A headstamp is the marking on the bottom of a cartridge case designed for a firearm. It usually tells who manufactured the case. Military headstamps usually have only the year of manufacture .
A letter, number, or alphanumeric code indicates the place of manufacture:Sharpe, Philip B. Complete Guide to Handloading (1953) Funk & Wagnalls p.75 Other codes may indicate metal suppliers (like France or The Netherlands) or the percentage of copper in the alloy the cartridge case is made of (like Poland and Germany).
United States military cartridges
US arsenals World War II manufactured cartridges with a single "4" as the year of production were made in 1944. The demand was so great for cartridges that most manufacturers just ground off the "3" on the "43" stamp to save time. Most wartime plants were closed by the end of the war. Some cartridges with a single "5" were made in 1955.
AO or KS Allegheny Ordnance Plant (Kelly Springfield) (1943–1945) – Cumberland, Maryland; Operated by Kelly-Springfield Tire Co., a division of Goodyear Rubber. Conversion back to rubber tire production began in 1944. CB Curtis Bay Ordnance Depot (CBOD) (1917–1957) – Baltimore, Maryland. Used to store, examine, overhaul, and repack ammunition. DEN Denver Ordnance Plant (1941–1945) – Denver, Colorado: a division of Remington Arms. DM Iowa Army Ammunition Plant (January 1942 to July 1945) – Des Moines, Iowa: a division of US Rubber Co. EC Evansville Ordnance Plant (Chrysler) (June 1942 to April 1944) – Evansville, Indiana: a division of Chrysler-Plymouth. They manufactured brass-cased ammunition. From 1943 to 1944 it manufactured steel-cased .45 ACP ammunition. ECS Evansville Ordnance Plant (Chrysler-Sunbeam) (1942–1944) – Evansville, Indiana: a division of Sunbeam Electric Manufacturing Company. Chrysler bought the plant to keep up with demand. It loaded cartridges made at the Evansville-Chrysler plant across town and then packed them in shipping crates for shipment. In November, 1943 it was the first plant to package ammo in vacuum-packed metal cans. In the Spring and Summer of 1944 it was employed in inspecting and repacking .45 ACP and .30 Carbine ammunition. EW Eau Claire Ordnance Plant (August 1942 to December 1943) – Eau Claire, Wisconsin a division of US Rubber Co. FA Frankford Arsenal (1816–1977) – Philadelphia . HAW Hawthorne Naval Ammunition Depot (1926–1977) – Hawthorne, Nevada, USA. HW- Hawthorne Army Ammunition Plant (1977–present) – Hawthorne Nevada, USA. From 1977 to 1992 it was designated the Hawthorne Army Ammunition Plant (HWAAP) and from 1992–present it was redesignated the Hawthorne Army Ammunition Depot (HWAD). KOP Kingsbury Ordnance Plant (1941–1945; 1950–1959) – Kingsbury, Indiana. LC Lake City Ordnance Plant (operated by Winchester Arms) (1941–1945; 1951-Present) – Independence, Missouri; A sub-contractor originally owned by Remington Arms. It is currently owned by the US Government and operated by Northrop Grumman Innovative Systems. LM Lowell Ordnance Plant (1942–1943) – Lowell, Massachusetts LOD Letterkenny Ordnance Depot (1942–present) – Letterkenny, Franklin County, Pennsylvania. It was renamed Letterkenny Army Depot in August 1962. LOP Louisiana Army Ammunition Plant (1942–1996) – Doyline, Webster Parish, Louisiana, USA. LS Lone Star Army Ammunition Plant (1941–2009) – Texarkana, Texas, USA. M Milwaukee Ordnance Plant (August 1942 to December 1943) – Milwaukee, Wisconsin: Operated by US Rubber Co. P, PC, PCC Kings Mills Ordnance Plant (Peters Cartridge Company) (1942–1944) – Kings Mills, Ohio: A sub-contractor owned by Remington Arms from 1934 to March, 1944. It was converted to only produce .30 Carbine ammunition in 1943 and produced more than Lake City by 1944. It was closed down in March, 1944 to consolidate production at more centrally located plants. The site was converted to press vinyl 78 rpm records for Columbia Records from 1944 to 1949. It was then used for storage from 1949 to 1968. PBA Pine Bluff Arsenal (1941–present) – Pine Bluff, Arkansas, USA. ROP Redstone Ordnance Plant – Huntsville, Alabama (1941–1949). Combined with the Huntsville Depot facility to form Redstone Arsenal in 1949. SL St. Louis Ordnance Plant (November 1941 to June 1945) (May 1951 -May 1954) Plant mothballed December 1969 – St. Louis, Missouri. SND Seneca Ordnance Depot (1941 - 1990s) - Seneca, NY. TW Twin Cities Ordnance Plant (1942–1945; 1950–1957; 1965–1976; 2002–2005) – Minneapolis. U or UT Utah Ordnance Plant (March 1942 to December 1943) – Salt Lake City; a division of Remington Arms.
