Magpul® ACS™ Carbine Stock – Mil-Spec

(18 reviews)
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Magpul ACS Carbine Stock, Mil-Spec

The patent-pending Magpul ACS (Adaptable Carbine/Storage) – Mil-Spec Model is a drop-in replacement butt-stock for carbines using mil-spec receiver extension tubes. A streamlined, anti-snag profile shields the release latch to prevent accidental activation and the extra-power lock mechanism uses a premium chrome-silicon spring to avert auto-collapse failure by resisting spring relaxation. Similar to the Magpul CTR™, the ACS also features a supplemental friction lock system that minimizes wobble* for enhanced weapon stability and accuracy. Dual, rear accessible, water-resistant battery storage tubes and an integral storage compartment in the butt of the stock provides multiple storage options. The ACS comes standard with a 0.30" thick rubber butt-pad which provides positive shoulder purchase to prevent slippage even with body armor or modular gear.

NOTE: 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 Commercial-Spec ACS. Please see the "Related Info" section above to determine which tube you have.

Made in the U.S.A.

Friction lock performance may vary depending on the receiver extension's dimensional tolerances.

  • Mounts on military-spec carbine receiver extension tube (not included) from manufacturers such as Colt, Armalite, S&W, LMT, and others
  • Supplemental friction lock minimizes accuracy robbing wobble
  • Premium chrome-silicon lock spring provides positive locking and long service life
  • Sloping cheek weld provides a wide contact surface for user comfort
  • Shielded release latch prevents snagging and accidental operation
  • 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
  • Metal strike plate provides a hardened striking point on toe of stock
  • 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 right hand side
  • Sling Mounts
    *Mid - Optional QD Sling Mount accommodates up to 1.5" push-button swivels (NOTE: QD Sling Mount Sockets are sold seperately.)
    *Rear/Bottom - 1.00" sling loop
Optional Accessories**
  • Extended Rubber Butt-Pad, 0.55"
  • Enhanced Rubber Butt-Pad, 0.70"
  • Push-button QD Sling Mount Sockets
  • ACS, Mil-Spec Carbine Stock (w/ Rubber Butt-Pad, 0.30")
  • Weight, Stock: 0.86 lb.
  • Weight, w/ Rec. Extension: 1.16 lb.
  • Length, Stock: 7.93 in.
  • LOP Adjustment Range: 3.3 in.
  • LOP, M4 Collapsed: 11.45 in.
  • LOP, M4 Extended: 14.75 in.
* Friction lock performance may vary depending on the receiver extension's dimensional tolerances.

**Standard Rubber Butt-Pad, 0.30" weight: 0.09 lb. Optional Extended Rubber Butt-Pad, 0.55" (weight: 0.12 lb.) or Enhanced Butt-Pad, 0.70" (weight: 0.15 lb.) may be used with either Mil-Spec or Commercial-Spec ACS stocks.
***Specifications based on standard-length (flat-back) M4 Carbine Receiver Extension and may vary depending on tube manufacturer.




  • 5
    ACS Stock

    Posted by Fallujah Marine-USMC on 8th Oct 2015

    I'm a fan of these. They just feel right to me. Comfortable w/ a good cheek weld. This was my second.

  • 5
    Great all around stock.

    Posted by Myles Davies on 3rd Apr 2015

    Mounted this stock on my BCM 14.5" AR and it works very well. The battery compartments help keep my NV scope operating for long durations. Furthermore, the shape of this stock (regarding cheek weld) is the most comfortable of all the collapsible stocks I have.

  • 5

    Posted by D Livingston on 2nd Feb 2015

    Great product, quick response, fast shipping. Couldn't ask for a better experience!

  • 5
    Magpul ACS and ACS-L Happiness

    Posted by GM on 27th Jan 2015

    I scoped my AR. The ACS-L I had on it worked fine, but the ACS allows a better cheek weld for more consistent indexing.

  • 4
    Issued stock for the M110 Carbine kit

    Posted by P Eng on 27th Jan 2015

    Bought this stock for my SR-25 EMC. It came with a black SOPMOD stock (which is my preference), but wanted the stock to match the FDE cerakote on the rifle. The carbine retrofit for the M110 rifles use this Magpul ACS stock so I went with it. I ordered the mil spec one since it is going on a Knights Armament buffer tube. If you are putting it on any buffer that is not true mil spec, probably order the commercial version. The color seemed dark at first but actually matches well on the rifle. The design is a little different and I don't see why Magpul makes so many different stocks that are similar. Stock don't have much to them, so I really don't see why this stock even exists. Its not easy to put on, you need to use a real bullet to pull up the post and slide the stock on. This is the reason for the 3 stars; just an unnecessarily difficult way to install. Otherwise it seems fine, not better or worse than a SOPMOD, but the battery compartment is convenient. Its also cheap.

  • 5
    ACS is a bit heavy, but well made.

    Posted by Unknown on 12th Jan 2015

    This is purchased for a 6.8 deer rifle. The extra storage will help with extra Batts for lights, earpro, head lamp, etc. The weight will help balance an 18" ARP barrel. Love the cheek weld. SKD rocks as always.

  • 5
    Magpul ACS Carbine Stock, Mil-Spec

    Posted by James Kuhn on 26th Dec 2014

    Excellent! I haven't mounted the ACS, yet. I haven't received my new AR stick. : ) Jim

  • 5
    Love it

    Posted by Arron McGinnis on 20th Mar 2014

    Great stock. Great dealer. Even better price.

  • 5

    Posted by Richard Pond on 20th Mar 2014

    Little heavy. But overall a good stock with storage.