M193 vs. M855: Which 5.56 Round Should You Stockpile? (2026)

First Shots: M193 vs M855

You’ve already decided which rifle to purchase. Now you need to know which 5.56 ammo to feed it: M193, or M855 (aka “green tip”) ammo.

The M193 vs. M855 debate boils down to these points. M193 ammo is the better choice to buy in bulk, as it is less expensive and offers solid performance out to 500 yards. M855 green tip ammo offers better penetration and is slightly more accurate at longer distances. The M855 bullet also contains steel and is therefore prohibited at many commercial gun ranges.

If you’re ready to load your mags with either of these amazing 5.56 cartridges, make sure to check out our bulk 5.56 ammo offerings. Otherwise, keep reading to learn why M193 ammo is my preferred choice.

Key Differences Between M855 and M193

M193 Ammo History

The M193 cartridge was developed in the early 1960s. It was formally adopted by the U.S. military for its new M16 rifle in 1964.

Initially developed as the 223 Remington, the new military cartridge was designed to fire a 55 grain full metal jacket boat tail projectile at a muzzle velocity of 3,250 fps and generate maximum chamber pressure of 55,000 psi.

The 223 Rem round was designated “Cartridge, 5.56mm ball, M193″ upon its adoption in 1964.

The M193 saw its first action in the jungles of Vietnam. It remained our frontline battle cartridge until the late 1980s, when the military switched to M855 ammo (more on that in a moment).

The M193 cartridge is sealed at its case mouth and primer pocket for improved moisture resistance. The primer pocket is also metallically crimped in place to prevent primers from backing out (and potentially striking the shooter’s eye) during automatic fire.

Early M16s had a relatively slow 1:12 barrel twist rate, which stabilizes a 55 grain bullet extremely well. In general, the M193 round is stabilized effectively in barrels ranging between a 1:9 to 1:12 twist rate, and reaches its full muzzle velocity potential from a 20” barrel.

For the story of the man who designed the rifle this cartridge was built around, read our history of Eugene Stoner, creator of the AR-15.

M193 Specs

One of the major benefits of the 55 grain projectile is its propensity to yaw and fragment when it encounters soft tissue. The bullet fragments inflict serious trauma whilst simultaneously mitigating the risk of over-penetration.

However, there are some downsides to the M193.

Bullet fragmentation was not always observed on the battlefield, with many soldiers reporting their bullets merely passing through enemy combatants. This presented a serious issue, as the M193 round’s narrow projectile’s terminal performance is significantly less injurious without fragmentation.

Another issue was the bullet’s tendency to deflect when it encountered barriers like thick clothing or vegetation (I hear there’s a lot of the latter in Vietnam). Overall, M193 is not very effective at penetrating barriers and is ineffective against modern body armor. This wouldn’t have been a major problem while fighting unarmored Viet Cong soldiers, but modern militaries issue ballistic plates and helmets which the M193 is ill-equipped to handle.

This is where the M855 comes in.

M855 Ammo History

Tensions were high between the USSR and United States/NATO following the Second World War. Conflict seemed inevitable, which led the NATO alliance to sign a treaty replacing the 7.62x51mm (308 Winchester) with a smaller, lower-recoil cartridge in 1970.

FN Herstal took up the task of creating a new round, using the M193 as a starting point. What they developed came to be known as “M855” to the U.S., and “SS109” to other NATO members.

Often referred to as “green tip” ammo, M855 bullets have bimetal cores: lead in back, steel in front. Their jacketed tips are painted green to facilitate identification.

M855 ammo has been NATO and the U.S. military’s primary intermediate combat cartridge since 1980. On paper, M855 seems like a massive upgrade over M193. However, battlefield reports from the First Gulf War and Somalia paint a different picture.

Soldiers on the front lines often reported M855 ammo being ineffective against enemy soldiers. This has been mostly attributed to the M855’s inability to fragment when it impacts soft targets.

Although the M855 bullet’s steel “penetrator” tip promotes more effective penetration through barriers, it was discovered that the bullet often passes straight through its target, inflicting a narrow wound channel as a result. Soldiers reported enemy combatants taking multiple shots of M855 and still not going down.

Those lackluster terminal ballistics sparked the development of a variety of new AR-15 cartridges during the early 2000s. The most successful of them gets a head-to-head treatment in our 300 Blackout vs 5.56 comparison.

Green Tip Ammo Specs

The M855 round fires a 62 grain FMJ boat-tail projectile with a soft lead core and a 7 grain mild steel penetrator tip. Its muzzle velocity is slightly north of 3,000 fps, and it has a maximum chamber pressure of 62,366 psi (430 MPa).

The primer pockets and case mouths of M855 ammo are sealed, just as with M193 ammo.

The M855 bullet’s hard steel tip increases its barrier potential for barrier penetration. The bullet also increases the M855 round’s long-range capabilities – and not just because it is heavier.

The steel penetrator tip is designed to punch through a 0.135″ mild steel plate at 500 yards (chosen to mimic Soviet-era ballistic helmets). Placement of the steel core also shifted the bullet’s center of gravity toward its rear, thus improving in-flight stability and the potential for the tip to impact targets at longer ranges.

Its steel tip increases the bullet’s length and therefore its ballistic coefficient. This also makes the M855 slightly more accurate at longer ranges. Note that faster twist rate barrels are needed to stabilize these longer, heavier bullets. A 1:7″ twist rate is typically preferred for M855 ammo.

Can Civilians Own Mil-Spec M855 and M193 Ammo?

Shooters often ask if they can own or purchase mil-spec ammo. The answer is “Kind of.”

As I’m sure you can imagine, there are some strict rules around what types of military ammo civilians can own and use.

However, this doesn’t mean civilians can’t get their hands on nearly identical ammo to what the military uses.

The Lake City Army Ammunition Plant often releases surplus ammo to the civilian market that was made on the same assembly lines as the military stuff. Federal also has its own version of M193, which it markets under its American Eagle label as “XM193.” (The “X” prefix merely designates that it was made for civilian use.)

To further complicate matters, some manufacturers (like PMC) often sell 5.56 ammo under the M193 and M855 designations, though it is not technically mil-spec.

M855 vs M193 Ballistics

One of the benefits of M855 ammo is its enhanced long-range shooting capabilities. But is the M855 really all that superior to the M193 in terms of ballistics? Let’s take a look!

In the following ballistics table we compare M855 vs M193 ballistics fired from a 20″ barrel out to 700 yards.

Read the full comparison here: https://ammo.com/comparison/m193-vs-m855

Source: https://freedombunker.com/2026/08/08/m193-vs-m855/