300 Blackout is an amazing black rifle round... If you can find the right configuration. Just like 5.56/.223 love the 16" barrel, .300 BLK loves the 10.5" setup. So, naturally, we pieced together the perfect kit: This one sports a 10.5" barrel cold-forged from 4150 CMV, the best gun steel you can buy. We threw on a forged M4 upper for good measure, and topped it off with a full-auto M16 BCG and pistol gas system.
This kit ships with an 12" M-Lok handguard, a full buffer tube assembly, and an SB Tactical pistol brace. For the lower parts kit, you get an upgraded Magpul MOE grip and an enhanced, polished trigger. Finally, you get one of our 9mm 80% lower receivers! Please note this lower is designed to accept Glock style mags. Pair it with an 80% jig, and you'll be ready to build as soon as the kit shows up at your front door!
AR-9 Pistol Build Kit Specs:
Barrel Length: 10.5"
Barrel Steel: 4150 CMV, heat-treated
Barrel Finish: Nitride
Muzzle Thread: 1/2x36
Chamber: 9mm Parabellum
Twist Rate: 1:10
Muzzle Device: A2 flash hider
Receiver Material: Forged 7075 T6
Receiver Type: Flat-top w/ Picatinny
Handguard Type: Slant 12” M-Lok
Bolt Carrier Group Included: Yes
Bolt Steel: Shot-peened, MPI-tested, 8620 steel
Bolt Carrier Profile: 9mm Hybrid
Charging Handle Included: Yes
AR-9 Pistol Build Kit Features:
- Complete build kit w/ optional lower
- Includes pre-built 9mm AR upper
- Hybrid 9mm AR bolt carrier group
- High-quality CMV barrel for accuracy
- Compatible with Glock magazines
- Features enhanced, polished trigger
- Not considered a firearm, no FFL required
- Proudly built in the U.S.A.
- Backed by Lifetime Warranty
Barrel: Nitride-coated, 10.5”, chambered in 9mm Parabellum. Made of 4150 CMV steel. Heat-treated. Features 1:10 twist rate. Includes 12” slant M-Lok handguard, and A2 flash hider.
Upper: Mil-spec, made of forged 7075 T6 aluminum. Hard-coat anodized (Type III).
Bolt: Custom 9mm AR hybrid bolt carrier group. Compatible with any 9mm Glock magazines. Heat-treated. Nitride finish. 8620 steel.
80% Lower: Complete with optional AR-9 80% lower. Mil-spec fittings. Type III Hardcoat anodized finish.
Lower Parts Kit: Mil-spec 9mm AR lower parts kit. Enhanced, polished trigger (EPT). Six-position buffer tube. SB Tactical Pistol Brace. Carbine buffer spring. 9mm pistol buffer.
Charging handle: Standard AR-15 charging handle.
Please note: If completing your AR-9 build using the optional 80% lower, please select an AR-15-compatible 80% jig from our available options.
Shipping of various parts and/or accessories are prohibited to states and locales (ie New Jersey, California, New York, etc…) with restrictions against certain parts and/or accessories or “assault weapons” (i.e. states with high-capacity magazine restrictions, manufacturing of semi-automatic weapons, etc..). It is your responsibility to be aware of your local firearms laws before purchasing from our website or machining a firearm. We try our best to keep our shipping page current, but laws change daily
80-Lower.com only ships within the United States. Federal legislation dictates we cannot ship our products internationally.