CMMG Firing Pin Features The CMMG Firing Pin is machined from stainless steel for consistent strike energy and long term resistance to wear corrosion and carbon buildup inside the bolt carrier group. Built specifically for the MK4 platform it is sized and shaped to drop directly into a compatible AR-15 bolt without additional fitting or gunsmithing. Its silver stainless finish matches factory appearance while standing up to repeated firing cycles across .223 Rem 5.56 and .300 AAC Blackout chamberings. A properly functioning firing pin is critical to reliable ignition and this component is built to CMMG s exacting specifications. Replacing a worn or damaged firing pin is one of the simplest ways to restore a rifle s reliability without a full bolt carrier group replacement. This part installs using the same takedown process as the factory original keeping maintenance quick and accessible for home gunsmiths. CMMG s reputation for durable AR-15 components carries through to this firing pin making it a trusted choice for MK4 owners. Shooters looking to keep their rifle running dependably will find this a practical cost effective replacement part. CMMG Firing Pin Specifications Manufacturer: CMMG Model: Firing Pin Type: Parts Kit Compatible Hosts: AR-15 MK4 Caliber: .223 / 5.56 / .300 AAC Blackout Color: Silver Material: Stainless Steel Available At: GrabAGun