Ammo Basics 101: What do the markings on a cartridge headstamp mean?


***When handling ammunition (live rounds, spent cases, etc.) please be sure that all safety precautions are taken to safeguard against injury.  Also please be sure to thoroughly wash hands after handling any ammunition.  PSA Rule of Thumb:  Wash hands first in cold water (warm water opens up the pores of the skin and allows lead particles to enter).

The PSA Creative department has received several requests from our devoted readers to post a brief explanation about just what exactly the markings on a cartridge headstamp mean.  As you guys know, we love our readers and we love talking guns!!!  By popular demand here we go!!!

Usually the markings on the headstamp of a centerfire cartridge such as the one above will provide the manufacturers name and the caliber that the cartridge is cased for.  For instance, this cartridge was manufactured by Blazer and this particular round is cased for .40 S&W.  The 40 that is stamped indicates the diameter of the bullet (in this case .40 inches) and S&W indicates the company that designed the caliber: Smith & Wesson.


The picture above is another example of a centerfire cartridge that shows different markings.  On this rifle cartridge, we can tell that Winchester Company manufactured the round, and it’s chambered in 30-06 (pronounced “thirty-aught-six” or “thirty-oh-six”) Springfield.  The 30 indicates that the diameter of the bullet is .3 inches and the 06 indicates the year the cartridge was adopted: 1906.  Springfield is the arms company that created the caliber (notice that there is a difference between the company that manufactures the round and the company that created the caliber).


The headstamp of a rimfire cartridge will look a little different than that of centerfire cartridges.  The example provided here is indicative of most rimfire cartridges; usually only displaying one or two letters.  This particular cartridge has the marking “U” which indicates that the Union Metallic Cartridge Company manufactured this round.  No caliber information is included on these headstamps as they usually have a much smaller diameter than that of centerfire cartridges.

***Please be advised that when selecting ammunition for a particular firearm, PSA gives the following Rule of Thumb:  Match the stampings on the ammo, to the stampings on your firearm, to the label on the box of ammo.  ONLY use ammo that is indicated by the firearm manufacturer as safe for that particular firearm.

As with any thing that pertains to personal defense firearms please do thorough research.  This post is most definitely not the complete guide for reading headstamps.  Please understand that any wildcat cartridges, reloads, etc. will have different types of headstamp markings and there is no standardization for these rounds.

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To all of our readers and shooting friends….remember to watch your six and stay low

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