Premium Bolt Carrier Group Gen 2

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 Tactical Springs 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. We have improved on the finish requirement of the TDP and have chosen the best materials of those allowed per spec, not the lowest cost like nearly all of our competitors. This second gen product is manufactured to the highest standards with an unconditional guarantee against material defect and manufacturing failure. We challenge you to compare our Bolt Carrier Group specs against the competition. Beyond using Carpenter's 158 alloy for the bolt, ask what alloy they use for their extractors, Extractor pins, ejectors, and whether their cam pins have a solid film lube per TDP. You will likely find they don't advertise any of these specifications.  And don't fall for the 9310 alloy bolt substitute; it is a less expensive, inferior alloy for this application. Bought into the hype and don't believe us? Ask Carpenter Tech; they manufacture both materials and will without hesitation tell you 158 is the proper, superior alloy. The draw for 9310 is that it's a decent material when heat treated properly though since there's no spec, how do you know what "proper" might be for this application? It's less costly, and you don't have to buy mill run quantities for manufacturing. It's the little things that make the real difference and we cut no corners with our Bolt Carrier Groups. Assembly/function check by a qualified Armorer is required.

Specifications

• Bolt, precision machined from Carpenter Technology No. 158 gun quality aerospace alloy, heat treated per mil-spec (stress relieve, carburize, oil quench, temper, refrigerate, repeat temper), shot peened per ASTM B851/SAE AMS2430S, vibratory tumbled, individual high pressure/proof test fired, individual magnetic particle inspection ASTM E1444/E1444M, ultrasonically cleaned, markings deep laser engraved (SP=Shot Peened/HPT=High Pressure Tested, MPI=Magnetic Particle Inspection/158U=Car Tech 158 alloy type and Umbrella manufacture), manganese phosphate
• Extractor, precision machined from 4340 tool steel alloy per SAE AMS6415T/AMS6484D (vs typical 4140; mil-spec allows for either 4140 or 4340), heat treat, shot peen per ASTM B851/SAE AMS2430S, markings deep laser engraved (SP=Shot Peened/4340U=alloy type & Umbrella manufacture), manganese phosphate
• Extractor Retaining Pin, precision machined and ground S2 shock resistant tool steel alloy per ASTM A681-08 (vs typical S7; mil-spec allows S1 to S7), heat treated per ASTM A681-08, shot peened per mil-spec print, manganese phosphate
• Extractor Spring (premium spring eliminates need for Crane O-Ring), Tactical Springs/Sprinco 5 coil, ASTM Grade A401 Chrome Silicon wire stock, heat treated, stress relieved, Molybdenum-Disulfide infused, cryogenic processed (all post winding), mil-spec black insert/synthetic elastomer extractor buffer (nitrile-butadiene, shore hardness 80+/-5 durometer per MIL-PRF-6855)
• Ejector, S2 shock resistant tool steel alloy per ASTM A681-08 (vs typical S7; mil-spec allows S1 to S7), heat treated per ASTM A681-08, shot peened per mil-spec print, manganese phosphate
• Ejector Spring, Tactical Springs/Sprinco 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 AISI 8620 aircraft qualty alloy per ASTM A108/A322-13, full auto profile, surface finish improved over mil-spec, heat treated (carburized/strain relieved per mil-spec print), hard chrome bore, precision ground gas key interface, Umbrella logo deep laser engraved, manganese phosphate
• Gas Key machined from 4130 chromoly steel alloy per ASTM A108/A322-13, heat treated, hard chrome internal, manganese phosphate, Permatex sealed, Grade 8 Torx Plus cap screws torqued and staked all per mil-spec
• Cam Pin—precision machined 4340 chromoly steel alloy per SAE AMS6415T/AMS6484D, heat treated/processed per mil-spec, manganese phosphate, solid film lubricant applied and cured per mil-spec
• 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