M193 vs M855: What’s the Difference?
M193 vs M855 is one of the most common comparisons when discussing 5.56 NATO ammunition. Both are military 5.56×45mm ball cartridges, but they use different projectiles and were developed for different rifle configurations and performance requirements.
M193 uses a 55-grain full-metal-jacket projectile, while M855 uses a 62-grain projectile with a steel penetrator. The heavier and longer M855 projectile also influenced the move toward faster barrel twist rates in later M16 rifles.
M193 vs M855 at a Glance
| Feature | M193 | M855 |
|---|---|---|
| Cartridge | 5.56×45mm | 5.56×45mm |
| Projectile weight | 55 grains | 62 grains |
| Projectile construction | Gilding-metal jacket with lead-alloy core | Gilding-metal jacket, lead-alloy core and steel penetrator |
| Common identification | Plain/unpainted tip | Green tip |
| Original military association | M16A1 | M16A2/M4 |
| Typical historical twist | 1:12 | 1:7 |
| Primary design emphasis | Lightweight ball ammunition | Improved penetration and longer-range performance |
| Tracer counterpart | M196 | M856 |
The U.S. Army’s M16/M4 technical documentation identifies M193 as a 55-grain ball cartridge and M855 as a 62-grain ball cartridge incorporating a steel penetrator.
What Is M193?
M193 is the original U.S. military 5.56mm ball cartridge associated with the M16A1.
The M193 projectile weighs 55 grains and uses a gilding-metal jacket around a lead-alloy core. Army documentation identifies it as the standard field cartridge for the M16A1.
Its relatively light projectile was designed around the M16A1’s 1:12 rifling twist. That twist was well suited to the original M193 projectile.
M193 is still manufactured today, although it was eventually supplemented in U.S. service by the heavier M855 cartridge. The Army notes that M193 continues to be produced, including for foreign military sales.
What Is M855?
M855 is the 62-grain 5.56mm ball cartridge commonly recognized by its green projectile tip.
Unlike M193, the M855 projectile incorporates a steel penetrator ahead of its lead-alloy core. The Army adopted M855 in the early 1980s as an improvement over M193, with the heavier projectile and penetrator intended to provide better performance against harder targets.
The M855 projectile is also longer than M193. That difference is important because projectile length, not simply weight, influences the amount of rifling spin needed for stabilization.
Why Was M855 Developed?
The transition from M193 to M855 was driven partly by the desire for improved performance at longer distances and against harder targets.
The Army states that M855 was adopted in 1982 to replace M193 and improve performance at longer ranges with the M249 Squad Automatic Weapon. The steel penetrator was intended to provide increased hard-target performance.
The introduction of M855 was accompanied by changes to the rifle platform. The M16A2 adopted a 1:7 twist, allowing it to stabilize the longer M855 projectile while remaining capable of firing M193.
M193 vs M855 Bullet Weight
The most obvious difference is projectile weight.
- M193: 55 grains
- M855: 62 grains
A grain is a unit of mass commonly used for projectile and ammunition specifications. The seven-grain difference may sound small, but projectile weight is only part of the equation.
The M855 projectile is also longer and has a different internal construction. Army technical documentation specifically notes that the differences in projectile dimensions and configuration affect the twist required for stabilization.
This is why it is misleading to say that M855 is simply “M193 but heavier.”
M193 vs M855 Projectile Construction
Projectile construction is one of the most important differences.
M193 Construction
M193 uses a 55-grain gilding-metal-jacketed, lead-alloy-core projectile. It does not contain the steel penetrator found in M855.
M855 Construction
M855 uses a 62-grain gilding-metal-jacketed projectile with a steel penetrator and lead-alloy core.
The steel penetrator changes the projectile’s construction and its intended hard-target performance.
However, the presence of a steel penetrator should not automatically be interpreted as meaning that every M855 cartridge is armor-piercing ammunition. M855 is commonly classified as a ball cartridge rather than a dedicated armor-piercing cartridge.
M193 vs M855 Twist Rate
Twist rate is particularly important when comparing these two cartridges.
The original M16A1 used a 1:12 twist, meaning the rifling makes one complete rotation every 12 inches. The M16A2 and later M16/M4 configurations moved to a 1:7 twist to stabilize the longer M855 projectile.
Army documentation specifically states that the M16A1’s 1:12 twist did not provide sufficient stabilization for M855, resulting in erratic performance and inaccuracy.
This illustrates an important principle:
Projectile length and construction can matter more to stabilization than bullet weight alone.
A modern rifle with an appropriate faster twist can generally accommodate a broader range of 5.56 projectile designs than the original 1:12-twist M16A1.
Is M193 Faster Than M855?
Generally, M193 has a higher muzzle velocity than M855 when comparing representative military-specification loads from appropriate test conditions.
