The firing pin is an essential part of a firearm, so it’s important to choose the right one for your AR-15 build.
And while broken firing pins are rare, a broken firing pin renders your gun completely inoperable, so having a spare on hand is a great idea.
Since they’re very affordable, with even high-end AR-15 firing pins ringing up at less than 20 bucks, and are small enough to be very easy to afford, having a spare, even if you never use it, won’t put you out when it comes to cost or storage space.
So how do you choose a firing pin? That’s what we’re here to talk about. In this guide, we’ll discuss exactly what an AR-15 firing pin is, how one works, and what to look for when selecting an AR-15 firing pin. Then we’ll talk about our top favorite firing pins.
A firing pin is an important part of the bolt carrier group (BCG) of your AR-15 (and on most other guns, for that matter, including both rifles and handguns, such as the 1911). It’s responsible for hitting the primer at the rear of the ammo cartridge, which starts the chemical reaction that causes the bullet to actually leave the gun.
We’ll talk a bit more about exactly how that works below.
An AR-15 uses what’s called a free-floating firing pin. This means that there’s no firing pin spring. You don’t need to worry about the technical details too much, just know that you don’t need to get a firing pin spring for your build and, if you’re upgrading, you’re not missing a piece when you open up your upper receiver and don’t see a pin.
How Do AR-15 Firing Pins Work?
To understand how firing pins work is basically to understand how firearms work.
When the shooter pulls the trigger, it causes a piece called a sear to release the hammer so it moves up and forward, hitting the firing pin. The firing pin then moves forward itself so that the tip of the pin hits the primer of whatever round is in the chamber.
The primer strike causes the primer to ignite, which in turn produces hot, expanding gas. That creates a high-pressure environment behind the bullet. Since the ammo’s cartridge blocks the gas from exiting to the rear of the gun, it has nowhere to go but forwards, pushing the bullet out ahead of it.
Unlike other guns, the AR-15 uses a gas system that uses gas blocks to divert some of the gas back to the bolt carrier group to automatically cycle the next round.
The video below illustrates this whole process.
What Do You Look For In The Best AR-15 Firing Pins?
There isn’t a lot of variation between AR-15 firing pins, but that doesn’t mean you should just choose one at random and hit “checkout.” There are a few things that you should keep in mind before you buy your new firing pin.
First, make sure you’re buying the right gun and I don’t just mean not buying one for 1911. In many cases, the AR-15 and M16 use interchangeable parts, but not with firing pins.
Sure, you can put an M16 pin in an AR-15 and it will perform (though it won’t make the gun capable of fully automatic fire), but the hammer will scrape the firing pin which causes the firing pin retaining pin to bend, leading you to have to frequently replace it.
You’ll also want to consider the material that your firing pin is made out of. You’ll want something that’s resistant to corrosion and wear. Fortunately, the vast majority of firing pins are made out of steel, which checks both of those boxes.
You’ll occasionally find a firing pin made out of titanium rather than steel, which also checks those boxes, plus with a lower weight. A firing pin has pretty low mass anyway, but ounces add up to pounds faster than you might expect. If you’re going for a truly lightweight build, it’s important to consider the weight of even all of your small parts to get the lightest rifle possible.
On a related note, you’ll also want a firing pin with a smooth finish. A rough finish makes it easier for carbon fouling to stick to the firing pin and harder for you to clean it during routine firearm maintenance.
A smooth finish, on the other hand, is more difficult for carbon to stick to and wipes clean much easier. It also allows for smoother movement within the firearm, preventing wear.
Best AR-15 Firing Pins Reviewed
Now let’s get to the firing pin recommendations.
1. Colt AR15 A4 Firing Pin (Our Top Pick)
If you bought a Colt AR-15, this is the firing pin that it would come with. And who better to make an AR-15 firing pin than the company that started mass producing this prolific carbine?
This stainless steel AR-15 firing pin is entirely mil-spec, which makes sense considering that Colt also produces the AR-15’s automatic equivalent, the M16, for the U.S. military.
Firing pins are already affordable, but the CMMG AR15 Firing Pin is especially so. If you already have a firing pin you like, this CMMG firing pin is a great option for keeping on hand as a spare in case yours breaks since you won’t have to sink a lot of money into a part you may not use.
And if this one breaks, CMMG offers the CMMG, Inc. Lifetime Quality Guarantee, which is just their fancy name for their limited lifetime warranty.
3. Iron City Rifle Works Titanium Firing Pin (Best High End)
Our top high-end pick is the Iron City Rifle Works Titanium Firing Pin. It has a unique titanium design which Iron City claims is 45% lighter than mil-spec, weighing just .14 ounces. At the same time, it’s harder and stronger than steel.
It’s available in six different finishes with different coating types: Raw (no coating), Blackdiamond (diamond-like-carbon coating), Copperhead (copper physical vapor deposition), C4V Gold (gold titanium nitride), Viking Blue (blue PVD), and Unicorn Tears (rainbow iridescent titanium nitride).
The smooth finishes allow for smoother, faster travel for quicker follow-up shots, as well as easy cleaning.
Lightweight but hard and strong
Available in six different coating and color options
This pin is made from steel, but the NiB-X coating is its main bragging point. The NiB-X nickel boron coating enhances lubricity, wear-resistance, and corrosion resistance. According to WMD Guns, NiB-X “delivers the highest hardness rating in the nickel boron plating industry.” Its slick surface allows for easier cleaning.
In addition, the coating process delivers a consistent coating across the entire surface, within 1 to 2 microns, so you shouldn’t have to deal with any rubbing or grinding.
NiB-X nickel boron coating
Made from steel
Smooth, consistent surface
More expensive than basic options like the Colt and CMMG firing pins
A new firing pin doesn’t make nearly as significant of a difference as new stock, handguard, or barrel, but a high-quality AR-15 firing pin is still essential for maintaining a reliable weapon. That’s true whether you’re building a new AR-15 or upgrading one you already have. If you replace the firing pin as part of a larger bolt carrier group upgrade, you’re sure to notice the difference.
And since a broken firing pin renders your gun completely useless, it’s also a good idea to keep an extra on hand so you’re not stuck with a gun-shaped paperweight until you can get a replacement.
Fortunately, firing pins are super affordable, with even high end firing pins typically ringing up at less than 20 bucks.