CAA Gear Up offers a complete selection of stabilizing pistol braces, rigid shoulder stocks, modular EVO core stocks, and 1913 Picatinny rear adapters. Designed for quick side-folding storage and enhanced shooting control, these rear extension options allow shooters to configure their Micro Conversion Kit (MCK) according to personal shooting preferences and federal compliance requirements.
Review available brace and stock options, prices, specs, and chassis fitment below:
| Component / Rear Extension | Generation Compatibility | Base MSRP / Price | Primary Specifications & Key Highlights |
| MCK Gen 2 Extended Stabilizer Brace (MCKSBL GEN2) | Gen 1, Gen 2 | $64.95 | Ergonomic TPE rubber strap brace; side-folding lock button; lighter & stronger polymer design. |
| MCK Gen 2 / Gen 3 Rifle Butt Stock | Gen 2, Gen 3 | $48.99 – $49.95 | Solid polymer side-folding stock; push-button release; maximum cheek weld stability. |
| EVO Polymer Stock / Stabilizer (w/ Metal Core) | MCK EVO | $49.99 | Hybrid polymer construction with reinforced steel core; available in full or short lengths. |
| EVO Aerospace Aluminum Stock / Stabilizer | MCK EVO | $95.99 | Machined 6061-T6 aluminum construction; 8.5-inch profile; maximum platform rigidity. |
| 1913 Picatinny Rear Housing Adapter | Gen 1, Gen 2, Gen 3, Roni | $49.95 | Converts rear housing to standard 1913 Pic rail for mounting SIG/JMAC aftermarket stock hinges. |
Pistol Configuration: Feature flexible arm straps and high-impact polymer construction with integrated side-folding hinges.
Side-Folding Convenience: Locks tightly against the side profile of the chassis without obstructing the side brass ejection port or trigger access.
Rigid Cheek Weld: Constructed for maximum structural support, ideal for tax-stamped Short-Barreled Rifle (SBR) setups or when combined with CAA 16-inch extended barrels.
Push-Button Hinge: Folds cleanly to the right side of the chassis shell with a heavy-duty retention spring mechanism.
Hybrid Core Construction: Metal-reinforced polymer options provide high durability while keeping overall weight minimal.
Aerospace-Grade Aluminum Series: Premium 8.5-inch alloy units machined for heavy-use applications requiring zero flexing during firing.
Custom Customization: Replaces the stock rear housing on MCKs and Micro Ronis to provide a vertical 1913 Picatinny rail section.
Third-Party Hinge Ready: Allows direct mounting of third-party folding braces or stocks (e.g., SIG Sauer MPX/MCX braces, JMAC Custom folding hinges).
💡 PRO TIP: If converting an MCK into a Short-Barreled Rifle (SBR) by attaching a solid shoulder stock to a chassis containing a pistol with a barrel under 16 inches, make sure you have an approved ATF Form 1 tax stamp prior to installation!
⚖️ Important Regulatory Disclaimer: The state law and firearm assembly information provided in this article is for general informational and educational tracking purposes only. Firearm conversion chassis, brace definitions, NFA rules, and stock regulations change constantly, rendering online informational articles out of date quickly. CAA assumes no liability for reliance on this text. Always cross-reference your current state, county, and local ordinances before purchasing, processing, or assembling any conversion gear.