared to a .45 ACP. However, this gun too was ultimately a failed experiment, and only four QSP revolvers were made.
So, in the end, tunnel rats mostly ended up using an M1911A1, a knife, and an angled handheld flashlight when they went into the darkness—and whatever other sidearms they could scrounge.
Because they weren’t as loud, didn’t produce as much flash, and were more resistant to being dragged through the muddy tunnels cut into the Vietnam jungle than M1911s, .38 revolvers were most prized among tunnel rats, who also used cut-down M1 Carbines, if possible. Some even had machinists construct custom suppressors and a number of tunnel rats used personal weapons, including everything from small automatics to sawed-off shotguns, according to smallarmsreview.com.