Actually, Ruag does introduce a marking/revealing substance that is visible on X-rays in the propellants of their ammo who are destined and sold only to law enforcement, they call it the SINTOX®-FORENSIS.
It’s supposed to help calculate the trajectory of the bullets, and to differentiate ammo shot by law enforcements from other perpetrators (i.e., during a shootout).
Other than that, method of identifying a cartridge, case or bullet, by engraving codes, has been around from a long time, the oldest patent dates back…to 1924.
Browsing the web, I have found that a company is specialized in bullets IDs called actually Bullet ID:
A fully integrated solution for ammunition inventory management.
Allows manufacturers full monitoring and tracking of the production line and supply chain.
Provides the ultimate inventory tool for law enforcement, allowing the traceability of a round from the point of manufacturing to the point of delivery.
The Bullet ID System gives authorized users, primarily police and military, the ability to use their smartphone to scan a bullet or shell-case imprinted with a unique laser-etched code. This allows for unprecedented inventory management at the level of the individual bullet.
They use state of the art laser and chip technology. The original owner could potentially be traced by a smartphone just by scanning a bullet or a case. To where it’s going to lead, knowing how simple it is to lose or steal ammunition?