First Run Premium Bolt Carrier Group

This limited run of 200 pieces was our first production of a mil-spec bolt carrier group for the AR-15/M16/M4 platform. These were offered at an introductory price from MSRP:

Umbrella Corporation AR-15 Bolt Carrier Groups are our take on a premium, no snake oil, combat ready BCG. Each and every bolt is proof fired, ultrasonically cleaned, tested via magnetic particle inspection (MPI), and once certified, parkerized for corrosion protection and lube retention. In keeping with a superior product, we don't utilize a Crane O-Ring as a crutch to increase extractor tension. Instead, our bolts are built with a mil-spec black insert coupled with a 5-coil high load extractor spring that's compatible with all DI gas system lengths. It's rated for 150K+ cycles to outlast your rifle barrel many times over. And of course we manufacture these to the finest standards and give an unconditional guarantee against material defect and manufacturing failure. Assembly/function check by a qualified Armorer is required.

Specifications

• Bolt precision machined from Carpenter Technology No. 158 alloy, carburized/case hardened, shot peened per ASTM B851/SAE AMS2430, vibratory tumbled, individual high pressure/proof test fired, individual magnetic particle inspection, ultrasonically cleaned, markings deep laser engraved (SP=Shot Peened/HPT=High Pressure Tested, MPI=Magnetic Particle Inspection/158UC=Car Tech 158 alloy type & Umbrella Corporation), manganese phosphate
• Extractor, machined 4140 Tool steel alloy, hardened, shot peened per ASTM B851/SAE AMS2430, markings deep laser engraved (SP=Shot Peened/4140UC=alloy type & Umbrella Corporation), manganese phosphate, precision machined and ground S2 shock resistant tool steel alloy retaining pin
• Extractor Spring, 5 coil, ASTM Grade A401 Chrome Silicon wire stock, heat treated, stress relieved, Molybdenum-Disulfide infused, cryogenic processed (all post winding), mil-spec insert (premium spring eliminates need for Crane O-Ring)
• Ejector, S2 shock resistant tool steel alloy, hardened, shot peened per ASTM B851/SAE AMS2430, manganese phosphate
• Ejector Spring, ASTM Grade A401 Chrome Silicon wire stock, heat treated, stress relieved, Molybdenum-Disulfide infused, cryogenic processed (all post winding)
• Gas Rings, mil standard stainless steel X3
• Carrier machined from 8620 alloy, full auto profile, heat treated, hard chrome bore, precision ground gas key interface, Umbrella logo deep laser engraved, manganese phosphate
• Gas Key machined from 4130 chromoly steel alloy, heat treated, hard chrome internal, manganese phosphate, Permatex sealed, Grade 8 Torx Plus cap screws torqued and staked per mil-spec
• Cam Pin—precision machined 4340 chromoly steel alloy, heat treated/processed per mil-spec, manganese phosphate
• Firing Pin—precision machined 8640 steel alloy, heat treated/processed per mil-spec, hard chrome plate
• Firing Pin Retaining Pin—1038 carbon steel, heat treated/processed per mil-spec, manganese phosphate
• All components, material, and packaging made in the USA
• First Generation