Home Editorials Green Tip 5.56 NATO (M855): What Is it? What Is It Good For? By: Megan Kriss

Green Tip 5.56 NATO (M855): What Is it? What Is It Good For? By: Megan Kriss

Green Tip 5.56 NATO (M855): What Is it? What Is It Good For?   By: Megan Kriss

“Green tip” 5.56x45mm NATO rounds, properly called M855 rounds, have been a subject of much debate and controversy in recent years. To help clear the air (as much as we ever can around an issue like this, anyway), we wanted to take this time to talk about all things green tip.

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We’ll cover what exactly it is, why it’s such a spicy topic, what you can actually shoot it out of, and more. Let’s dive right in.


Originally called SS109, when it was introduced in the 70s, what we currently know as M855 or Green Tip 5.56 ammo was originally developed by the Belgians, and then passed NATO certification trials and was adopted formally. 

It was then picked up by the US to replace generally low-quality M193 5.56 ammo in the early 80s, rechristened the M855, and was off to the races. 

Incidentally, the green tip that has become somewhat iconic (and apparently scary) in the years since came about as a result of the US military wanting a way to differentiate the newer M855 from the older, crappier, M193, which was mostly relegated to training use and National Guard units.

Ammo manufacturers quickly started making M855 for the civilian market, and like most gun-related bits and bobs the military uses, it quickly caught on and started selling like hotcakes…well, if people actually bought hotcakes.

Knight’s firearm collection is unparalleled. Here’s an Armalite AR-15, serial number 000001, rescued from a storage closet at Fairchild Corporation. It was a prototype of the 5.56mm rifle that would become the U.S. Army M-16.

A few companies started putting an “X” in front of the name, changing it to XM855, basically just to denote that it was being sold to civilians. It’s not actually any different, so don’t panic if you see it on a shelf or in a product listing somewhere.

In the years since, even though M193 isn’t used by the military anymore, M855 has kept the green tip in order to differentiate it from other rounds like M995 “black tip” ammo, which is actually armor piercing. 

Oh yeah, we should mention: Green tip ammo isn’t armor-piercing, by almost any definition. 

I mean, yeah, if you go back in time to the Battle of Hastings, Agincourt, or any other medieval conflict featuring knights in plate armor…you could do some damage. Today though, M855 has a much harder time against modern body armor, car doors, and even windshields at close range. 

That’s because most (80%) of the round is in fact just lead like any other, so you don’t really get the armor-piercing effect of a steel penetrator or tungsten core that could actually defeat kevlar or steel plates. Basically, M855 sucks against armor, which is why we have M995.*

*If you’ve ever played Escape From Tarkov, you probably already knew that.

The round does have a semi-steel core, but it’s such a small percentage of the round that it doesn’t really change armor penetration characteristics an appreciable amount.

Today, M855 has been the subject of debate in Congress and online because some folks have attempted to label it an armor-piercing round. The ATF was then caught by their own regulations of what defines an armor-piercing round, and the fact that M855 doesn’t meet said definition.

Will that change? Who knows. It doesn’t seem to be a big priority right now, and M855 is easily purchasable through a variety of retailers. ATF regulations, as we all know, are always subject to change and reinterpretation. 


Shooting. That’s about it. Technically, M855 is better at penetrating barriers like thin walls and car doors than normal 55gr lead 5.56 is, but this really isn’t an attractive characteristic for most normal shooters.

This is bad for home defense since you run a much higher risk of overpenetration through walls. Even if you’re not worried about overpenetration, M855 isn’t advantageous on soft targets, either. Because of the steel penetrator, M855 acts more like an ice pick when it hits soft tissue and just pokes a hole straight through. In other words, it’s not a great pick for stopping bad guys.

One small problem with M855 is that not all shooting ranges allow you to use it. The steel tip isn’t really “armor piercing,” but it is damaging to steel targets and is a higher fire risk than standard ammo. Because of this, a LOT of public and private ranges ban the use of this ammo since they don’t want their targets damaged or the land burnt down.

No M855!

So if it’s bad for home defense and hard to plink or train with… why get it?

Generally speaking, because it’s cheap. Or at least cheaper. As of the moment, I’m writing this, M855 can be had online for about 29 or 30 cents per round. The cheapest newly manufactured brass cased .223 Remington starts at 31.5 or 32 cents per round.

Since we’re still in an ammo shortage, the prices aren’t great. Before COVID, I remember seeing M855 for five or more cents less than other comparable options. 

Between the price and the fact that it’s good ammo, this is a great option for stocking really deep.


If you want to shoot Green Tip 5.56x45mm NATO, otherwise known as M855 or XM855, you have a couple of options. 

First, if you have any 5.56x45mm gun, you can run this ammo. That means most of your off-the-shelf AR-15s, Ruger Mini-14, Steyr Aug, any of the 2.6 billion 5.56 AR-15-style rifles out there, etc. If it’ll handle any 5.56x45mm ammo, it can shoot green tip ammo.

This makes M855 a great option for anyone looking for cheap, but still proven and effective ammo to shoot, or to stock up on in case of another run on ammo/end-of-the-world scenario. 

We seem to be experiencing “once in a lifetime” events about once a week now, so hey. Maybe the preppers really have been right all along. “Buy it cheap and stack it deep” is definitely an option with M855, especially given that you can run it in any 5.56x45mm gun or upper receiver. 

MPVO (2)
Not an AR-15, still 5.56 NATO

Unfortunately, because 5.56 chambers are shaped a bit differently than .223 Remington chambers, 5.56 ammo in a .223 can create dangerously high pressures that can blow out brass, push out primers, and potentially damage your gun (or you). 

That means green tip ammo just isn’t safe to shoot out of a .223 Remington chamber, so if your barrel says .223 Rem instead of 5.56x45mm NATO on the side, you can’t use it safely.

That said, you can also shoot green tip ammo out of a .223 Wylde chamber if you have one of those lying around. 

The .223 Wylde chamber combines some of the geometry of the 5.56 chamber with some of the throat dimensions of the .223 Remington chamber to create a chamber that can handle higher pressures while keeping the accuracy advantages of the .223 Remington chamber.


Hopefully, that clears the air around the M855 round! This simple little loading has been the subject of much-heated discussion, which always brings with it a host of misinformation, even from well-intentioned folks. 

Now you should know all the important bits, and feel better about running this ammo in your guns. 

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