Colt Model 1921, 1921A1, 52 & 52A water-cooled .50
Official wording
Colt, Model 1921, Model 1921A1, Model 52, and Model 52A, cal. .50, water-cooled machinegun, as originally mfd. by Colt and bearing the original S/N with the letter "C" prefix.
What this entry requires
- ATF REQUIRESMade or imported as stated: “as originally mfd. by Colt and bearing the original S/N with the letter "C" prefix”
- ATF REQUIRESYour serial number is one ATF listsATF: “bearing the original S/N with the letter "C" prefix”
- INFOATF states no date; production was about 1921–1945.
- INFOStill an NFA firearm; only registered examples transfer, with ATF approval (26 U.S.C. 5812, 5861).
Editorial facts · Our research
- Country
United StatesBasis: no citation - Manufacturer
- Colt's Patent Fire Arms Mfg. Co.Basis: the ATF wording
- Type
- MachinegunBasis: the ATF wording
- Action
- Select-fire / autoBasis: the ATF wording
- Caliber
- .50 BMGBasis: the ATF wording
- Made
- “C” serial prefix · c. 1921–1945production; ATF states no dateBasis: outside reference ¹
- Service
- Military
Source
- Official wording
- ATF P 5300.11, April 2025 edition · Section IV · PDF p. 83 ↗ · ATF original ↗
- Entries
- 1 line
- Verbatim check
- Checked against the PDF text before every release
- Editorial facts
- Confidence: Medium · Last revised 17 October 2026 (Data-trust review) · How we rate confidence
- References
- 1. Wikipedia, “M2 Browning” ↗, years: water-cooled .50 M1921 used experimentally 1921–1937; Colt made M1921A1 prototypes in 1933 and began M2 manufacture in 1933
- Fact tags
- ATF the ATF wording states it.
- REF ¹ an outside reference supports it; the number points to the list of references.
- ESTIMATE an approximate or indirect reading, for example the production range of the base model.
- NO CITATION we haven’t attached a reference for this fact; it’s our editorial reading, not ATF’s.
- Source checked
- 20 October 2026: ATF’s page still lists the April 2025 edition
- Corrections
- 1 change · see below
Correction history
- Data-trust reviewEditorial confidence: Low → Medium. Re-rated after supporting references were added or re-checked.
Historical context
Image: Wikimedia Commons, “Twin .50-calibre AA Machine Guns, Army Museum, Halifax Citadel, Halifax, Nova Scotia.JPG” by Skaarup.HA, CC BY-SA 4.0. Retrieved October 2026.
Summary: Wikipedia, “M1921 Browning machine gun”. Text CC BY-SA 4.0.
FROM WIKIPEDIA
The M1921 Browning machine gun was a water-cooled .50-caliber machine gun designed by John Moses Browning. Development began in 1917 when Browning scaled up his .30-caliber M1917 to chamber a .50-caliber round, resulting in a prototype tested in 1918. The M1921 entered limited service with the United States Army and Navy in the late 1920s, and was succeeded by the M2 Browning in 1933.