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// Small parts · Firing pin
AR15 Firing Pin, Chrome Plated
Seven dollars fifty. Which is a strange amount to be one part away from a rifle that does not fire.
$7.50
- SKU FPN-SOT-CHR
- Material 8740 steel
- Finish Chrome plated
- Spec Mil-spec print
- Fits AR-15 / M16 5.56 BCG
Questions about fit? Tell us the rifle and the barrel and we’ll confirm the right part before it ships.
// The operator’s case
Nobody buys a firing pin until they need one, and by then the rifle is already not working.
It is a slender part that takes a hammer strike thousands of times, runs through a carrier full of carbon, and gets bent, battered or lost during cleaning more often than it gets inspected. It is also one of the very few components in an AR whose failure stops the rifle completely and immediately — there is no limping on with a broken firing pin.
This one is machined to the mil-spec print from 8740 steel, precision ground, properly heat treated and chrome plated. That is the whole specification, and for this part it is the right one: 8740 is a chromium-nickel-molybdenum steel chosen for strength and toughness, and chrome plating gives the pin a hard, slick surface that carbon struggles to build on inside a dirty carrier.
At $7.50 the honest argument is not that this pin is better than the one in your rifle. It is that a spare belongs in the kit, and that when you do need one, you want it to be the correct part rather than whatever was in stock.
What this part will not do
It will not make the rifle more accurate, more reliable or faster to cycle. A firing pin either strikes the primer correctly or it does not, and a correct one does. Anyone selling you a firing pin on a performance claim is selling you something else.
It is the right part, at the right dimensions, for seven fifty. That is all it needs to be.
// Why it
Buy the spare before you need it.
01 Buy the spare before you need it
A broken or bent firing pin is a hard stop. No amount of technique gets you through it, and it is not a part your local shop reliably has on the shelf. For the price of a box of cheap range ammunition you can put a correct spare in the range bag and never think about it again — which is the entire reason this sheet exists.
02 8740 steel
A chromium-nickel-molybdenum alloy chosen for strength and durability in a part that is long, thin and struck repeatedly. Correctly heat treated, it is tough where a harder, more brittle steel would be at risk of snapping.
03 Machined to the mil-spec print
Dimensions matter here more than most places. Protrusion is what determines whether primers are struck properly — too little and you get light strikes, too much and you risk slam fires. Made to the print, this drops in and behaves as the platform expects.
04 Chrome plated
Hard, slick, corrosion resistant, and easy to wipe clean. That matters on a part that lives inside a carrier packed with fouling and gets cleaned less thoroughly than almost anything else in the rifle.
05 Precision ground
Ground after heat treatment, so the finished dimensions are held on a part that is already at final hardness rather than left to move during treatment.
06 It is what our own groups use
This is the same firing pin specification fitted in the bolt carrier groups we build. Offering it separately simply means you do not have to buy a group to get a spare.
// Specifications
The specification
| Specification | Value |
|---|---|
| Product | AR15 Firing Pin, Chrome Plated |
| SOT SKU | FPN-SOT-CHR |
| Material | 8740 steel — chosen for strength and durability |
| Specification | Machined to the mil-spec print |
| Process | Precision ground, properly heat treated |
| Finish | Chrome plated |
| Fits | AR-15 / M16 5.56 bolt carrier groups |
| Price | $7.50 |
// Before you order
Inspection and fitment.
- Check the tip, not just the shank. A firing pin is most often condemned for a chipped, mushroomed or bent tip, and that is the end you cannot see with the bolt assembled.
- Degrease before installation and keep the pin channel clean. Carbon in the channel is a more common cause of light strikes than the pin itself.
- This pin is for 5.56 AR-15 / M16 bolt carrier groups. It is not the .308 / AR-10 part, and it is not a titanium or lightweight competition pin.
- This is a component, not a firearm. If a rifle is producing light strikes or failing to fire, have it inspected by a qualified armourer rather than swapping parts at random.
WARNING: This product can expose you to chemicals including lead, which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.
Warranty. Supplied unmodified and carrying its manufacturer’s warranty in full. Second of Ten will act as the owner’s agent in any claim against that coverage where it runs broader than ours. See warranty information.
// Related
Related parts and groups
All bolt carrier group parts and the comparison → Bolt Carrier Groups →
Bombproof by Design™ and Gundaddy® are marks of Second of Ten LLC. Specifications are as published by the manufacturer and were verified on 18 AUG 2026; they are subject to change without notice. Firearm components should be installed and function checked by a qualified armourer before firing.
Bombproof by Design™
Precision // Purpose // Performance