Understanding the Differences: SS109 vs. M855 5.56 Ammo

Understanding the Differences: SS109 vs. M855 5.56 Ammo

Hey all, we here at True Shot Academy are going to talk about two closely related 5.56 loadings today. The SS109 and M855 represent NATO's standardized approach to intermediate rifle ammunition with enhanced penetration capabilities. Despite appearing identical to standard 5.56 ammunition, these loadings feature significant design differences that affect their performance and usability. Today we will explore what sets these specialized rounds apart and why those differences matter. Without further ado, let's examine these two steel-core ammunition types.

5.56mm NATO: A Brief History

The 5.56 cartridge emerged from development work in the late 1950s as the United States sought a lightweight, low-recoil alternative to the 7.62 NATO. Initially adopted as the .223 for the AR-15 platform, the cartridge underwent various modifications before standardization as the 5.56 in 1980. This lightweight cartridge enabled infantry to carry substantially more ammunition while maintaining reasonable effectiveness at typical combat distances. The original military loading, designated M193, featured a simple 55-grain full metal jacket bullet with a lead core. While effective against unarmored targets, this loading demonstrated limitations against hardened barriers and at extended ranges. These limitations became increasingly concerning as body armor proliferated among potential adversaries during the Cold War era. In response to these concerns, NATO initiated a program to develop an improved 5.56 loading with enhanced penetration capabilities, particularly against steel helmets at extended ranges. This initiative ultimately produced the SS109 loading, which would significantly influence 5.56 ammunition development across NATO forces.

SS109: The European NATO Standard

The SS109 cartridge emerged from Belgian ammunition manufacturer FN Herstal's development work in the late 1970s. Designed to meet NATO's enhanced performance requirements, particularly the ability to penetrate a standard steel helmet at 600 meters, the SS109 featured a significant departure from previous 5.56 projectile design with its partial steel core construction. Unlike the all-lead-core M193, the SS109 utilizes a 62-grain projectile with a composite core consisting of a lead base and a hardened steel penetrator in the forward section. This steel component, comprising approximately 40% of the core, significantly enhances the bullet's ability to defeat light barriers while improving ballistic performance at extended ranges. The projectile features a full metal copper jacket surrounding this dual-component core. The SS109 gained official NATO standardization in 1980, becoming the organization's standard rifle cartridge alongside FN's FNC rifle and the SS109 barrel with 1:7 twist rate. This standardization marked a significant shift from the previous 55-grain loadings, establishing the 62-grain steel penetrator design as NATO's preferred specification for member nations.

M855: America's Adoption of SS109

The United States military adopted the SS109 design as the M855 in 1982, essentially importing the Belgian design with minimal modifications to suit American production methods. This adoption aligned U.S. ammunition with NATO standardization efforts while addressing perceived shortcomings of the original M193 loading, particularly regarding barrier penetration and effective range. The M855 designation refers specifically to the American military's version of the SS109 specification. While functionally identical to SS109 in design concept and performance, the M855 designation indicates U.S. military production standards and quality control protocols. The cartridge can be identified by the distinctive green paint applied to the projectile tip, earning it the common nickname "green tip" among civilian shooters. This loading became the standard U.S. military 5.56 cartridge used with the M16A2 rifle and subsequent M4 carbine, both featuring the faster 1:7 barrel twist rate necessary to stabilize the longer 62-grain projectile. The M855 remains in widespread military use, though supplemented by enhanced versions like the M855A1 EPR (Enhanced Performance Round) developed to address certain performance limitations identified during combat operations. Purchase 5.56 Ammo

Physical and Design Similarities

Despite their different designations, SS109 and M855 share nearly identical physical characteristics and performance specifications. Both feature:

• 62-grain bullet weight
• Partial steel penetrator core with lead base
• Full metal copper jacket
• Overall length of approximately 2.26 inches
• Muzzle velocity of approximately 3,100 fps from a 20-inch barrel

These shared characteristics make SS109 and M855 functionally equivalent from a shooter's perspective. The different designations primarily reflect the ammunition's origin and production standards rather than any significant design or performance differences. In practical terms, military SS109 from European NATO sources and American M855 deliver essentially identical performance. Both loadings require a barrel twist rate of 1:9 or faster (with 1:7 being optimal) to properly stabilize the longer 62-grain projectile. Older rifles with slower 1:12 twist rates designed for 55-grain bullets may experience accuracy issues with these heavier projectiles due to inadequate stabilization. This compatibility consideration affects both SS109 and M855 equally.

Performance Characteristics

Both SS109 and M855 demonstrate similar ballistic performance, with muzzle velocities averaging 3,100 fps from 20-inch barrels and approximately 2,900 fps from 16-inch carbine barrels. This generates roughly 1,325 foot-pounds of energy at the muzzle, slightly more than the lighter M193 despite its lower velocity, due to the increased projectile mass. The steel penetrator component significantly enhances performance against certain barriers compared to all-lead-core designs. Both loadings effectively defeat mild steel barriers like vehicle bodies and can penetrate standard steel helmets at extended ranges (the original NATO requirement). This penetration capability represents the primary performance advantage over conventional lead-core ammunition. However, the steel penetrator design creates a performance trade-off. While barrier penetration improves, terminal effectiveness in soft tissue can actually decrease compared to the lighter, faster M193 loading. The M855/SS109 penetrates straight through soft tissue without significant yawing or fragmentation until it has traveled a considerable distance, sometimes resulting in less dramatic wound channels at close to moderate ranges compared to the older design.

