Cartridge identification is important to anyone who works with ammunition cartridges, whether it's reloading or collecting. While it isn't foolproof, often the easiest way to identify a cartridge is to look at the headstamp, if there is one, because in many instances that will tell you exactly what it is.
The headstamp is the stamped markings on the head of the cartridge. Information that can be obtained from the headstamp is extremely varied and depends on the intended purpose or use of the cartridge and who manufactured it. Headstamps consist of one or more parts or information elements. Cartridges intended for sporting or civilian use usually have two elements; one identifies the specific chambering, the other identifies the manufacturer. Military cartridges can have from one to five elements, including cartridge, date and place of manufacture plus other identifying markings.
Some headstamps are segmented, that is, these have one or more segment lines that divide the head into two to four equal parts. This usually indicates an older cartridge, since most countries discontinued segment lines shortly after World War I. The location of the elements is most conveniently indicated by its clock-face orientation, with 12 o'clock at the top, 3 o'clock at the right, 6 o'clock at the bottom and 9 o'clock at the left. The basic U.S. military headstamp prior to World War II had two elements, with the factory code at 12 o'clock and the date at 6 o'clock. Rapid expansion of ammunition manufacturing facilities as the result of the war introduced many new designs without any effort at standardization. Some used three elements spaced equidistant from each other while others adopted a four-element system located at 12, 3, 6 and 9 o'clock. Also the location of the factory code was changed, in some instances, to 6 o'clock or other locations.
Worldwide, there are over 800 military headstamps in existence plus some 400 or more commercial headstamps that have existed at various times. Obviously, this is a complex and highly specialized field. Since it would require another whole book to adequately cover the subject, it is quite impossible to include more than a few examples. Headstamp markings of the principal American ammunition manufacturers are as follows:
Federal Cartridge Co.
Rimfire, AL EP, G or G, HP, F, XL, XR and WM Centerfire, FC
General Electric Co.
GE plus date (military)
Newton Arms Co.
NA plus caliber (Made by Rem.)
Peters Cartridge Co.
Rimfire, P or PETERSHV Centerfire, P, PC, P.C., PCCO
PETERS E. Remington & Sons
E REMINGTON & SONS (1870-1890)
Remington Arms Co.
U, UMC, REM, REM*, UMC, R-P, RAH
Robin Hood Ammunition Co.
R, RHA, R.H.A. Co.
Savage Arms Co.
S.A. Co. (made by U.S. Cartridge Co.)
Savage Repeating Arms Co.
S.A. Co., S.R.A.C.O.
Richard Speer Manufacturing Co.
Union Metallic Cartridge Co.
U, UMC or R B (Purchased by Remington in 1911)
United States Cartridge Co.
US, U.S., *U.S CARTRIDGE CO*,U.S.C. CO. or RL (1869 to 1936)
Western Cartridge Co.
SUPER X, SUPER-X, W, WCC, W.C. Co. WESTERN
W, H, SUPER SPEED, W.C. Co.
W-W, super speed
There were about 15 other companies that manufactured ammunition at various times, particularly during the 1860-1900 period. Also a number of private firms manufactured military ammunition during World War I and II.