The Magpul ACS Mil-Spec Carbine Stock (Magpul part no. MAG370-GRY) is a drop-in replacement buttstock for AR15/M4 carbines running mil-spec receiver extension tubes, finished in grey. ACS stands for Adaptable Carbine/Storage, and true to the name it offers dual, rear-accessible, water-resistant battery tubes plus an integral storage compartment in the butt for spare parts or batteries. An anti-snag release latch prevents accidental activation, while a supplemental friction lock system cuts down on the excess play some collapsible stocks develop over time. A 0.30-inch-thick rubber butt-pad gives a positive, non-slip shoulder purchase even while wearing body armor or bulky modular gear.

Key Specifications

• A drop-in replacement buttstock for AR15/M4 carbines.
• Built for mil-spec receiver extension tubes.
• Collapsible for length-of-pull adjustment.
• Dual, rear-accessible water-resistant battery storage tubes.
• An integral storage compartment built into the butt of the stock.
• An anti-snag release latch that helps prevent accidental activation.
• A supplemental friction lock system that minimizes excess stock movement.
• A 0.30-inch-thick rubber butt-pad for a secure, non-slip shoulder purchase.
• Provides positive shoulder purchase even while wearing body armor or modular gear.

Frequently Asked Questions

What does ACS stand for? Adaptable Carbine/Storage, reflecting the stock’s dual battery tubes and integral storage compartment.

Will this work while wearing body armor? Yes, the thick rubber butt-pad is shaped to provide a secure, non-slip shoulder purchase even with armor or bulky modular gear.

Does it fit standard mil-spec tubes? Yes, it’s built specifically for mil-spec receiver extension tubes.

Buy the Magpul ACS Mil-Spec Carbine Stock

Order this grey Magpul Industries stock from our AR stocks selection and add onboard storage with a rock-solid mil-spec fit. Ships fast from our Lubbock, Texas gun shop.