Range Restrictions and Practical Limitations

The steel penetrator component that enhances military effectiveness creates significant restrictions for civilian use of both SS109 and M855 ammunition. Many indoor and public outdoor shooting ranges prohibit steel-core ammunition due to several practical concerns:

1. Backstop Damage: The steel penetrator can damage or prematurely wear out range backstops designed for lead-core ammunition, creating safety hazards and expensive repair requirements.
2. Fire Hazards: When striking steel targets or hard backstops, the steel component can create sparks capable of igniting dry vegetation or combustible materials near the impact area.
3. Ricochet Concerns: The steel penetrator increases ricochet potential when striking hard surfaces at shallow angles, potentially compromising range safety standards.

These restrictions significantly limit where civilian shooters can legally and safely use M855 or SS109 ammunition. Many commercial ranges explicitly ban "green tip" or any ammunition that fails a simple magnet test (used to detect steel components). These limitations make such ammunition impractical for many recreational shooters despite its widespread availability.

Legal and Regulatory Considerations

Beyond range restrictions, M855/SS109 ammunition has occasionally faced regulatory scrutiny in the United States. Most notably, in 2015, the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) proposed reclassifying M855 as "armor-piercing handgun ammunition" due to the growing popularity of AR-15 pistols chambered in 5.56mm. This reclassification would have effectively banned its importation and manufacture for civilian markets. While this specific proposal was withdrawn following significant public opposition, it highlights the regulatory uncertainty sometimes surrounding steel-core ammunition. Various states and municipalities have implemented their own restrictions on steel-core or "armor-piercing" ammunition, creating a complex legal landscape for users of M855/SS109. International regulations vary significantly, with many countries restricting civilian access to any ammunition with steel penetrator components. These international restrictions affect both SS109 and M855 equally, limiting their availability to military and law enforcement agencies in many regions. Purchase 5.56 Ammo

Commercial Availability and Manufacturers

Despite various restrictions, commercial versions of M855/SS109 ammunition remain widely available in the United States civilian market. Major manufacturers producing this ammunition type include:

1. Federal: Produces XM855 (the "X" denoting commercial rather than military specification) in various packaging options from individual boxes to bulk packs.
2. Winchester: Offers their "Green Tip" 5.56 ammunition following the M855 specification in both individual boxes and bulk quantities.
3. PMC: Manufactures X-TAC “Green Tip” 5.56 ammunition to the M855 specification with identical performance characteristics to military versions.
4. Lake City: The U.S. military's primary ammunition plant occasionally releases overrun M855 production to the civilian market through various distributors.
5. IMI (Israel Military Industries): Produces SS109-type ammunition to NATO specifications, available through various importers.
6. Prvi Partizan (PPU): Serbian manufacturer offering SS109-compliant ammunition for export markets including the United States.

These commercial offerings typically meet or exceed military specifications while being packaged and marketed for civilian sales. Pricing generally exceeds standard 55-grain FMJ ammunition due to the more complex projectile construction and enhanced performance capabilities.

Practical Applications

Despite range restrictions, M855/SS109 ammunition serves several practical purposes for civilian shooters with access to appropriate facilities:

1. Training Consistency: Military veterans and law enforcement often prefer training with the same ammunition type used in their professional capacities. Additionally, as NATO spec loadings, ammunition of either type is consistently loaded to meet or exceed high standards.
2. Barrier Penetration: The enhanced barrier penetration provides practical advantages in certain hunting or defensive scenarios involving light obstacles.
3. Reduced Wind Drift: The heavier 62-grain projectile demonstrates improved resistance to wind deflection compared to lighter 55-grain bullets, beneficial for longer-range shooting.
4. Collection Value: Some firearm collectors and enthusiasts value military-specification ammunition for historical authenticity when paired with military firearms.

However, for most civilian shooting applications including target practice, competition, and even most defensive scenarios, non-steel-core alternatives often provide better overall performance with fewer restrictions. Modern expanding ammunition designs typically deliver superior terminal performance compared to M855/SS109 in defensive applications.

Conclusion

The SS109 and M855 represent essentially identical ammunition types developed to enhance NATO's 5.56 capabilities through partial steel-core construction. Despite different designations reflecting their European and American origins respectively, these loadings deliver virtually identical performance characteristics, with enhanced barrier penetration at the cost of certain range restrictions and potential regulatory complications. For military applications, the steel penetrator component provides valuable capabilities against hardened targets. For civilian users, however, the practical limitations often outweigh the performance advantages, particularly given the range restrictions that significantly limit where such ammunition can be legally and safely used. These limitations have encouraged the development of lead-core alternatives that provide similar ballistic performance without the steel component restrictions. All in all, understanding the similarities, differences, and limitations of SS109 and M855 ammunition helps shooters make informed decisions based on their specific needs and shooting environments. We here at True Shot Ammo carry both conventional 5.56 loadings and M855/SS109 ammunition in addition to our extensive inventory of ammo for sale. Our selection of ammunition for sale encompasses popular calibers and gauges like 9mm, 5.56, 12 gauge, and .22 LR. Whether you want to buy bulk 5.56 ammunition of various types or buy bulk ammo, we have got you covered. As always, happy shooting.