Civilian contractors B.E.L.L. or BeLL Brass Extrusion Labs LTD - Bensenville, Illinois (1973-1989). Manufactured rare and obsolete hunting cartridges for Midway, Holland & Holland, Purdey, John Rigby & Co., and Westley-Richards. Made 9x51mm Mk217 SMAW tracer cartridges for the USMC and 7.62x39mm Ball cartridges for the US Army. Bought out by El Dorado Cartridge Corporation in 1988 and closed in 1989. FC or FCC Federal Cartridge Corporation (1917-?) – Anoka, MinnesotaDavis, William C. Jr. Handloading (1981) National Rifle Association p.21 NC National Brass & Copper Tube Co. (1917–1918) – Hastings-on-Hudson, New York. Manufactured .303 British ammunition during World War I. OMF Saint Marks Powder Co. (A division of Olin-Mathieson) – Saint Marks, Crawfordville, Florida. Made ball powder for their ammunition factories. It was sold off to General Dynamics in 1998. RA Remington Arms Company – Bridgeport, Connecticut RA H Remington Arms Company – Hoboken, New Jersey. RHA Co. Robin Hood Ammunition Company (1898-1915; 1915–1917?) – Swanton, Vermont. Founded in 1898 by Vermont governor Edward Curtis Smith along with Canadian investors as the Robin Hood Powder Company. It was originally located in a factory near the Missisquoi River but was later moved to Swanton in 1909 due to its location near railroad lines. Bought out by Remington in 1915 (becoming Remington-UMC Swanton but retaining the old headstamp) when it received a wartime contract to produce rifle ammunition for the French government. The French-style headstamp has the yearly quarter before the 4-digit year (e.g., 4-1917 would mean 4th Quarter (October, November and December), 1917). It employed 1,000 workers in three around-the-clock shifts. They either lived in Swanton or commuted by streetcar from nearby St.Albans. Remington closed the plant at the end of the war when the French contract was ended. US, USCCO United States Cartridge Company (1867–1936?) – Lowell, Massachusetts. Manufactured .303 British ammunition during World War I. Bought out by National Lead Company in 1911. Western Cartridge Company closed the Lowell plant in 1927 and moved its machinery to East Alton, Illinois. Western Cartridge would make the ammo and US Cartridge would distribute it under their brandname. SMC Symington Manufacturing Company - Headquarters at Baltimore, Maryland and production at Rochester, New York. One of its peacetime products was machinery for making autocannon and artillery shells. It made autocannon rounds. TZ Texas Foundries Inc. (1976–2009) – Lufkin, Texas. W, WC, or WCC Western Cartridge Company – East Alton, Illinois Manufactured .30-'06 Springfield ammunition during World War I and World War II. WMA Winchester Military Ammunition (Winchester Arms Co.) WRA Winchester Repeating Arms Company (a division of Western Cartridge Company) – New Haven, Connecticut. Manufactured .30-'06 Springfield and .303 British ammunition during World Wars I and II and .30 Carbine and .45 ACP ammunition during World War II.