The primary reason is that M193 uses a lighter projectile. A heavier projectile requires more propellant energy to achieve the same velocity, all else being equal.
However, there is no single universal velocity number for every M193 or M855 load. Commercial ammunition can differ in powder charge, projectile construction, pressure characteristics, barrel length, and test conditions.
For that reason, ammunition-specific manufacturer data is more useful than assuming that every M193 or M855 cartridge produces the same velocity.
M193 vs M855 Ballistics
The ballistic differences between M193 and M855 extend beyond muzzle velocity.
M193
The lighter 55-grain projectile can achieve higher velocity in comparable load configurations. Its performance is closely associated with the original M16A1 and its 1:12 twist.
M855
The heavier 62-grain projectile generally leaves the muzzle at a lower velocity than a comparable 55-grain load, but its projectile design provides different external-ballistic and hard-target characteristics.
The heavier M855 projectile can also retain velocity differently as distance increases, depending on its ballistic coefficient and the conditions of the comparison.
Historical Army testing found that M193 and M855 could have comparable accuracy at shorter distances under certain rifle configurations, while M855’s heavier projectile and the faster twist of the M16A2 could provide advantages at longer distances.
M193 vs M855 Accuracy
Neither cartridge is universally “more accurate.”
Accuracy depends on the ammunition, rifle, barrel, twist rate, manufacturing consistency, environmental conditions, and other variables.
The rifle’s twist rate is particularly important. Army testing found that M193 fired from the M16A2 produced accuracy comparable to M855 out to 400 yards in the tested conditions. At longer distances, the combination of M855’s heavier projectile and the M16A2’s faster 1:7 twist could provide advantages.
The same testing also demonstrated why M855 was not ideally matched to the older M16A1’s 1:12 twist.
Therefore, it is better to ask whether a particular projectile is appropriately stabilized by a particular barrel rather than assuming one cartridge is inherently more accurate.
M193 vs M855 Velocity and Energy
M193’s lighter projectile generally produces higher muzzle velocity in comparable loads.
M855’s heavier projectile can produce different muzzle-energy and downrange characteristics despite its lower initial velocity.
Muzzle energy is affected by both mass and velocity, with velocity having a squared relationship to kinetic energy. Consequently, a small velocity difference can have a meaningful effect on calculated muzzle energy.
But ballistic performance should be evaluated using the actual ammunition’s published data rather than assuming that the heavier projectile automatically produces more energy at every distance.
M193 vs M855 Trajectory
M193’s higher velocity can provide a flatter initial trajectory under comparable conditions.
M855, however, uses a heavier projectile with different aerodynamic characteristics. As distance increases, retained velocity and ballistic coefficient become increasingly important.
Therefore, a simple statement such as “M193 shoots flatter” does not tell the entire story. A meaningful trajectory comparison needs to specify:
- Bullet weight
- Projectile design
- Muzzle velocity
- Ballistic coefficient
- Barrel length
- Zero distance
- Sight height
- Atmospheric conditions
M193 vs M855 and Barrel Twist
Barrel twist is one of the clearest differences in how the two cartridges were originally intended to be used.
The M16A1’s 1:12 twist was designed around the shorter M193 projectile. The later M16A2’s 1:7 twist was selected to stabilize the longer M855 projectile.
This doesn’t mean that 1:7 barrels can only shoot M855 or that 1:12 barrels can only shoot M193. The important consideration is whether the projectile is adequately stabilized by the particular barrel.
Modern 5.56 rifles may use a variety of twist rates, so the firearm manufacturer’s specifications should be checked before selecting ammunition.
M193 vs M855 Green Tip
One of the easiest ways to distinguish the two military loads visually is the projectile tip.
M193: generally has a plain/unpainted projectile tip.
M855: is commonly identified by its green-painted tip.
The green tip is associated with M855’s projectile design and should not be interpreted as a universal indicator that any green-tipped commercial cartridge is exactly the same as military M855.
Commercial manufacturers may use different projectile designs, specifications, and markings.
M193 vs M855: Are They the Same Caliber?
Yes.
Both are 5.56×45mm cartridges.
The important differences are in the projectile design, weight, construction, ballistic characteristics, and historical military specifications.
This is also why M193 and M855 should not be confused with completely different cartridge families simply because their bullet weights differ.
M193 vs M855 and 5.56 NATO
M193 and M855 are both associated with the 5.56×45mm military ammunition family, but their specifications and historical roles differ.
M193 predates NATO standardization of the later 62-grain SS109/M855 configuration. M855 became the U.S. military’s 62-grain standard ball cartridge and was associated with the M16A2, M4 and M249 platforms.
