Ace the Officer FMF 101-119 Challenge 2026 – Conquer Your Future with Confidence!

In military ammunition designations, the number after M identifies a specific cartridge and projectile type. M855 is the standard ball round for the 5.56x45mm cartridge—regular, non-tracer ammunition used for general service and training. It’s designed to provide dependable performance with a full metal jacket and, in this case, a steel penetrator to improve barrier penetration.

The other designations in the set correspond to different special-purpose rounds (such as tracer or training/dummy rounds), which is why they aren’t described as the standard ball type.