With strength in mind, Toolcraft made their Bolts from heavy duty 9310 Alloy Steel and their Bolt Carriers from 8620 case-hardening aircraft grade steel. 9310 steel has a high core strength rating, high fatigue strength, and a high harden-ability rating overall. Normally, 9310 steel is used for gears and crankshafts in massive trucks and large aircraft, so its easy to see why it would make an ideal Bolt for an AR. Why 9310 instead of Mil-Spec Carpenter 158 steel? Simple, 9310 is an AISI standard grade of tool steel which, when properly treated, actually makes it about 7% stronger than “mil-spec” Carpenter 158. The carrier material, 8620 is used for various aircraft and vehicular applications, has a superior toughness rating, and features solid overall strength properties. When you combine these two steels with Toolcraft’s superb machining, you get a BCG that is an ideal choice for your next 5.56x45mm/.223 Rem (.300 Blackout) AR build.
The Toolcraft 5.56×45 NATO/.223 Rem (or .300 Blackout) Bolt Carrier Group comes in the Nickel Boron finish to reduce overall wear and friction, and for upgrading your existing AR build. These Full Auto M16 Profile Direct Impingement BCG designs have multiple features that separate them from the average AR Bolt Carrier Group. They are Magnetic Particle Inspected for Quality Control, and built to Mil-Spec standards throughout. They have Mil-Spec 8740 Steel hard chromed Firing Pins, Mil-Spec Gas Keys with Grade-8 screws that are staked and sealed with Permatex No.3, and they have shot-peened case-hardened D2 tool steel extractors. These Toolcraft Inc. BCGs come from the factory with a Lifetime Replacement Warranty on the entire BCG. Plus, with the AR15Discounts satisfaction guarantee, you can buy your AR build components without apprehension. Our guarantee says if you are unhappy for any reason, you can send it back to us within 30 days for a full refund. No worries. At the time this was written, these excellent BCGs had hundreds of 5-STAR ratings from around the web making them an exquisite choice for your next 5.56 NATO/.223 Rem, .300 Blackout AR build. Get yours today!
NOTE- The Nickel Boron coating is well known for reducing friction because of its molecular structure, it offers great heat dissipation properties, reduces wear on the BCG and the corresponding parts, and it increases the longevity of the BCG. Nickel Boron coatings are also known to reduce problems with function due to the decrease in overall friction and wear.
• Gas system: Direct Impingement
• Caliber: 5.56x45mm NATO/.223 Rem, .300 Blackout
• Finish: Nickel Boron Coating
• Bolt: 9310 Alloy Steel (High Hardness)
• Carrier: 8620 Aircraft Grade Steel
• Extractor: Shot Peened and Case Hardened D2 Tool Steel
• Firing Pin: Mil-spec 8740 steel with hard chrome finish
• Gas Key: Mil-Spec w/ properly staked Grade-8 screws and sealed with Permatex No. 3
• Cam Pin: 8620 Steel w/ Black Nitride Finish
• Quality Control: MPI Inspected for QC