The broader distinction between .223 Remington and 5.56 NATO chambers should also be kept separate from the M193-versus-M855 comparison. Cartridge compatibility depends on the firearm’s chamber specifications, not simply on whether the ammunition is 55 or 62 grains.
M193 vs M855: Which Has Better Long-Range Performance?
M855 was specifically developed to improve performance at longer ranges compared with M193, and its heavier projectile works with the faster twist adopted for later M16 rifles.
However, “better” depends on what characteristic is being measured.
M193 and M855 differ in:
- Projectile weight
- Projectile length
- Projectile construction
- Muzzle velocity
- Ballistic coefficient
- Stabilization requirements
- Intended military application
A particular modern 5.56 load can also outperform either traditional military load in some aspect because commercial ammunition includes many projectile designs that were not available when M193 and M855 were developed.
M193 vs M855 vs M855A1
M855 should also be distinguished from M855A1.
M855A1 is a later Army Enhanced Performance Round developed to replace M855. The Army began shipping M855A1 in 2010, describing improvements including hard-target capability, consistency, accuracy, muzzle flash reduction and velocity.
M855A1 retains a 62-grain projectile weight but uses a substantially different projectile construction, including a copper-based design and exposed hardened-steel penetrator.
Therefore:
| Cartridge | Projectile | Historical role |
|---|---|---|
| M193 | 55-grain lead-core FMJ | Original 5.56 military ball load |
| M855 | 62-grain projectile with steel penetrator | Later standard ball load |
| M855A1 | 62-grain enhanced-performance projectile | Successor to M855 in U.S. Army service |
M855A1 should not simply be treated as another name for M855.
Common Misconceptions About M193 and M855
M855 Is Just Heavier M193
Not quite.
M855 is heavier, but its projectile also has a different construction and is longer. The steel penetrator is a defining feature of the M855 projectile.
Every 55-Grain 5.56 Round Is M193
No.
M193 is a specific military ammunition specification. Commercial manufacturers produce many different 55-grain 5.56 and .223 loads with different projectiles and ballistic characteristics.
Every 62-Grain 5.56 Round Is M855
No.
A 62-grain projectile does not automatically make ammunition M855. Commercial 62-grain loads can use different projectile constructions.
Green Tip Always Means Armor Piercing
No.
The green tip is commonly associated with M855, but M855 is a ball cartridge with a steel penetrator rather than simply being synonymous with armor-piercing ammunition.
M855 Is Always More Accurate
No.
Accuracy depends on the ammunition and firearm combination. Historical Army testing found comparable M193 and M855 accuracy under certain conditions, while twist rate became particularly important when firing M855 from the older M16A1.
Frequently Asked Questions
What is the main difference between M193 and M855?
M193 is a 55-grain military 5.56mm ball cartridge with a lead-alloy core, while M855 is a 62-grain ball cartridge incorporating a steel penetrator. M855’s longer projectile also led to the adoption of faster rifling twists in later M16 rifles.
Is M193 55 grain?
Yes. U.S. Army documentation identifies M193 as a 55-grain cartridge.
Is M855 62 grain?
Yes. M855 uses a 62-grain projectile with a steel penetrator.
Which is faster, M193 or M855?
M193 generally has the higher muzzle velocity when comparable military-style loads are fired under similar conditions because it uses the lighter projectile. Actual velocity depends on the specific ammunition and barrel.
Does M855 need a 1:7 twist?
M855 was designed around the faster twist used by the M16A2 and later platforms. Army documentation explains that the older M16A1’s 1:12 twist was insufficient to reliably stabilize the longer M855 projectile.
Can a 1:7 twist fire M193?
The M16A2’s 1:7 twist was capable of firing M193 as well as M855.
Is M193 better than M855?
Neither is universally better. M193 is lighter and generally faster, while M855 has a heavier projectile and steel penetrator and was developed for improved performance at longer ranges and against harder targets.
Is M855 the same as M855A1?
No. M855A1 is a later enhanced-performance 62-grain cartridge with substantially different projectile construction. The Army began replacing M855 with M855A1 in 2010.
Bottom Line
M193 vs M855 comes down to more than 55 grains versus 62 grains.
M193 is the original 55-grain 5.56mm military ball cartridge associated with the M16A1 and its 1:12 twist. M855 is the later 62-grain ball cartridge featuring a steel penetrator and a longer projectile, developed alongside the faster 1:7 twist used in the M16A2 and subsequent platforms.
M193 generally offers higher velocity with its lighter projectile, while M855 was designed to provide different ballistic and hard-target characteristics. Neither should be judged solely by bullet weight: projectile construction, length, ballistic coefficient, velocity, and barrel twist all contribute to real-world performance.
Most importantly, M193 and M855 are specific ammunition designs, not generic names for every 55-grain or 62-grain 5.56 cartridge.