Ammo & Guns Blog
Understanding M855 Ammunition Designations
Understanding M855 Ammunition Designations
M855 ammunition designations help identify a specific type of 5.56×45mm NATO cartridge used by the U.S. military and sold in some commercial ammunition markets. Understanding the M855 label, its relationship to SS109, and its common specifications makes it easier to interpret product packaging and compare ammunition descriptions accurately.
What Does M855 Mean?
M855 is a U.S. military cartridge designation for 5.56×45mm NATO ammunition. It is commonly associated with a 62-grain projectile featuring a steel penetrator within its construction.
The designation identifies a particular cartridge specification rather than a universal name for every 5.56 NATO round. Other 5.56 ammunition types may have different projectile designs, bullet weights, and performance characteristics.
When comparing products, check the manufacturer’s specifications and packaging instead of assuming that all 5.56 ammunition is equivalent.
What Is the Difference Between M855 and SS109?
M855 and SS109 are closely related designations, but they refer to different specification systems.
- M855: The U.S. military designation for a 5.56×45mm cartridge associated with a 62-grain projectile.
- SS109: A European-origin projectile designation commonly associated with a similar 62-grain design.
- Commercial equivalents: Some manufacturers use terms such as M855-style or SS109-style to describe ammunition with similar projectile characteristics. These labels do not automatically establish that two products are identical.
Manufacturing specifications, quality controls, and intended applications can differ between products. The exact cartridge designation and manufacturer’s documentation are the most reliable references.
Common M855 Ammunition Specifications
M855 ammunition is commonly described by several key characteristics.
- Cartridge: 5.56×45mm NATO
- Bullet weight: Typically 62 grains
- Projectile design: Commonly includes a steel penetrator and lead core beneath the jacket
- Visual identifier: Often features a green-painted bullet tip
- Designation: M855
These are general identifying characteristics, not a substitute for the specifications of an individual product. Commercial loads can vary, so verify the details on the box or manufacturer’s product page.
What Does the Green Tip Indicate?
The green-painted tip is commonly used to identify M855 ammunition. It provides a visual clue, but it should not be treated as definitive proof of the cartridge’s identity.
Tip colors are not universal across all manufacturers and ammunition types. Packaging information, cartridge markings where available, and official product specifications offer stronger confirmation.
Green tip ammunition is also sometimes described as armor-piercing. That description can be inaccurate or incomplete: the projectile’s steel penetrator affects its construction and behavior against certain materials, but legal classifications depend on the relevant law and technical definitions.
M855 vs. Standard Full Metal Jacket Ammunition
M855 and conventional full metal jacket (FMJ) ammunition may share the same 5.56×45mm cartridge dimensions, but their projectile designs can differ.
Standard FMJ bullets generally have a jacket surrounding a lead core. M855 typically incorporates a steel penetrator as part of its projectile construction. Conventional FMJ ammunition is available in multiple bullet weights, while M855 is commonly associated with a 62-grain projectile.
Neither the FMJ label nor the M855 designation alone provides every detail about a cartridge’s performance. Results depend on the specific load, firearm, barrel, and target material.
How to Read M855 Ammunition Labels
When reviewing M855 ammunition packaging, focus on these details:
- Cartridge designation: Confirm whether the box identifies the ammunition as 5.56×45mm NATO, M855, or another specification.
- Bullet weight: Check whether the listed projectile weight is 62 grains.
- Manufacturer information: Review the product description for projectile construction and intended use.
- Compatibility guidance: Follow the firearm manufacturer’s instructions and confirm the ammunition matches the firearm’s chamber markings.
- Local requirements: Check applicable laws governing ammunition purchase, possession, and transport.
Avoid identifying ammunition solely by bullet-tip color or assuming that similar labels guarantee identical specifications.
Final Thoughts
Understanding M855 ammunition designations helps distinguish this 5.56 NATO cartridge from other rifle ammunition. M855 is commonly associated with a 62-grain projectile and a green-painted tip, while SS109 refers to a related projectile designation. Because commercial products and specifications can vary, always confirm the cartridge label and manufacturer’s documentation before making comparisons or purchase decisions.
