The bolt carrier is an indispensable component of semi-automatic firearms like AR-15s and MSRs. The assembly contains the bolt, bolt carrier, and a firing pin–each of which must operate in excellent condition.

When the gun’s hammer strikes the firing pin, the pin is pushed forward and strikes the cartridge’s primer cap. The priming mixture inside the cartridge explodes, propelling the bullet out of the barrel.

The priming mixture is typically a smokeless powder, and while it’s effective at firing bullets, no primer powder burns with perfect efficiency. This means a little bit of carbon is deposited onto the inner walls of the barrel while shooting.

After multiple uses, the carbon buildup gets thicker and can become almost solid, causing the rifle’s parts to stick together, creating an unsafe and virtually inoperable firearm.

Otis Technology’s B.O.N.E. Tool is a compact device that can scrape away carbon buildup on the firing pin, bolt, and bolt carrier in minutes.

The B.O.N.E. Tool breaks down carbon buildup in four simple steps:

Step 1: Disassemble the bolt carrier assembly.

Step 2: Insert the bolt carrier scraper end of the tool into the bolt carrier. Twist to remove carbon buildup and other fouling.

Step 3: Insert the bolt into the bolt scraper end of the tool. Twist to remove carbon buildup and other fouling.

Step 4: Insert the firing pin into the firing pin scraper. Twist to remove carbon buildup and other fouling.

It’s as easy as that.

The B.O.N.E. Tool comes in 5.56mm and 7.62mm sizes, suiting most AR- and MSR-style firearms. It also comes with an 8-32 threaded hole so you can twist it with a T-handle grip if desired.