Ruger AR STOCK KIT M4 STOCK - 91007 - 736676910076
Product Description
Building or converting an AR-15 lower receiver can present frustrating sourcing hurdles when buffer system components are sold separately. Mismatched receiver extensions, incorrect carbine buffer weights, or out-of-spec action springs often lead to short-stroking, failure-to-feed malfunctions, or loose stock wobble. The Ruger AR Factory M4 Stock Kit (91007) solves these assembly and compatibility issues by providing a complete, factory-matched Mil-Spec stock hardware system in one comprehensive package.
Engineered to Sturm, Ruger & Co.’s original equipment manufacturer (OEM) standards, this complete kit features a 6-position collapsible M4-style buttstock molded from high-impact polymer. The assembly includes a Mil-Spec diameter 7075-T6 aluminum receiver extension (buffer tube), a standard carbine action spring, a 3.0 oz carbine buffer, a castle nut, and a lower receiver end plate. The 6-position adjustment channels allow shooters to quickly tailor length-of-pull (LOP) for body armor, thick winter clothing, or compact vehicle staging.
Ideal for custom AR-15 rifle builds, converting fixed-stock platforms, or completing stripped lower receivers, the Ruger 91007 stock kit delivers genuine OEM reliability, precise receiver lockup, and smooth cycling performance.
*Armorer Bench Notes & Real-World Staging Guidance:
Fitment & Compatibility Matrix: Direct compatibility with standard MIL-SPEC dimension AR-15 lower receivers. The included buffer tube is Mil-Spec diameter (1.148"). Note: Will not fit Commercial-Spec diameter receiver extensions or rifles utilizing proprietary buffer systems (e.g., AR-10/308 platform buffer tubes without proper depth checks).
Installation & Staking Sequence:
- Safety check the firearm, ensuring the upper/lower are separated and no ammunition is present in the workspace.
- Clean and lightly grease the external threads of the Mil-Spec receiver extension tube.
- Thread the castle nut and lower end plate onto the buffer tube with the smooth side of the end plate facing forward toward the receiver.
- Screw the buffer tube into the lower receiver while holding down the buffer retainer pin and spring, ensuring the rear takedown pin spring and detent are captured properly by the end plate.
- Torque the castle nut to 38–40 ft-lbs using an armorers wrench, and stake the end plate into the castle nut notches using a center punch to prevent backing off during recoil. Slide the buffer and spring into place.
Key Features
- Genuine Ruger Factory OEM Construction: Built to original factory tolerances for reliable fitment, finish, and performance.
- Complete Stock Assembly Kit: Includes 6-position M4 stock, Mil-Spec buffer tube, carbine action spring, carbine buffer, castle nut, and end plate.
- 6-Position Length-of-Pull Adjustability: Smooth, positive position indexing accommodates shooters of all sizes and tactical gear setups.
- Mil-Spec 7075-T6 Aluminum Receiver Extension: Hardcoat anodized buffer tube resists corrosion, thread stripping, and heavy recoil shock.
- High-Impact Polymer Buttstock: Lightweight M4 profile stock features integrated sling loops and a textured buttplate for non-slip shoulder staging.
Product Specifications
- Brand: Ruger (Sturm, Ruger & Co.)
- Model: AR-15 M4 Stock Kit
- MPN: 91007
- UPC: 736676910076
- Platform Compatibility: AR-15 / AR-556 / STANAG Lower Receivers
- Tube Dimension: Mil-Spec Diameter (1.148")
- Stock Material: High-Impact Polymer
- Buffer Tube Material: 7075-T6 Aluminum
- Buffer Mass: Standard 3.0 oz Carbine Buffer
- Finish / Color: Matte Black Hardcoat Anodized / Black Polymer
