David Marshall Williams - Overview

David Marshall Williams

of the

The Legend
Carbine Williams


Incorrigible Youth
The Murder, & Whodunnit:


Prison Time


Ordnance, Colt, & Remington


at Winchester

1939- ___

End Years
and Museums


The Ordnance Department, Colt, & Remington


Patent for the Short Stroke Gas Piston & Floating Chamber

Williams filed his first patent applications on February 2, 1931:

  • Automatic Firearm
  • patent # US2090656 granted 24 Aug 1937
  • Safety Mechanism for Firearms
  • patent # US2174851 granted 03 Oct 1939
  • Extractor Mechanism for Firearms
  • patent # US2204289 granted 11 Jun 1940
  • Sear Mechanism for Firearms
  • patent # US2242496 granted 20 May 1941

    The patent for the Automatic Firearm was for the various ways in which Williams envisioned firearms using the gas generated at the front of a fired cartridge to operate the weapon. The patent has diagrams depicting the floating chamber gas piston as used on his modified Remington Model 8 for both a centerfire cartridge firearm and a rimfire cartridge firearm, his modified Remington Model 8 with the forward long stroke action barrel, and most importantly as relates to the U.S. Carbines, a fourth firearm wherein the short stroke gas piston was moved out of the firearm chamber and onto the right side of the firearm. This fourth design eliminated the floating chamber and channeled the high pressure gas out of the breach and into an external gas piston housing on the right side of the firearm, where it propelled the short stroke gas piston directly into the bolt handle to operate the action. The other three patents were unrelated to this patent or the U.S. Carbines.

    Patent # US2090656 diagram of what Williams described as a vibrator, instead of "short stroke gas piston", to operate the action of a firearm.

    The threads on the outside of the vibrator can be confusing until it's realized the vibrator, like the floating chamber gas piston on his
    modified Remington 8 constructed in prison and shown above, does not rotate and moves only the short distance of the
    difference in the width of the vibrator threads and gas piston housing grooves
    (illustration by author based on patent drawing)

    The Ordnance Department

    Browning Machine Gun
    .22 caliber Conversion

    In 1931 U.S. Army Ordnance put out a notice requesting submissions of a .22 long rifle caliber conversion of the Browning 1917A1 machine gun, to be used in training military personnel. Williams was the only one to respond to the request with a bid submitted 12 Mar 1932. Williams was awarded a contract for one conversion followed by a second contract for five more after the first was submitted. Ordnance supplied Williams with the 1917A1's to be converted. Once the gun was converted it was a dedicated .22 long rifle version of the 1917A1 and not interchangeable with the .30 caliber version. The Williams design used belt fed .22 long rifle ammunition and was designated the Trainer, Machine gun, caliber .22 M1.

    Trainer, Machine Gun, Caliber .22 M1
    S/N 1 converted by Springfield Armory 21 Oct 1934
    (photo courtesy of the Springfield Armory Museum)

  • Gun
  • application submitted 19 Mar 1935 patent # US2027892 granted 14 Jan 1936
  • Belt Feeding Means for Guns
  • application submitted 19 Mar 1935 patent # US2027893 granted 14 Jan 1936

    Floating Gas Chamber with multiple gas ducts running lengthwise. The ducts vent gas from the front
    of the cartridge casing to force piston and bolt rearward to operate the action.

    Browning M1 .22 caliber Machine Gun showing Floating Gas Chamber closed (top) and open (bottom)

    Production of the gun was by Springfield Armory with serial number 1 being converted from a Remington M1917A1 (s/n 42014) on 21 Oct 1934. The weapon was received by Springfield Army Museum 06 Jun 1935. Production was from 1934-1941 with use continuing throughout WWII. The total quantity produced is not known.

    Improved Versions

    On 17 Jun 1936 Filser D. Hoppert, William R. Bull, and Clarence E. Simpson of Springfield Armory submitted an application for a patent of a .22 caliber conversion unit that allowed the M1919A1 to be converted back and forth from .30 caliber to .22 caliber rimfire (patent # 2108817, granted 22 Feb 1938). The conversion unit shared a number of things in common with the original Williams design, including the Williams patented floating chamber to operate the action.

