To clarify, many different types of ammunition have bullets with green tips. In this article we aren’t talking about polymer tipped bullets, which can have tips of any color. We are talking about 5.56x45mm M855, which is commonly referred to as “green tip” ammo. Its bullet’s tip is not made of polymer – it is merely painted green for easy identification.
What Is M855 Ammunition?
Think of the U.S. Armed Forces’ 5.56x45mm M193 spec cartridge as the standard. It is loaded with a 55 grain full metal jacket (FMJ) projectile, which is comprised of an alloyed lead core and copper alloy jacket. It was designated in 1963, and currently serves as the standard issue ammo for training and field use with the M4 carbine.
The M193 bullet exhibited a shortcoming, however. It frequently failed to penetrate helmets – and you really do want your army’s bullets to penetrate helmets. That’s why the U.S. Armed Forces adopted the M855 cartridge in 1980. (NATO also adopted it, but they named it “SS109” and did not bother giving its bullet green paint. Australia, which is a NATO Enhanced Opportunity Partner, has their own version called “F1” which also lacks paint.)
Like any other normal FMJ, the M855 bullet wears a hard copper alloy jacket that promotes smooth feeding in a semi-automatic firearm. The M855 bullet’s core is what makes it special, as it is comprised of two separate pieces: a seven grain steel “penetrator” tip in the front, and normal alloyed lead in the back. Furthermore, instead of 55 grains, the M855 projectile weighs 62 grains. Its greater mass gives it greater momentum, which helps it (A) resist wind deflection in flight, and (B) penetrate deeper into its target.
What Makes M855 Ammunition Different?
The M855 bullet’s hard steel front section is effective. It enables the projectile to pierce a 3mm (~0.12”) thick sheet of steel at ranges of up to 600 meters (~656 yards). According to Nammo, the M855 projectile can also penetrate up to 12mm (~0.47) of rolled homogeneous armor (RHA) at a range of 100 meters (~109 yards). The M855 projectile also offers different terminal ballistics than the M193.
The M193 bullet has a tendency to fragment if it strikes soft tissue at a velocity of 2,700 feet per second (fps) or higher. The M855 is less likely to exhibit the same degree of fragmentation, which has earned it the reputation as being more “humanitarian.” However, the M855 bullet is disposed to yaw as it penetrates soft tissue following high-velocity impact; afterward, its two core sections are likely to break apart. The result is two individual wound channels.
As mentioned earlier, the M855 projectile’s heftier 62 grain weight also affects its ballistic performance. It is designed to be fired through a 20” barrel with a 1:9” rate of twist.* Under these circumstances the projectile reliably achieves a muzzle velocity of 3,020 fps (with reasonable variation). At that rate the M855 bullet exhibits a G1 ballistic coefficient of 0.307. Compare those data to those of the M193 projectile, which clears a 20” barrel at a velocity of approximately 3,165 fps and exhibits a G1 ballistic coefficient of 0.246, and you can start making inferences about the two rounds’ ballistic performance.
If you fire an M855 cartridge at a 200-yard zero with a rifle that has 1.5” high sights, then you can anticipate -7.56” drop at 300 yards and supersonic velocity until ~825 yards. If you fire an M193 cartridge under the same conditions, then you can anticipate -7.53” drop at 300 yards and supersonic velocity until ~700 yards. In fewer words, the M855’s higher mass enables it to conserve its momentum more efficiently. In addition to warding off wind deflection, that helps the bullet remain supersonic over farther distances. This is important to long-distance accuracy, because a bullet undergoes “transonic destabilization” and begins to wobble when its velocity transitions from super- to subsonic.
It’s important to note that the M855 projectile’s ability to pierce sheet metal declines significantly by ~333 yards. Also, it is no longer effective for engaging a specific target at ~550 yards and beyond.
*For reference, a 1:8”, 1:9” or 1:10” rate of twist is considered adequate to stabilize a 62 grain 5.56 projectile. For a 55 grain projectile, the ideal rate of twist is 1:10” or 1:12”.
Is M855 Ammunition Armor Piercing?
Granted, a helmet is technically a piece of armor, although the M855 cartridge is still not classified as “armor piercing.” According to the ATF, an armor piercing cartridge (A) can be fired in a handgun, and (B) has a bullet which is constructed entirely from “one or a combination of tungsten alloys, steel, iron, brass, bronze, beryllium copper, or depleted uranium.”
The 5.56 is not a handgun cartridge. Furthermore, its core does contain steel, but it is not entirely made of steel – and lead isn’t included on the ATF’s list of “no-no metals.” We must point out that we are not lawyers or qualified to give legal advice. Even so, it is our understanding that M855 ammunition does not qualify as armor piercing.
Is M855 Ammunition Magnetic?
M855 ammo is not literally magnetic; it does not exhibit magnetism. But because its bullet contains steel, it will attract a magnet – and that is important to touch on.
Many commercial gun ranges do not permit “magnetic” ammo on their premises. That is because a bullet which contains steel has a higher likelihood of (A) scattering sparks when it hits a hard surface, (B) deflecting shrapnel back at the firing line after striking a hard surface, and (C) damaging range equipment.
The lesson to take away is this: many ranges have banned M855 ammo. If your go-to range is one of them, then you probably don’t want to order a case of ammo you’ll be unable to fire there.
The Takeaway
The 5.56×45 M855 cartridge is loaded with a 62 grain “penetrator” projectile, which has (A) a copper alloy shell with a green-painted tip, and (B) a core which is comprised of a lead alloy rear section and a solid steel front section. The M855 projectile is designed to pierce ~1/8” thick sheet metal at ranges up to ~656 yards. The M855 projectile may break in half upon entering soft tissue. Its relatively heavier weight gives the M855 projectile greater resistance to wind drift, as well as a farther effective range. M855 spec ammo is not armor piercing by definition, but many commercial ranges do prohibit it for safety reasons.
And there you go! You are now an expert on M855 ammo. Next time you go to a party and see two people politely conversing, walk up to them and say “Hey! Let me tell you about 5.56×45 M855 ammunition!” You will become the life of that party, as well as make many new friends.
