M193 vs M855 5.56: What's the Difference?

M193 vs M855 5.56: What's the Difference?

Hey all, we here at True Shot Academy are going to talk about two of the most common 5.56 loadings today. The M193 and M855 (often called "green tip") represent different approaches to military rifle ammunition that have found their way into civilian shooting applications. Despite sharing the same caliber, these loadings feature significant differences that affect their performance and appropriate use cases. Today we will explore what sets these 5.56 loads apart and why those differences matter. Without further ado, let's examine these two influential ammunition types.

Understanding 5.56mm NATO

Before diving into the specific loadings, it's worth understanding what 5.56 actually is. Developed in the late 1950s alongside the AR-15/M16 platform, 5.56 emerged as a high-velocity, intermediate rifle cartridge designed to provide infantry with a lightweight, low-recoil alternative to the 7.62x51mm NATO. The cartridge features a bottleneck design with a case length of 45mm and an overall length of 57.4mm. While dimensionally similar to the civilian .223, 5.56 ammunition operates at higher pressures and features different throat dimensions. Modern firearms with 5.56 chambers can safely fire both 5.56 and .223 ammunition, though the reverse isn't always true. This distinction becomes particularly important when discussing specific military loadings like M193 and M855. The 5.56 cartridge has become one of the world's most common rifle calibers, serving as the standard service cartridge for NATO forces and finding widespread adoption in civilian sporting rifles. The cartridge's lightweight nature allows soldiers and civilian shooters to carry substantial ammunition loads while maintaining reasonable control during rapid fire sequences.

M193 Ammunition: The Original Loading

M193 represents the original standardized 5.56 loading adopted by the U.S. military in 1964 alongside the M16 rifle. This ammunition features a 55-grain full metal jacket bullet with a lead core completely enclosed in a copper jacket (sometimes called a "ball" round in military terminology). The projectile has no steel components and features a simple boat-tail design for improved aerodynamics. The M193 loading typically achieves velocities around 3,250 feet per second from a 20-inch barrel, generating approximately 1,290 foot-pounds of energy at the muzzle. This high velocity contributed to the round's infamous terminal performance in early Vietnam-era combat, where the bullet would often yaw and fragment upon striking tissue, creating devastating wound channels despite its small size. The high velocity and all-copper/lead construction give M193 specific performance characteristics. The round performs well against unarmored targets and soft barriers but shows limited effectiveness against harder barriers like steel or ceramic armor plates. The 55-grain bullet sheds velocity relatively quickly compared to heavier projectiles, reducing its effective range for precision applications beyond 300-400 yards.

M855 Ammunition: The "Green Tip" Evolution

M855 emerged in the 1980s as part of NATO ammunition standardization efforts. Adopted officially in 1982, this loading features a 62-grain projectile with a notable design difference from its predecessor: a partial steel core. The bullet construction includes a lead base with a steel penetrator tip comprising approximately 40% of the core, all enclosed in a copper jacket. The cartridge takes its "green tip" nickname from the distinctive green paint applied to the projectile tip for identification. From a 20-inch barrel, M855 typically achieves velocities around 3,100 feet per second, generating approximately 1,325 foot-pounds of energy at the muzzle. The slightly reduced velocity compared to M193 is offset by the increased mass and sectional density of the heavier bullet, resulting in better retention of energy at distance and improved resistance to wind deflection. The steel penetrator component was designed specifically to improve performance against hardened targets and extend effective range. This design feature gives M855 better barrier penetration capabilities, particularly against steel helmets and body armor—a direct response to Warsaw Pact body armor capabilities that concerned NATO planners during the Cold War. Purchase 5.56 Ammo

Ballistic Performance Differences

Trajectory differences between these loadings become apparent at extended ranges. The M855's heavier bullet maintains momentum better, resulting in less drop at distances beyond 300 yards. At 500 yards, M855 typically drops approximately 4-6 inches less than M193 from the same barrel length. This flatter trajectory makes M855 somewhat easier to use in applications requiring longer-range engagement. Wind drift also favors the heavier M855 loading. The 62-grain bullet's higher ballistic coefficient (approximately .304 compared to M193's .243) provides greater resistance to crosswind deflection. In a 10 mph crosswind at 500 yards, M855 might drift 5-7 inches less than M193, a significant advantage for precision shooting in variable conditions. Terminal performance differences create the most significant practical distinction between these loadings. The M193's higher velocity actually gives it superior fragmentation effects in soft tissue at close to moderate ranges. Somewhat counterintuitively, the lighter M193 often creates more dramatic wound channels at typical engagement distances than the "improved" M855, which tends to over-penetrate without yawing or fragmenting until it sheds sufficient velocity.

