The Magpul ACS is a mil-spec carbine stock with dual onboard storage compartments for AR-15 and M4 rifles, fitting any Mil-Spec-diameter receiver extension.
The Magpul ACS Carbine Stock (MAG370) — Adaptable Carbine/Storage — pairs a friction-lock system that clamps the stock rigid against the receiver extension with dual water-resistant storage compartments in the cheek housing. The result is a collapsible stock with fixed-stock stability that also keeps batteries, spare parts and small mission essentials sealed inside the rifle itself.
The wide, contoured cheek weld surface supports precise work behind optics, the rubber buttpad plants in the shoulder, and sling integration covers loops and QD alike. For service rifles and go-bag carbines that must be self-sufficient, the ACS remains the most complete stock Magpul builds at this weight.
Key Features
- Friction-lock system: wobble-free, fixed-stock stability
- Dual storage compartments: water-resistant onboard supply
- Wide contoured cheek weld: excellent behind magnified glass
- Comprehensive sling options: loops and QD-ready
- Three finishes: Black, Flat Dark Earth, Olive Drab Green
Compatibility & Fitment
Fits AR-15/M4 rifles running a Mil-Spec-diameter carbine receiver extension (buffer tube). A commercial-spec tube is a different diameter and will not take this stock, so confirm your tube specification before you buy. Slide on, set length of pull, engage the friction lock — then load the compartments and forget them until needed.
Technical Specifications
Platform | AR-15 / M4 |
Fits | Mil-Spec carbine receiver extension |
Type | Collapsible carbine stock with dual storage compartments |
Finish | Black, Flat Dark Earth, Olive Drab Green |
Adjustment | Friction lock |
US Shipping & Support
Shipped from D&R Sports Center in the USA with fast, tracked delivery. Questions on fit, mounting or which model suits your setup? Our team is glad to help before and after your purchase.
Frequently Asked Questions
What buffer tube does the ACS need?
It fits AR-15/M4 rifles running a Mil-Spec-diameter carbine receiver extension. A commercial-spec tube is a different diameter and will not take this stock, so confirm your tube specification before you buy. Measuring the tube is the quickest way to be certain.
What do the dual storage compartments hold?
The MAG370 has two separate compartments in the stock body, so you can keep spares and small gear divided rather than loose in one cavity. It is the fuller-bodied option in the ACS family. If you would rather have a slimmer stock with simple battery tubes, the ACS-L (MAG378) is the lighter sibling.
What does the friction lock do?
The friction lock takes the play out of the stock on the buffer tube, so the stock sits tighter and feels less rattly against the cheek. It works alongside the normal adjustment lever rather than replacing it. You still collapse and extend the stock the usual way.
Which color should I choose and is anything else needed?
Black, Flat Dark Earth and Olive Drab Green are all offered. Provided your buffer tube is Mil-Spec, no extra hardware is required to fit it.