Commercial cartridges The US military used commercial cartridges for its training rifles, non-standard weapons, and shotguns. These usually had different headstamps than the military ammunition (usually their civilian one) and were shipped in commercial crates rather than military packaging. ♦ Western Cartridge Company – East Alton, Illinois: F Federal Cartridge Corporation – Anoka, Minnesota H Winchester Repeating Arms Company – New Haven, Connecticut: P, PCCo or PETERS Peters Cartridge Company – Kings Mills, Ohio: R-P Remington-Peters – Lonoke, Arkansas (1970–present). Lonoke facility only produced centerfire ammo from 1970; took over rimfire production from Bridgeport in 1989. R--P Remington Peters – Bridgeport, Connecticut (1960–1989). Bridgeport facility only produced rimfire ammo from 1970, then finally closed down in 1989. REM-UMC Remington-Union Metallic Cartridge – Bridgeport, Connecticut (1911–1960). Renamed Remington-Peters in 1960. U Union Metallic Cartridge Company – Bridgeport, Connecticut (1873–1911): Merged with Remington Arms in 1911, but still used the "U" headstamp for shotgun shells and rimfire cartridges. U.S.C.Co. United States Cartridge Company – Lowell, Massachusetts (1867–1926). WRA CO Winchester Repeating Arms Company – New Haven, Connecticut
Competition-grade military cartridges Ammunition designed for military competitive shooting was made by a variety of manufacturers. MATCH Ammunition used for target shooting. It is also used by Designated Marksmen and Snipers because it is more accurate than regular rifle ammunition at long ranges. NM National Match. Match ammunition specially made for the Camp Perry National Rifle and Pistol shooting matches.
Special cartridges 7.92mm Mauser During World War II the Western Cartridge Company made 7.92mm Mauser ammunition for the Chinese Nationalists. The original Ball bullets made in 1942 had Gilding-Metal-clad jackets and the later Alternate Ball versions made from 1943 to 1944 had Gilding-Metal-Coated-Steel (GMCS) jackets. The Chinese numbers 七 (Qi, or "7") over 九 (Jiǔ, or "9") at the 9 o'clock position represent the bullet's caliber (7.9mm). The Chinese character 美 (Měi, or "Beautiful") at the 3 o'clock position is shorthand for 美国 (Měi-guó, "Beautiful Country"). (This was the term Chinese immigrants gave California in the 19th century – and, by extension, the United States). The 2-digit year of production (42, 43 or 44) is at the 6 o'clock position. The ammunition was bulk-packed in standard 20-round cartons without stripper clips to maximize the amounts delivered and the packaging was marked in the Chinese language. In 1944 there was a contract to make 30-million modified Springfield-type Mauser-compatible stripper clips which were bulk-packed in ammo cans. Due to the long transport times, the rough and mountainous terrain, and constantly changing battlelines, the order wasn't completely delivered until 1947.
.30 Caliber (.30-06 Springfield) In 1953, US Army Intelligence ordered 250 million rounds of .30-06 ammunition to be manufactured in large lots under unique arsenal headstamps.Small-Caliber Ammunition Identification Guide (U) Volume 1 (DST-1160G-514-81-Vol1) The case had red lacquer sealant around the primer annulus. The headstamp has a two-letter manufacturer code (10- and 2-o'clock) and the lot code (rather than the year) is the number 40 (at 4 o'clock) followed by a third numeral (at 8 o'clock). This was divided by radial segment lines, like that of a Square (or Hellenic) Cross, between the portions to look like they were of European manufacture. The cartridges were intended to be aid to anti-Communist insurgents and Allied forces equipped with US weapons. They were loaded in 5-round stripper clips in M1 bandoleers (holding 12 × 5-round clips in cardboard spacers, or 60 rounds each) packed in US Navy 20mm Mark 1 metal ammo chests (33 × 60-round bandoleers; or 1980 rounds each). The chests were painted Olive Drab Green with subdued black lettering. A | N | 40 | # | Twin Cities Ordnance Plant, Minneapolis, Minnesota. Loaded nine lots (headstamps 40|1 to 40|9) for a total of 91,000,720 rounds.