Armor and Barrier Penetration

The M855's partial steel core gives it superior performance against certain barriers. The steel penetrator allows the round to defeat mild steel plates, automobile bodies, and similar barriers more effectively than the all-lead-core M193. This penetration capability was a primary design consideration when the round was developed as a replacement for the original loading. However, in an interesting ballistic quirk, M193 actually outperforms M855 against certain types of steel armor when fired from longer barrels. The extremely high velocity of M193 from a 20-inch barrel can defeat some steel armor plates through sheer kinetic energy, essentially overwhelming the plate's resistance through velocity rather than penetrator design. This phenomenon diminishes significantly with shorter barrels that generate lower velocities. Against modern ceramic composite armor, neither loading proves particularly effective, as these protection systems have evolved specifically to defeat standard rifle threats. Both rounds will typically be stopped by Level III or greater body armor, though the M855 presents a somewhat greater threat to older armor designs due to its penetrator component.

Range Restrictions and Legal Considerations

The M855's steel penetrator component has created significant range restrictions for this ammunition type. Many indoor and outdoor public shooting ranges prohibit its use due to concerns about damage to backstops, increased fire hazards from sparks when striking steel, and potential ricochets. Range staff frequently check ammunition with magnets to detect the steel components in M855 projectiles. M193, by contrast, faces few restrictions at commercial ranges. Its all-copper/lead construction behaves similarly to standard commercial .223 ammo when impacting backstops, presenting no unusual hazards to range facilities. This broader acceptance makes M193 a more versatile option for shooters who frequent public ranges rather than private land. Legal restrictions occasionally target M855 specifically due to its "armor-piercing" capability. Most notably, in 2015, the ATF proposed reclassifying M855 as armor-piercing handgun ammunition due to the existence of AR-15 pistols chambered in 5.56, which would have effectively banned its importation and manufacture for civilian use. While this proposal was ultimately withdrawn following public opposition, it highlights the ongoing regulatory scrutiny this ammunition sometimes faces.

Who Makes M193 and M855 Ammunition

Military contract M193 and M855 ammunition comes from government facilities like Lake City Army Ammunition Plant (operated by Winchester) and approved contractors meeting military specifications. This ammunition often reaches the civilian market through surplus sales or commercial loadings produced on the same lines as military contract ammunition. Commercial manufacturers like PMC produce abundant quantities of both loading types. Companies like Federal also offer variants of these loadings labeled as "XM193" and "XM855" to denote their departure from military specifications. These loadings generally perform similarly to their military counterparts while sometimes offering improved consistency for civilian applications. Other manufacturers like Wolf produce steel-cased offerings which emulate these types of loadings, though typically with different bullet constructions. These alternatives offer cost-effective training options but may not precisely replicate the terminal ballistics of brass-cased equivalents due to velocity differences and modified bullet construction necessitated by manufacturing limitations. Purchase 5.56 Ammo

Practical Applications and Use Cases

For general-purpose AR-15 use, M193 often represents the more practical option for most civilian shooters. Its widespread range acceptance, good terminal performance at common engagement distances, and typically lower cost make it suitable for training, competition, and defensive applications. The lighter recoil impulse can also benefit shooters during high-volume sessions or rapid-fire scenarios. M855 finds its niche in specific applications requiring barrier penetration or extended range performance. The loading's ability to defeat certain barriers makes it potentially valuable for some defensive scenarios involving cover or intermediate obstacles. The improved ballistic coefficient and retained energy also benefit those engaging targets beyond 300 yards where trajectory advantages become more pronounced. For hunting applications, neither loading represents an ideal choice for medium game, though M855's better weight retention and penetration can provide some advantage. Purpose-designed hunting loads with controlled expansion bullets typically offer superior terminal performance on game animals compared to either military-derived loading.

Conclusion

M193 and M855 represent different approaches to military 5.56 ammunition that have found their way into civilian shooting applications. The lighter, faster M193 offers excellent terminal performance at moderate ranges, broader range acceptance, and typically lower cost. The heavier M855 with its partial steel core provides better barrier penetration, slightly flatter trajectory at distance, and improved resistance to wind deflection. For most civilian shooters, M193 proves more practical for regular use due to fewer restrictions and similar or superior performance in common applications. M855 serves well in specific scenarios where its barrier penetration or slightly enhanced long-range performance justifies the additional cost and potential range limitations. Understanding these differences allows shooters to select the appropriate loading based on their specific needs rather than assumptions about which represents a "better" option. All in all, both M193 and M855 continue to serve shooters effectively across various applications, with each offering distinct advantages in specific scenarios. We here at True Shot Ammo carry both M193 and M855 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 either type or purchase bulk ammo we have got you covered. As always, happy shooting.