    As opposed to a belt fed .22 caliber weapon, these units used a belt with .30 caliber casings adapted to hold the .22 cartridges within the casing. This allowed the weapons to operate with the .30 caliber belt feed mechanism. These were designated the Trainer, Machine Gun, Caliber .22 M3 (for the 1919A1). Subsequent versions were created for the 1919A4 (Caliber .22 M4) and AN-M2 (Caliber .22 M5 .30).

    Conversion units utilized .30 caliber casing adapters into which the .22 cartridges were inserted

    Production of the M3, M4, and M5 is estimated as 1940-1955. In 1955 the M60 machine gun replaced the 1917A1, 1919A1, and 1919A4. How many were manufactured is not known. Further information on these conversions may be found on the website of BeltFedPlus.

    Williams Design Modified and Improved to Interchangeable Kits

    Browning Machine Gun
    Caliber .22 M3 Trainer &

    Browning Machine Gun
    Caliber .22 M4 Trainer
    (photos courtesy of Springfield Armory Museum)


    Service Model Ace

    In 1931 Colt introduced the Colt Ace, a .22 long rifle rimfire caliber version of Colt's 1911A1 .45 ACP pistol. This pistol was specific to the .22 rimfire cartridge with a recoil equivalent to its cartridge, which frequently failed to operate the slide action and chamber the next cartridge.

    Colt contracted Williams to modify the Colt Ace using his floating chamber design, producing the Colt Service Model Ace in .22 long rifle. The Colt Service Ace produced a recoil nearer to that of the .45 ACP cartridge than the .22 rimfire cartridge it used, making it a more realistic weapon for training in using the Model 1911A1 pistol in .45 ACP.

    (Colt Service Model Ace sn SM1513, copyright Coltautos.com)

    Short Stroke Gas Piston Floating Chamber

    • Automatic Firearm, application submitted 26 Aug 1933, patent # US2090657 granted 24 Aug 1937

    11,961 Colt Service Model "ACE" pistols were manufactured between 1935 and 1945. Their parts were fully interchangeable with the .45 caliber M1911A1. Colt reintroduced the Service Model Ace in 1978 and continued production until 1982.

    Improved Version

    The Colt .22 - .45 Service Model Conversion Unit (Ace)

    In 1938 Colt introduced a conversion unit for converting the .45 caliber 1911A1 pistols to .22 long rifle caliber for training purposes. This conversion kit eliminated the receiver used for the Service Model Ace. The kit was compatible with the 1911A1 receiver and parts. Production of these kits continued into 1946.

    Stoeger's "The Shooter's Bible" 46th Edition

    The Colt Service Ace and conversion kit were the first known to reveal a consistent shortcoming of the floating chamber short stroke gas piston when located within the breach (as opposed to the gas piston being outside the chamber as it is on the U.S. Carbines). The powder residue and use of soft lead bullets frequently clogged and jammed the movement of the floating chamber gas piston.

    Remington Arms

    Model 550
    .22 Caliber Rimfire Rifle

    The Model 550 was designed and developed by Remington employees K. Lowe and C.C. Loomis, who used the Williams floating chamber as described in his first patent. This rifle was the first semi-automatic rimfire rifle capable of operating with either the .22 short, .22 long, or .22 long rifle cartridges. The patents for this rifle were held by Crawford C. Loomis, assignor to Remington Arms Company. Both patents refer to the use of the floating chamber as described in patent US2090656, the patent held by Williams for his floating chamber short stroke gas piston concept.

    At various times and in various publication Williams claimed he had designed and developed this rifle. The rifle he designed for Remington was not the rifle that became the Model 550. Clearly they did choose to use his floating chamber short stroke gas piston design, for which they paid royalties to Williams.

  • Firearm
  • application submitted 31 Oct 1940patent # US2353679 granted 18 Jul 1944
  • Firearm
  • application submitted 31 Oct 1940 patent # US2356491granted 22 Aug 1944

    Remington Arms Model 550, 22 Caliber Rimfire Rifle

    Bolt is in the open position
    (adapted from Remington Model 550 Instructions for Operation and Care)

    Remington Model 550 Floating Chamber

    .22 Short - .22 Long - .22 Long Rifle - .22 Long Rifle (CCI Stinger)

    .22 Short inside Floating Chamber

    Production was from 1941-1970 during which approximately 764,573 were manufactured.

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