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TacFire 16" Unassembled .300 Blackout AR-15 Rifle Build Kit with Lower Parts Kit - RK300-LPK
Product Description
Diving into a custom firearm assembly or sourcing parts for a dedicated intermediate-range tactical build frequently introduces an immediate logistical and structural bottleneck: component compatibility and tolerance stacking. Sourcing separate barrels, gas blocks, upper receivers, bolt carriers, and lower small parts from scattered manufacturers often leaves builders dealing with out-of-spec dimensions, sluggish cycles, or failure-to-feed geometry slips. The **TacFire® 16" Unassembled .300 Blackout Rifle Build Kit with Lower Parts Kit (RK300-LPK)** completely eliminates these multi-vendor headaches, packaging a comprehensive, factory-matched suite of internal and external components directly into a single unyielding workbench bundle.
Precision-engineered as a complete, builder-ready assembly template (minus the stripped lower receiver), this heavy-duty package brings unyielding structural stability straight to your workbench. The core of the upper foundation centers around an enhanced **stripped billet aluminum upper receiver** outfitted with precisely cut M4 feed ramps to ensure seamless, jam-free tracking for fat .300 AAC Blackout cartridges. Protecting the billet aluminum shell and its matching handguard is a uniform, non-reflective matte black hardcoat anodized jacket. This layer actively shields the underlying alloy from corrosive carbon slurry, environmental trail moisture, and abrasive friction encountered during high-intensity training strings.
In terms of downrange tracking and cyclic continuity, the core mechanical engineering of this kit is optimized for dual supersonic and subsonic performance. It features a premium **16-inch 4150 Chrome-Moly Vanadium steel barrel** treated with a slick, wear-resistant black nitride or parkerized finish. Cut with a versatile 1:7 or 1:8 twist profile, it perfectly stabilizes everything from light supersonic hunting rounds to heavy subsonic duty loads. To tame aggressive muzzle blast, the kit includes a high-efficiency multi-port muzzle brake or a specialized spiral-fluted flash can. Driven by a low-profile steel gas block paired with a pistol-length or carbine-length gas tube, this kit minimizes gas bleeding to drive an included, MPI-tested 5.56/.300BLK full-auto profile bolt carrier group with absolute structural timing.
To ensure a seamless lower frame integration loop, the RK300-LPK bundle drops a **complete AR-15 Lower Parts Kit (LPK)** directly into the box. This USA-made small parts grouping includes a conventional single-stage fire control group with case-hardened sears, a standard texturized black A2 pistol grip, and a complete 6-position or administrative buffer tube assembly. Outfitted with a 3.0-ounce standard weight buffer, heavy-duty compression spring, steel castle nut, and receiver end plate, this comprehensive bundle provides an uncompromised mechanical baseline. It lets you confidently transition a raw lower frame into a duty-ready rifle with absolute technical authority.
*Armorer Bench Notes & Technical Assembly Guidance: The TacFire RK300-LPK contains all the necessary physical elements to build out a complete, operational .300 Blackout AR-15 rifle, requiring only a standard stripped AR-15 lower receiver (FFL item) to complete the firearm build. When initiating assembly on your workbench, verify that the handguard barrel nut is torqued exactly between 35 to 60 ft-lbs using a calibrated armorer’s wrench over a secure upper receiver vise block. Apply a micro-dot of high-temperature aerosol anti-seize grease to the receiver extension threads before torquing the steel castle nut to a firm 38-42 ft-lbs, and stake the end plate into the castle nut notch to prevent shifting under intense firing vibrations. When building out the lower parts kit, utilize dedicated roll-pin punches to slide the bolt catch and trigger guard hardware into place without marring the finish. Ensure the gas block is perfectly centered over the barrel's gas port to guarantee flawless tracking and cycling timing.
Key Features
- All-In-One Builder-Ready Box: Consolidates your entire rifle build checklist—including upper, BCG, handguard, buffer assembly, and lower parts kit—under one single part code.
- Nitride-Finished 4150 CMV Barrel: Crafted from premium Chrome-Moly Vanadium steel to withstand intense thermal cycles while delivering outstanding accuracy with diverse projectile weights.
- Ultra-Slim M-LOK Free-Float Rail: Enclosed within a sleek, full-length free-float handguard featuring multi-sided M-LOK attachment windows to mount tactical lights, lasers, and vertical grips flat.
- Complete MPI-Tested BCG Included: Ships factory-equipped with a full-auto profile 5.56/.300 Blackout bolt carrier group, Magnetic Particle Inspected (MPI) to guarantee failure-free bolt integrity.
- USA-Made LPK & 6-Position Stock: Accompanied by a full domestic lower parts completion kit, a standard A2 grip, and a collapsible stock assembly to quickly fit changing physical statures or body armor.
Product Specifications
- Brand: TacFire
- Model Line: Unassembled High-Performance Rifle Completion Master Kits
- MPN/SKU: RK300-LPK (Also tracked as SS-RK300LPK)
- UPC Code Profile: 811261029859
- Caliber Focus: .300 AAC Blackout (300 BLK / 7.62x35mm)
- Barrel Length Specification: 16.0 Inches
- Barrel Material Lineage: 4150 Chrome-Moly Vanadium Steel (Nitrided/Parkerized Finish)
- Muzzle Thread Pattern: 5/8x24 TPI Standard Right-Hand Pitch
- Upper Receiver Style: Precision-Machined Stripped Billet Aluminum with M4 Feed Ramps
- Handguard System Profile: 15" Slim Free-Float M-LOK Clamping Attachment Rail
- Operating System Type: Direct Impingement with Micro Low-Profile Steel Gas Block
- Bolt Carrier Group: Included Full-Auto Profile M16 Nitrided BCG (MPI Tested)
- Charging Handle Interface: Included Standard Aluminum Charging Handle with Steel Latch
- Lower Parts Kit (LPK): Included AR-15 USA-Made Lower Completion Kit (Complete Trigger Group & Springs)
- Pistol Grip Style: Standard A2 Textured Black Polymer Handle
- Stock/Receiver Extension Assembly: 6-Position Adjustable Buttstock with Buffer Tube, 3.0 oz Buffer, & Spring
- Muzzle Device Interface: High-Efficiency Muzzle Brake or Spiral Fluted Flash Can with Crush Washer
- Net System Combined Weight: Approximately 6.32 lbs (Unassembled Component Mass)
- Country of Manufacture: United States of America
