Brownells 75th Anniversary - A Shooting Heritage

BRN-4 Complete Bolt Carrier Group for 416 Type Firearms

This Completely assembled BRN-4 Bolt Carrier Group is ready to drop into HK® 416, MR556 or other compatible upper receivers & firearms.  Utilizing high quality materials, finishes and inspection criteria, this BCG provides great value as a replacement or build component.  

The Brownells BRN-4 bolt is machined from high performance 9310 steel, heat treated, magnetic particle inspected for defects and finished in Black Nitride. The Black Nitride finish combined with the piston operating system makes for extremely simple cleanup.

BRN-4 Bolt Carrier Group is designed to be compatible with standard AR-15 or M16 type triggers.  Common AR-15 aftermarket drop-in, cassette or mil-spec type triggers will work with the BRN-4 BCG.

The nitride finished, 8620 forged tool steel carrier operates smoothly in the upper, thanks to the high lubricity of the nitride finish.  The integrated piston key removes any concern of staked gas keys working loose and makes for an extremely strong carrier.  Also, by forging the carrier instead of machining from bar stock, the carrier has an extremely strong internal material structure.  

Includes Bolt with Extractor & Ejector assembly, Carrier (M16 type), Cam Pin, Firing Pin, Firing Pin Spring, Firing Pin Retainer.
Carrier is compatible with 416 Type Firearms as well as MR556 Firearms (both military/LE & commercially available Heckler & Koch® Firearms).


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Cartridge: 5.56 mm NATO

Finish: Black Nitride