Bolt Carrier Group & Silver Alpha Knife Combo

As with previous generations, Umbrella Corporation AR-15 Bolt Carrier Groups are our take on a premium, no snake oil, combat ready BCG. Each 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 many of our competitors. This third gen product is manufactured to the same high standards with an unconditional guarantee against material defects and manufacturing failure. We used to challenge customers to compare our Bolt Carrier Group specs against the competition, because back then, no manufacturer offered the extensive details that we did, likely because most had no idea what the specs actually were without access to the technical data package. It shouldn’t have been a surprise to find our product specifications lifted word for word right from our website by well-known competitors, but that’s exactly what happened. Flattering? Sure, but obviously bad for consumers who were being tricked and misled by companies they trusted. These days, AR providers post material specs sourced from the internet and each other, still without having access to the M4 TDP. Or maybe they get the details from the contract BCG manufacturers they buy from, though nondisclosures typically prevent that. Regardless, as we’ve always done, we post our very detailed specs, so you know exactly what you’re getting. And don't fall for the 9310 alloy bolt substitute; it’s 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. We’ve updated our USA made TorxPlus carrier key screws with the splines and knurling of Ned Christiansen’s (Michiguns) excellent OCKS (Optimized Carrier Key Screws) process. Assembly/function check by a qualified Armorer is recommended.

Specifications

• 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 per Mil-Std-171, finish 5.3.1.2
• 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 per Mil-Std-171, finish 5.3.1.2
• 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 per Mil-Std-171, finish 5.3.1.2
• 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, 18Cr-9Ni mil-spec stainless alloy per AMS5906B, X3
• Carrier machined from AISI 8620 aircraft quality 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 per Mil-Std-171, finish 5.3.1.2
• Carrier Key machined from 4130 chromoly steel alloy per ASTM A108/A322-13, heat treated, hard chrome internal, manganese phosphate per Mil-Std-171, finish 5.3.1.2, Permatex sealed, Grade 8 Torx Plus cap screws, OCKS knurled/splined, torqued and staked per mil-spec
• Cam Pin—precision machined 4340 chromoly steel alloy per SAE AMS6415T/AMS6484D, heat treated/processed per mil-spec, manganese phosphate per Mil-Std-171, finish 5.3.1.3, 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 per Mil-Std-171, finish 1.2.2.4
• Firing Pin Retaining Pin—1038 carbon steel, heat treated/processed per mil-spec, manganese phosphate per Mil-Std-171, finish 5.3.1.2
• All components, material, and packaging made in the USA

For many years we’ve wanted to offer an Umbrella blade, but we never found the right fit with any existing knife designs or manufacturers on the market. So, in 2020, we decided to take the plunge ourselves and started working on several prototypes with the plan to make our first knife a larger, fixed blade “fighting” design. After multiple revisions and working prototypes, we settled on the model you see here—a fast but heavy-duty bowie with a long clip point, crafted from Crucible’s excellent CPM 3V tool steel, proudly melted, and manufactured in the USA.

CPM 3V is a particle metallurgical alloy. This process imparts unique features upon a material creating an extremely fine grain structure, the absence of macro-segregation, improved forgeability and machinability, with improved properties and obvious performance benefits. The powder process results in a homogenous and refined microstructure that greatly enhances the material’s strength and toughness compared to conventional ingot product. CPM 3V is a high toughness, wear-resistant tool steel designed to provide maximum resistance to breakage and chipping. However, it is not stainless steel and will rust if not properly maintained.

This first knife design, model Alpha, is machined to a final .275” thickness with a distal taper from the ricasso to the point, and likewise along the full tang. This makes for a strong, but lively knife in the hand. The blade length from the guard face is 8" to the tip, with approximately 5 1/4" from the guard back to the pommel. The handle is slightly over three quarters of an inch in thickness. Hardness is HRC ~60-62. We are offering two versions; a subdued, black PVD coated blade for increased corrosion protection, and a traditional model in the white, no coating, but with a very clean looking belt satin grind blade finish. Handle scales are oil impregnated black canvas micarta with custom Torx screws keeping the scales attached. The knife comes with a Kydex sheath and Blade-Tech’s excellent Tek-Lok attachment clip.

For this first batch, we are producing 100 of each variation. Blades are serial numbered and packaged in a custom Umbrella Corporation presentation box. Knives are warrantied against manufacturing defects. Abuse (knives are not prybars), along with damage from use, and typical wear and tear is expected and not covered.