We were sure we’d written about this before, but if we did, we can’t find hide nor hair of our previous report. So, just maybe we haven’t. Recently, we got some new information, and will share it with you.
The QSPR is an extremely rare special-purpose revolver that was developed and produced by the AAI Corporation. Formerly Aircraft Armament Incorporated, the name was abbreviated officially because they never sold any of their aircraft armament concepts. They worked on several ill-fated futuristic small arms of the 1960s (like the SPIW) and one very successful one, the M203 40mm grenade launcher.
The QSPR was made from a Smith & Wesson Model 29. Frames in white were provided to AAI by Smaith, and they were modified with a .40 caliber smoothbore barrel and the cylinders were bored out to 0.528″, leaving a minimal web between chambers. (The lost strength was made up for by the strong cartridges). The weapon was innocent of any sights — it was meant to be used at contact range, inside tunnels, although accuracy to 25 feet was claimed (and Vietnam users reported it was more accurate than their .38 revolvers). Both standard large-frame Smith and aftermarket or custom grips were tried.
The objective was to provide a weapon for tunnel combat, a weapon with reduced blast, noise, flash and yet increased lethality over the standard pistols and revolvers of the era. It was designed to produce a column of lethal buckshot at very close range, with no flash and very limited blast. Noise in the enclosed tunnels was equivalent to a .22LR firearm outdoors, which was a great improvement over the eardrum-shattering blast of the alternative, the M1911A1 .45 pistol.
Eleven QSPR revolvers were made, of which one was retained by AAI (and is still reportedly retained by a successor, Textron systems). Ten were deployed in 1969 for combat testing in Vietnam; one was reported as a combat loss. Of the existing revolvers, apart from the AAI reference piece, two (#5 and an unknown example) are in a US Army museum, and one is in the ATF reference collection. It was the missing Vietnam gun, which was used in a homicide in California and recovered, according to Dockery.
THE QSPR seems very sophisticated for a first shot, and that’s because it wasn’t. A previous S&W based tunnel revolver was a Model 10 M&P with reduced cylinder gap, a suppressor and an aiming light. It was part of a comprehensive suite of gear assembled by the boffins in the Army’s Land Warfare Laboratory and called the Tunnel Engagement Kit, illustrated here. (The vane switch in the guy’s mouth turned on the VC aiming point on his cranium). You can almost hear them saying, “Do bring it back this time, Mr Bond.” But this bit of lab genius was not what the guys needed, and so the boffins went back to the lab and cooked up the QSPR.
Ladies and gentlemen, here is a recent photograph of a unicorn — a live QSPR round. This is believed to be the last and only live round in existence (the ATF caused the destruction of most of them maintained by AAI and the military museum system by declaring them suppressors). The material is high-carbon steel, because the case contains the entire energy of the round, inside a piston. An end cap is screwed on the base of the round; threads in the muzzle end act as a trap to catch a piston. A plastic sheath called a “sabot” wraps around the projectiles and is discarded, much like the sabots used with subcaliber projectiles, when the projectile column exits the muzzle. The muzzle end of the round has a silicone (we think) material applied as a sealant.
The round has a dark finish which appears to be some kind of high-tech proto-melonite coating, although most resources describe the ammo as “blued.”
This is a schematic of the round from what appears to have been the final report on the weapon after development and combat testing in Vietnam. The report recommended further improvements and then general issue to Infantry and Ranger units. Those improvements were not pursued, and the firearm was never manufactured.
The high pressure inside the round breaks the “rim” of the piston free of an annular slot that initially retains the piston in the rearward position and forces it forward, ejecting the sabot-contained shot load, until the pressure snaps the piston rim into a similar annular slot positioned to receive it, and drives the “nose” of the piston into the muzzle-end threads. These two engagements arrest the piston’s forward motion. One purpose of the rearward slot is to retain the pistol and prevent it from sliding and ejecting the payload during normal gun handling.
This is the muzzle end of the round. As you can see, the sabot (or the sealant atop it) comes closer to the muzzle than indicated in the diagram.
This is the breech end. As you can see, there are no markings on the round. The revolvers themselves were marked with the S&W trademark, so we suspect the lack of markings on the ammunition was more a reflection of the toolroom nature of the project than in any attempt to make a deniable or clandestine weapon.
The missing detail from most of the reports, the reason the initial report was classified (albeit only at the Confidential level), and the cause of the QSPRs unusually high terminal effect for a handgun was in a material breakthrough. While most open source reports suggest that the projectiles in the shot column were lead, steel or even tungsten (Wolfram to you Europeans), they were actually depleted uranium.
DU is uranium from which the fissionable isotopes have been removed. It is a side product (a waste product, really) of uranium enrichment for weapons production and has a number of properties making t an excellent choice for projectiles.
While the US was developing the QSPR, Soviet scientists were working on similar captive-piston technology. But in the end, the complexity and cost of the system seems to preclude it from ever being made in more than nominal numbers. The ATF’s Firearms Anti Technology Branch has rendered research on this type of weapon in the USA functionally impossible; Russian designers, who have produced a great many widely varied quiet weapons, seem also to have moved on away from this technology.
The resources below are all worth reading but the most valuable is certainly the official report:
Sources & Resources
Dockery, Kevin. Tunnel Weapon: The Bang in the Dark. Small Arms Review, Volume 5 Number 9. Retrieved from: http://www.smallarmsreview.com/display.article.cfm?idarticles=2423
Popenker, Maxim. Smith & Wesson / AAI Quiet Special Purpose Revolver / QSPR / tunnel revolver (USA), World.Guns.Ru. Retrieved from: http://world.guns.ru/handguns/double-action-revolvers/usa/qspr-silent-revolver-e.html Note that Max’s report on the QSPR is pretty accurate but his photoshop job has the barrel a tad too long.
Schreier, Conrad F., Jr. The Silenced QSPR Revolver: An Answer to an Age-old Military Problem. Guns and Ammo Magazine, “Ordnance Department” feature, Guns & Ammo Magazine, October 1971, p. 64. Copy: Guns & Ammo QSPR Article .pdf
Weddington, David E., LTC, IN. Final Report: Tunnel Weapon. Army Concept Team in Vietnam (ACTIV), (Linked above).