Answer: Ammunition type.
The cartridge on the right has a headstamp that says ‘LC 99’ with a symbol that consists of a cross in a circle.
A headstamp is the markings 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: 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).
List of U.S. Army munitions by supply catalog designation …
MIL-STD-1168 – Wikipedia
ROF Radway Green – Wikipedia
MIL-STD-1168 – Wikipedia
The MIL-STD-1168 is a set of standard codes used to identify munitions.
The Ammunition Identification Code (AIC ) was a sub-set of the Standard Nomenclature List (SNL).
Microstamping is a proprietary ballistics identification technology. Microscopic markings are engraved onto the tip of the firing pin and onto the breech face of a firearm with a laser.
The examination of the cartridge relies on the unique tool marks left by the various parts of the weapon including the firing pin and the ejector in semi and fully automatic …