Magpul Industries

Magpul ACS Carbine Stock Mil-Spec for AR-15/M4

Name: Magpul ACS Carbine Stock Mil-Spec for AR-15/M4
Brand: Magpul Industries
SKU: MAG370-BLK

£115.00

VAT included.

£5 Tracked Delivery · 7–10 Business Days

Estimated delivery: Tue 8 Sep – Fri 11 Sep

Stock is imported from the USA to us, then shipped to you from the UK — we cover all duties and import charges, so there is nothing to pay on delivery.

Colour: Black

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Product Overview

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 self-contained carbine stock — the ACS locks down like a fixed stock and carries like a supply cache.

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 duty rifles and go-bag carbines that must be self-sufficient, the ACS remains the most complete stock Magpul builds at this weight.

Why shooters choose the ACS

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

What the ACS fits

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 ordering. Slide on, set length of pull, engage the friction lock — then load the compartments and forget them until needed.

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
Brand	Magpul Industries
MPN	MAG370-BLK · MAG370-FDE · MAG370-ODG

Stability, storage, sorted. Order the ACS today — in stock at Xtreme Tactical Gun Parts with £5 tracked UK delivery in 7–10 business days.

Explore more: Rifle & Shotgun Stocks, Precision Rifle Stocks, AR-15 Parts or browse all Magpul.

Compatibility & Fitment

Fits AR-15/M4 rifles with a Mil-Spec-diameter carbine receiver extension (buffer tube). Check your tube specification before ordering.

Please confirm platform, interface and fitment requirements before ordering.

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
Brand	Magpul Industries
MPN	MAG370-BLK · MAG370-FDE · MAG370-ODG
SKU / MPN	MAG370-BLK
UPC / Barcode	873750001005

Shop Related Categories

Shop AR-15 Parts & Accessories View category

Shop Magpul AR-15 Stocks View category

Shop Magpul Industries View category

Shop Rifle & Shotgun Stocks View category

Related Buying Guides

Not sure which option is right for your build? These guides break it down.

Buying Guide How to Choose an AR-15 Stock: Fit, Length of Pull & Platform

Buying Guide Best AR-15 Upgrades Under £100 (That Actually Make a Difference)

View all buying guides →

Product 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 ordering. 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 kit 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 colour 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. Other stocks worth comparing are in Magpul AR-15 stocks.

How does delivery work, and what if the fit is wrong?

This stock is sent from the United Kingdom with £5 tracked UK delivery in 7–10 business days and you'll get tracking by email when it ships. If it turns out not to match your receiver extension, see our returns policy or contact us and we'll help sort it.