Manufacturing Marks of WWII

© Jerry Penry

The Browning M2 machine gun was the most widely used weapon on the American bomber and fighter planes of WWII. Due to the high demand of ammunition for this gun, many companies began producing the .50 caliber round to keep the supply available.


The .50 caliber round is 5.5" (140mm) long with seated bullet. The casing alone is just under 4" (100mm) long. The primer end of the casing where the headstamp is located is 0.75" (19mm) diameter. The bullet is typically 2.25" (55mm) long with 0.75" (19mm) seated into the casing. The bullet diameter is 0.50".

Remington Arms 1942 headstamps.

Known manufacturers and headstamp codes of companies producing .50 caliber ammunition during WWII.

DI = Defence Industries Limited - Ajax, Ontario, Canada.
DM = Des Moines Ordnance Plant - Ankeny, Iowa.
FA = Frankford Arsenal - Philadelphia, Pennsylvania.
K = Kynoch Works - Witton, Birmingham, England.
KS = Kelly Springfield, Allegany Ordnance Plant - Cumberland, Maryland.
LC = Lake City Army Ammunition Plant - Independence, Missouri.
LM = Lowell Ordnance Plant - Lowell, Massachusetts.
M = Milwaukee Ordnance Plant - Milwaukee, Wisconsin.
RA = Remington Arms - Bridgeport, Connecticut.
SL = St. Louis Ordnance Plant - St. Louis, Missouri.
SR = Royal Ordnance Factory - Spennymoor, United Kingdom.
T = Tikkakoski Arsenal - Finland.
TW = Twin Cities Ordnance Plant - Minneapolis, Minnesota.
U = Utah Ordnance Plant - Salt Lake City, Utah.
UT = Utah Ordnance Plant - Salt Lake City, Utah.
WRA = Winchester Repeating Arms - New Haven, Connecticut.

*** Headstamp Images Only ***
(No Text)

The headstamps shown below do not reflect all of the .50 caliber casings that were made during WWII.
If you have additional information or would like to contribute an additional or better photo of a headstamp,
please contact me.

Refresh your screen if one or more of the images below do not appear.

Defence Industries Limited
The town of Ajax, in Ontario, Canada, was founded in 1941.
It was the largest defence industry in North America for the Allies.


Des Moines Ordnance Plant
Operated by the U. S. Rubber Company from 1941-45.

1942                  1942

1943               1943               1943                1943

1943               1943               1943               1943

1944             1944               1944

1945               1945               1945

Frankford Arsenal
Operated as a major ammunition manufacturing plant from 1816 - 1977.


1940               1940

1941               1941

1942               1942

1943               1943               1943

1944                   1944                1944

The above "TEST" casing is still a mystery and may not be WWII-era.

Kynoch Works
A British company that traces its beginnings back to 1856, this manufacturer had an estimated 20,000
employees working at Witton by 1943 and was a prime target for the Luftwaffe during WWII.

Several inquiries as to this round, which at first glance appears to be a .50 caliber, prompted a
mention of it here for collectors. The round is most distinguishable by the belted casing.
It was used for the British Boys Anti-Tank rifle, a fearsome bolt action rifle with a considerable recoil.
It was phased out in favor of the PIAT Anti-Tank Projector around 1943.

1939               1939

1940               1941


The belted casing of the Kynoch .55 caliber.

Kelly Springfield, Allegany Ordnance Plant
Operated by the Kelly Springfield Tire Company in 1943-44.



Lake City Army Ammunition Plant
Established by Remington Arms in 1941 to manufacture and test small caliber ammunition for the U.S. Army.


1942                 1942

1943                 1943                1943                1943

1944                 1944                 1944                1944

1945              1945


1943                 1944

Note: The above images are examples of broken dies on the letter "L".

Lowell Ordnance Plant
A small arms plant that operated under contract from the
Remington Arms Company between 1942 and 1943.


1943             1943                 1943

Milwaukee Ordnance Plant
Operated by the U. S. Rubber Company from 1942-43.


1943               1943               1943

Remington Arms
Founded in 1816, this company is the oldest in the United States which still makes its
original product, and is the oldest continuously operating manufacturer in North America. The RA 41 .50 CAL Z shown below was produced during a British RAF contract to supply ammunition for the American made B-17 bombers used by the RAF.


1941               1941             1941
(The far right casing was found among many RA 41 casings, so believed to be Remington Arms).





St. Louis Ordnance Plant
This plant was operated as the United States Cartridge Company as a division of Western Cartridge Company. They were only a few miles east of the East Alton plant operated by Western.
This plant manufactured 6.7 billion .30 and .50 cartridges for the War.


1942               1942

1942 Overstrikes

1943             1943




Royal Ordnance Factory. Spennymoor, United Kingdom (1913-1945).

1942             1942



Tikkakoski Arsenal - Finland

Tikkakoski was the first private arms manufacturer in Finland. The arms factory was closed in 1987. Beretta Group owns now the Tikka arms brand. The United States supplied Brewster Buffalo fighters to Finland who was at war with Russia from 1941-1945. The symbol is a circle with crossed arrows. The 12.7 is the equivalent size of the .50 caliber in millimeters.


Twin Cities Ordnance Plant
Operated by the Federal Cartridge Company from 1941-45.
This company produced .30, .45, and .50 caliber ammunition.

1942               1942               1942               1942               1942               1942

1943               1943               1943

1944                1944

1945           1945

(Broken Dies)

Utah Ordnance Plant
Operated by the Remington Arms Company.

1942                 1942                1942

1943               1943

1944                 1944?

Winchester Repeating Arms

1942                  1943

This headstamp is of an unknown Russian manufacturer. The casing is a 12.7mm, the equivalent to the .50 caliber.



Pre-WWII Headstamps



Other-Foreign Headstamps
(Non WWII)


South Korean


Regular M2 casing (top) shown with a short casing.
The short casing is from a .50 cal spotter rifle attached the 106mm recoiless anti-tank weapon. Its use was to simulate the exact trajectory of the main gun so to minimize misses.

Steel links connect the casings together.
Links also have manufacturing marks.
Click the link below to enter the "LINKS" website.


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Wikipedia Website           Wikipedia Website
(.50 Caliber Shell)            (.50 Caliber Gun)

Thanks to the following contributors who have supplied information or images for this website:
John Anderson, Danny Benger, Andrew Brock, William Browne, Fred Butt, Chuck Clark, Dave Clarke, Chris Collins, Mike DeFazio, Dave Dengel, John Donovan, Gary Driscoll, Chris Federico, Alicia Garrett, Jay Holton,
Scott Humphries, Koen Jansen, Susan Lemme, Kori McCaskill, Glenn Morgan, Gary Muckel, Joe Pilbeam, Gary Piney, Gerald Stutts, Gene Thomsen, Ian Wood, Neil Wright, Blaz Zarnik.

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