The AR-15 is America’s most popular rifle, and for good reason. It’s lightweight, accurate, easy to shoot, and you can run it as a rifle, carbine, or pistol, thanks to its modular design.
An AR-15 can also shoot a wide variety of 5.56mm ammunition. Some variants are set up to run 40-grain small game loads. Other mil-spec rifles prefer heavier 77-grain freedom pills that work well with suppressors.
Today, we’ll be taking a look at two of the more popular types of 5.56mm ammunition for the AR-15. 62 grain M855 vs M193 running at 55 grains.
What Is M855?
M855 is often referred to as green tip ammo for its special color coding (the projectile itself is painted green at the tip). These 5.56 cartridges push a 62-grain bullet designed with a boat tail, lead core, and a special steel "penetrator" tip. The specified muzzle velocity of M855 ammo is roughly 3,020 feet per second depending on the manufacturer. The primer and case mouth are chemically sealed, just like M193 ammunition.
Heavier and slightly slower, the M855 is a 62-grain 5.56×45 caliber bullet traveling around 3,000fps at the muzzle. The green-tipped M855 comes loaded with an 80% lead core and topped off with a 7-grain steel tip which provides the M855 with far superior penetration when compared to the M193 round.
Even though it’s slower due to the slight increase in bullet weight, the M855 actually sports a higher ballistic coefficient because of its increased length, allowing it to travel on a flatter trajectory, with less drop, and it bucks the wind better at distance.
Although many have confused the M855 round to be armor-piercing, it is not. The steel "penetrator" at the tip of the core helps it punch through barriers pretty effectively though. It penetrates glass, thin gauge metal, thick clothing, and brush rather well.
However, don’t expect M855 rounds to plow through auto glass consistently, brick, or modern body armor. Infantry units in Iraq were reportedly frustrated that their Mil-Spec M855 ammo couldn’t penetrate windshields at shorter distances.
However, there are some instances of the M855 penetrating auto windshields without any issue whatsoever.
Because M855 ammo penetrates so well, it can wreak havoc on steel targets, which is why most indoor ranges, or outdoor ranges for that matter, do not allow you to shoot green tip ammo.
When it comes to performance on soft targets, M855 leaves a lot to be desired. The same characteristics that allow it to punch through barriers, also make it more likely to pass straight through a soft target without causing any significant tissue damage. The M193 round has an edge on M855 in this instance.
That special steel "penetrator" makes the M855 projectile a little longer than the M193. This extra length requires a faster twist rate for proper in-flight stabilization.
For this reason, M855 performs well in barrels with a faster 1:7 or 1:8 twist rate.
So, if you’re shooting a rifle with a fast twist rate (1:7 or 1:8), choose M855 green tip ammo. Likewise, if you’re trying to poke holes through intermediate hard barriers, M855 green tip ammo is the way to go.
The M193 is essentially the standard, average, or ‘run of the mill’ 5.56 ammunition that most purchase. Used in massive quantities by our military; the M193 is a 55 grain, lead-cored, full metal jacket round with a muzzle velocity of roughly 3,200 fps depending on the manufacturer.
What do these characteristics mean? They mean that this lightweight bullet is flying extremely fast, and is generally unstable (tumbling) when it makes contact with a target. This tumbling effect leads to a larger wound cavity, and ultimately, better lethality.
Known to be prone to fragmentation upon contact with a target, the M193 was not made to penetrate any sort of barrier, armor, or hardened material.
Some notable advantages of M193:
Less expensive to use for training and practice
Generally easier to get ahold of than M855
Hunters prefer its terminal effects at short distances
The round can be stabilized with most barrel twist rates
Although M193 is an FMJ round, it often fragments inside soft tissue, creating a considerable wound channel. However, when it fails to fragment, M193 produces only minimal less-lethal wounds.
Many Vietnam Veterans complained about the M193. Claiming it had no significant effects on the enemies they shot at and hit. M193 also performs poorly when it comes to punching through soft barriers such as heavy clothing and thick vegetation.
If your rifle has a slower twist rate (1:9, 1:10, or even 1:12), M193 will yield better results.
M193 is more effective on soft targets that aren’t hiding behind a barrier, especially on targets 100 yards and in.
There is no clear winner in the comparison of M855 vs M193. The situation dictates the ammunition. Each round is better at different things, so it is entirely dependent on your needs and application. If penetrating barriers or engaging targets out past 100 yards is your primary concern, the M855 will likely perform better for you.
However, the M193 is probably a better choice for hunting, as it fragments more easily and causes more terminal effects in the intended target and an ethical kill.
Pricing is pretty similar
Some shooting ranges do not allow steel core bullets such as the M855
M193 prefers a 1:9 twist rate, while M855 prefers a 1:8 or 1:7 twist rate
M855 penetrates slightly better
M193 performs better against soft targets out to 100 yards