Magpul ACS Carbine Storage Stock – Mil-Spec AR-15 – MAG370

Click Here for Price
Out of Stock
Orders will Ship within 1 Business Day
Magpul MOE-K2+ Pistol Grip - AR15/M4 - MAG532

Magpul K2+ Rubberized Pistol Grip - Black


Magpul MOE M-LOK Handguard - Mid-length - AR15 - MAG426

Magpul MOE M-LOK Midlength Handguard - Black


Delivers Excellent Performance With More Functional Design

The Magpul ACS Carbine Storage Stock – Mil-Spec is a top-notch drop-in replacement buttstock for AR15/M4 carbine rifles that utilize mil-spec sized receiver extension tubes. Designed with dual, rear-accessible compartments, you can store extra batteries and other accessories that you may need during tactical operations.

Similar to the Magpul CTR, the Magpul ACS Carbine Storage Stock – Mil-Spec also features a streamlined anti-snag release latch to prevent accidental activation along with a supplemental friction lock system that minimizes excessive stock movement for enhanced weapon stability and accuracy.

Magpul ACS Carbine Storage Stock - Mil-Spec AR-15 - MAG370

Dual Rear-Accessible Storage For Accessories

The Magpul ACS Carbine Storage Stock – Mil-Spec is an advance and more functional approach when it comes to upgrading your buttstock on your AR-15 Rifle. The dual, water-resistant battery storage tubes and the integral storage compartment in the butt of the stock can provide multiple storage options. The storage may also help to keep your rifle well-balanced for better handling.

This Buttstock also has a sloping cheek weld that allows for comfortable shooting while at the range. It also includes a 0.3-inch Rubber Buttpad that allows easier shoulder transitions for increased accuracy.

Magpul ACS Carbine Storage Stock - Mil-Spec AR-15 - MAG370


  • Mounts on mil-spec sized carbine receiver extension tube (not included) from manufacturers such as Colt, Armalite, S&W, LMT, and others (please see the note below)
  • Sloping cheek weld provides a wide contact surface for user comfort
  • Two water-resistant battery storage tubes located on the left and right sides of the stock
  • Each tube will store up to three CR123 lithium or two AA batteries
  • Tubes are accessible from the rear via a tethered, hand-removable rubber plug
  • Storage compartment in tail of stock with positive latching access door on the right-hand side
  • Supplemental friction lock minimizes accuracy robbing wobble*
  • Shielded release latch prevents snagging and accidental operation
  • Premium chrome-silicon lock spring provides positive locking and long service life
  • Replaceable 0.30″ Rubber Butt-Pad offers an anti-slip surface and increases impact protection
  • Compatible with Magpul ASAP® and other receiver-mount sling attachments

Magpul ACS Carbine Storage Stock - Mil-Spec AR-15 - MAG370

Sling Mounts:

  • Mid – Now Includes the QD Swivel Sling Mount that fits up to 1.5″ push-button swivels
  • Rear/Bottom – 1.00″ sling loop

Optional Accessories:

  • Extended Rubber Butt-Pad, 0.55″
  • Enhanced Rubber Butt-Pad, 0.70″


  • Platform: AR10, AR15, M4, M16, M110, SR25
  • Compatibility: Mil-Spec sized carbine receiver extension tube (not included) from manufacturers such as Colt, Armalite, LMT, S&W, and others
  • LOP – M4 Collapsed: ~11.6 in.
  • LOP -M4 Extended: ~14.9 in.
  • LOP – Adjustment Range: 3.3 in.
  • Length: max 8.0 in.
  • Weight: 14.1 oz.
  • Weight – w/ receiver extension: 18.1 oz.
  • Width: max 2.5 in.


  • There are two basic sizes of M4 Carbine receiver extensions (buffer tubes): mil-spec and commercial-spec. If you have a commercial-spec extension on your rifle, make sure to order the Magpul ACS Carbine Storage Stock – Commercial-Spec – MAG371.
  • * Friction lock performance may vary depending on the host receiver extension’s dimensional tolerances.
  • ** Specifications based on standard-length (flat-back) M4 Carbine receiver extension and may vary depending on tube manufacturer.

Products available on this page:

Have Questions About this Product?

The AT3 Tactical store has a 90 day no-hassle return policy for products in good condition. You can view the full details of our return policy here.

If you encounter an issue or defect with a product after 90 days of your purchase, you can refer to the manufacturer for a warranty claim. Their policies are below.

Magpul Warranty Information

If you ever experience an issue with a Magpul product at any time, regardless of where it was purchased, please contact us directly and we’ll do everything reasonable to help you.

To make a return, please take the following steps:

  • BEFORE returning any products, please contact us first to receive an RMA number (Return Merchandise Authorization) and prominently write it on the outside of the package. Packages will not be accepted without an RMA.
  • Include a note with your name, shipping address, phone number and email, RMA number, and reason for the return (including, if applicable, information about the firearm, ammunition, and usage environment for defective returns). Do not send ammunition.
  • Wrap the item with quality padding and place it in the original packaging or in an appropriate box for shipping.
  • A UPS shipping label will be provided in your shipment. If using the original packaging, remove or cover the original shipping label. Tape the preprinted return shipping label to the outside of the box. Drop package at an official or authorized UPS drop-off location.
  • All refunds will be applied to the credit card used for the original purchase. You should allow one to two billing cycles for the refund to appear on your statement.

Disclaimer: Manufacturer’s warranty is subject to change without prior notice.

Customer Reviews

Based on 7 reviews
Christopher Rigoli
Sharp and functional.

Processed, shipped and delivered smooth and quickly.

Stock is bulky compared to others but functional. Offers a nice cheek weld as well as battery storage and “loose ammo” storage. I like the look a lot main purpose for purchasing. Complements my rifle.

Thanks for sharing your feedback, Christopher. We're glad you're satisfied with your purchase. Cheers!

John Pierce
Big John

Love Magpul products

Thanks for sharing your feedback! We're glad you are satisfied with your purchase!

Kevin Lins
Feels more natural.

Love the fast accurate smooth transaction process and that it was delivered in a matter of days. Compared to others that take at least a week for delivery. It is a more natural and comfortable feel compared to the factory B5 stock I had. Fits better and tighter in the pocket while wearing a plate carrier. The cheek rest is a little wider and the storage compartments is an added bonus. That’s makes this one far better then original I had it was money well spent.

Great review! I agree that the ACS stock feels more natural and fits better than the factory stock. The cheek rest is also much wider, which is great for comfort. The storage compartments are a great addition.

Dylan Allen

Magpul ACS Carbine Storage Stock - Mil-Spec AR-15 - MAG370

Thanks for sharing your feedback! We're glad you're satisfied with your purchase.

Greig Fahnlander
Excellent and quick service!

Items all arrived quickly and couldn’t be happier. Thanks AT3!

We appreciate your feedback, Greig. We're happy to hear that you're satisfied with your purchase! -- LM