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Kinetic Development Group SMX Muzzle Extension - 3-Inch Linear Riser Barrel Extension, 1/2x28 Threading, QPQ Nitride Heat-Treated Steel, Black - STR5-003
Product Description
Extending the barrel length of a short-profile pistol-caliber carbine (PCC) or sub-gun configuration traditionally forced shooters to adopt heavy, clumsy barrel shrouds. Trying to get muzzle threads past a recessed handguard shroud on your workbench using thin spacers or stacked shims can result in loose accessory fitment and accuracy-robbing baffle strikes. The **Kinetic Development Group® SMX 3" Muzzle Extension (STR5-003)** completely flatlines this barrel recess constraint, delivering a rigid, single-piece barrel extension block designed to move your muzzle attachments out past handguard limits.
Proudly engineered and CNC-machined from a solid core of **high-tensile structural carbon steel alloy**, this 3-inch linear extension is optimized specifically to match the muzzle contours of standard intermediate firearms. The structural cylinder is treated with an ultra-hard, corrosion-resistant **QPQ black nitride finish** to fight off aggressive carbon fouling and high heat levels. Cut with clean **1/2x28 TPI threads**, this barrel extension gives you a rock-solid, concentric mounting platform for attaching suppressors, muzzle brakes, or flash hiders well clear of your forward support hand.
Finished with integrated wrench flats at the rear hub base to prevent slipping during installation, this turn-key armorer modification ensures absolute accessory tracking right on your workbench.
*Armorer Bench Notes & Real-World Muzzle Staging Guidance: The Kinetic Development Group STR5-003 package arrives fully complete with the pre-machined 3-inch steel muzzle extension cylinder. PROPRIETARY INTERMEDIATE COMPONENT INTERFACE MATRIX: This linear adapter is engineered natively, strictly, and cross-compatibly to mount onto **firearm barrels featuring 1/2x28 TPI muzzle threads**. *Host Firearm System Focus:* It is customized perfectly to thread onto the **Grand Power Stribog SP9 series (SP9A1/SP9A3)** and standard 9mm AR-15 / PCC platforms to clear recessed handguard lips on your bench. Muzzle Thread Exit Standard: The front exit hub replicates the identical **1/2x28 TPI right-hand external pitch** to receive standard 9mm or 5.56mm muzzle components. Bore Clearance Safety Warning: Always visually verify that the internal bore diameter provides clean physical passage for your projectile (such as 9mm or 5.56mm) before firing. Never force larger .40 S&W or .45 ACP rounds through this tight structural tube downrange. Armorer Workbench Custom Staging Sequence: 1. Visually and physically confirm your host firearm platform is completely clear of live ammunition, the magazine is removed, and the chamber is safe. 2. Clean your factory barrel threads thoroughly with a wire brush to remove carbon dust and storage grease. 3. Thread the SMX extension directly onto the muzzle shoulder by hand clockwise until it bottoms out flush. 4. Fit a proper wrench onto the machined rear flats and torque the extension firmly down to exactly **20 to 25 foot-pounds (ft-lbs)**. 5. Thread your preferred muzzle brake or suppressor onto the new front threads, using a fresh crush washer or shim kit to line it up perfectly on your bench before heading out to the range.*
Key Features
- 3-Inch Linear Barrel Riser: Adds 3 inches of clean linear clearance to push suppressors and blast deflectors safely past tight handguard shrouds.
- Premium QPQ Nitride Armor: Liquid-ferritic nitrocarburized coating creates an incredibly hard, scratch-resistant surface that protects against hot carbon gases.
- High-Tensile Steel Core: Precision CNC-machined from tough structural carbon steel bar stock to prevent flex distortion or thread binding under hard heat cycles.
- Concentric 1/2x28 Tracking: Built with high-precision internal and external thread tracking to guarantee accurate alignment and prevent bullet strike variables.
- Integrated Wrench Flats: Machined with low-profile wrench indexing slots at the base hub to give you a secure grip and prevent tool slipping during torque down.
- Sleek Low-Profile Silhouette: Features a uniform, slim outer diameter profile that blends cleanly with standard factory barrel lines for a smooth look on the bench.
Product Specifications
- Brand: Kinetic Development Group LLC® (KDG / Fort Washington, Maryland)
- Model Line: High-Performance Technical Muzzle Systems & Barrel Specialty Components
- MPN/SKU Code: STR5-003 (3-Inch Muzzle Extension Base SKU)
- UPC Code Profile: 850045704087
- Muzzle Thread Pitch Spec: 1/2x28 TPI (Standard Right-Hand Micro Threads Per Inch Pitch)
- Front Output Thread Standard: 1/2x28 TPI Right-Hand External Thread Extension Channel
- Firearm Platform Compatibility: Grand Power Stribog SP9 Series, 9mm AR-15, and Variant 1/2-28 PCC Muzzles
- Extension Body Core Material: Premium CNC-Machined Heavy-Gauge High-Tensile Carbon Steel Alloy Billet
- Exterior Surface Dressing: Performance Hardened QPQ Black Nitride Non-Reflective Matte Coating
- Installation Tool Interface: Parallel Machined Dual-Slot Rear Hub Wrench Flats Array
- Fastener Mounting Torque Spec: 20 to 25 Foot-Pounds Maximum Recommended Torque Baseline
- Full Kit Component Checklist: Completed SMX 3" Muzzle Extension Adapter Sleeve Core
- Packaging Format Class: Factory Poly Bag Presentation Pack with KDG Branded Header Cards and Track Labels
- Product Type Category: Rifle Components / Muzzle Devices & Barrel Thread Riser Extensions
- Overall Module Linear Length: 3.00 Inches (~76.2 mm Linear Total Component Tracking Dimension)
- Net Component Module Mass: ~2.80 Ounces (~79.3 Grams Balanced Front-End Structural Mass Profile)
- Country of Quality Manufacture: Developed, Sourced, Machined, and Performance-Tested Proudly in the USA
- Warranty Tracking Protection: Fully Backed by Kinetic Development Group Factory Materials Defect Cover
