Brownells194199638
Brownells M16 Bolt Carrier Group, Mpi Inspected, Chrome$130.33
Availability: In Stock
Current Stock: Out of stock
The Brownells BRN-4 Bolt Carrier Group in phosphate chrome is a complete, ready-to-install upgrade for anyone running an AR platform rifle who wants proven reliability and durability without the headaches of sourcing individual parts. This isn't a stripped carrier—it comes fully assembled with bolt, extractor, ejector, firing pin, springs, and retaining hardware, so you can drop it straight into your upper receiver and get back to shooting.
Brownells engineered this carrier for serious use. The manganese phosphate-finished 8620 steel carrier is hardened to handle sustained high-round-count sessions, and the enlarged tail design prevents tilting from piston impact—a detail that matters when you're pushing your rifle hard. The 9310 steel bolt gets a chrome finish for fast cleanup after a range day, and that chrome-finished 4340 steel firing pin follows the same logic: corrosion resistance and ease of maintenance. The extractor stands out: it's finished in manganese phosphate rather than chrome because that grittier texture grips brass more reliably, ensuring consistent extraction across thousands of rounds. The S7 tool steel ejector rounds out the package with a phosphate finish matching the carrier.
Compatibility is straightforward. This is a full-length M16-type carrier with the MR556 cutout, making it at home in MR556 and 416 upper receivers, and it's a drop-in upgrade for any standard BRN-4 build. If you're rebuilding after wear, replacing a carrier that's seen better days, or just want a complete BCG from a manufacturer known for attention to detail, the BRN-4 in phosphate chrome delivers functional, unpretentious performance.
| Carrier Material | 8620 steel, manganese phosphate finish |
| Bolt Material | 9310 steel, chrome finish |
| Extractor Material | 4340 steel, manganese phosphate finish |
| Ejector Material | S7 tool steel, manganese phosphate finish |
| Firing Pin Material | 8740 steel, chrome finish |
| Carrier Type | Full-length M16 with MR556 cutout |
| Included Components | Carrier, bolt, extractor, ejector, firing pin, extractor spring, firing pin spring, extractor o-ring, firing pin retaining pin |
The BRN-4 is a full-length M16-type carrier with an MR556 cutout, making it compatible with MR556 and 416 upper receivers. It's also a direct replacement for any existing BRN-4 carrier. If you're running a different platform or upper, confirm your upper's specs before purchasing.
You get the complete assembly: the carrier, 9310 steel bolt, extractor, ejector, and firing pin, plus the extractor spring, firing pin spring, extractor o-ring, and firing pin retaining pin. It's a full BCG—nothing else needed for installation.
The phosphate finish on the extractor provides a grittier surface that grips brass more securely, ensuring reliable and consistent extraction. The chrome bolt and firing pin, by contrast, prioritize corrosion resistance and ease of cleaning in high-use scenarios.
The manganese phosphate-hardened 8620 steel carrier is engineered to handle sustained high-round-count firing schedules, including full-auto fire. The enlarged carrier tail also prevents tilting from piston impact, a design feature that supports demanding use.
SKU: 194200220 • Weight: 0.82oz
Availability: In Stock
Current Stock: Out of stock
The Brownells BRN-4 Bolt Carrier Group in phosphate chrome is a complete, ready-to-install upgrade for anyone running an AR platform rifle who wants proven reliability and durability without the headaches of sourcing individual parts. This isn't a stripped carrier—it comes fully assembled with bolt, extractor, ejector, firing pin, springs, and retaining hardware, so you can drop it straight into your upper receiver and get back to shooting.
Brownells engineered this carrier for serious use. The manganese phosphate-finished 8620 steel carrier is hardened to handle sustained high-round-count sessions, and the enlarged tail design prevents tilting from piston impact—a detail that matters when you're pushing your rifle hard. The 9310 steel bolt gets a chrome finish for fast cleanup after a range day, and that chrome-finished 4340 steel firing pin follows the same logic: corrosion resistance and ease of maintenance. The extractor stands out: it's finished in manganese phosphate rather than chrome because that grittier texture grips brass more reliably, ensuring consistent extraction across thousands of rounds. The S7 tool steel ejector rounds out the package with a phosphate finish matching the carrier.
Compatibility is straightforward. This is a full-length M16-type carrier with the MR556 cutout, making it at home in MR556 and 416 upper receivers, and it's a drop-in upgrade for any standard BRN-4 build. If you're rebuilding after wear, replacing a carrier that's seen better days, or just want a complete BCG from a manufacturer known for attention to detail, the BRN-4 in phosphate chrome delivers functional, unpretentious performance.
| Carrier Material | 8620 steel, manganese phosphate finish |
| Bolt Material | 9310 steel, chrome finish |
| Extractor Material | 4340 steel, manganese phosphate finish |
| Ejector Material | S7 tool steel, manganese phosphate finish |
| Firing Pin Material | 8740 steel, chrome finish |
| Carrier Type | Full-length M16 with MR556 cutout |
| Included Components | Carrier, bolt, extractor, ejector, firing pin, extractor spring, firing pin spring, extractor o-ring, firing pin retaining pin |
The BRN-4 is a full-length M16-type carrier with an MR556 cutout, making it compatible with MR556 and 416 upper receivers. It's also a direct replacement for any existing BRN-4 carrier. If you're running a different platform or upper, confirm your upper's specs before purchasing.
You get the complete assembly: the carrier, 9310 steel bolt, extractor, ejector, and firing pin, plus the extractor spring, firing pin spring, extractor o-ring, and firing pin retaining pin. It's a full BCG—nothing else needed for installation.
The phosphate finish on the extractor provides a grittier surface that grips brass more securely, ensuring reliable and consistent extraction. The chrome bolt and firing pin, by contrast, prioritize corrosion resistance and ease of cleaning in high-use scenarios.
The manganese phosphate-hardened 8620 steel carrier is engineered to handle sustained high-round-count firing schedules, including full-auto fire. The enlarged carrier tail also prevents tilting from piston impact, a design feature that supports demanding use.
SKU: 194200220 • Weight: 0.82oz