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
    AMAZING Stock

    Posted by Joseph H on 29th Feb 2012

    This stock vs. the standard stock is like night and day. This thing is phenomenal. Buy it. You won't be disappointed. SKDTAC + Magpul = gloriousness.

  • 5

    Posted by Thayne Erickson on 3rd Feb 2012

    Looks great and is a perfect fit.

  • 5
    Typical Magpul

    Posted by Robert on 4th Jan 2012

    No complaints. For me it gives a perfect cheek weld to my 1-4x scope. Balances out my 18" AR well. Storage flap holds extra CR2032's for my scope plus a front sight tool. Battery tubes hold bore snake and the other side I need to find something to put in it. Maybe some M&M's or something. Lots of storage.

  • 5
    My favorite AR stock.

    Posted by Chris Citty on 15th Jun 2011

    I can't remember when/where I picked the ACS stock up, but I've had it for 4 months. It is my absolute *MUST* for dressing up an AR. It simply works so well. Magpul needs no introduction. Everyone knows their stuff is always top of the line. I've got some PMags, but I don't always use them. Depends on my mood. But my AR always has this ACS, no matter what. Solid build, dependable, rugged, doesn't rattle like some stocks do. The little compartment in the butt is great. I don't really keep anything in there, but I love the idea. Maybe some batteries or something. I love this stock, and I bet you'll love it, too.

  • 5
    Love this stock

    Posted by Chris M on 14th Jun 2011

    The Magpul ACS carbine stock is phenomenal. The lockup on the receiver tube is rock solid and eliminates rattle common in generic 6 position stocks. The cheek weld is awesome and the smooth contour does not grab facial hair as with some of the competing cheek weld styled stocks. I really like the storage options. I generally run 123 batteries in the side compartments with foam earpro between them to eliminate rattle. The lower compartment is perfect for a bore snake. PROS: smooth cheek weld, rock solid lock up, and well placed storage options. CONS: Somewhat pricey

  • 4
    great stock

    Posted by RSR on 20th Sep 2010

    Great stock and locks up very tight on my LMT MWS .308. I have never been disappointed by Magpul kit. I like it every bit as much as my LMT Sopmod stock.

  • 5
    Great Stock

    Posted by Unknown on 31st Jan 2010

    Easy installation, good cheek weld, good storage space. Strong, high quality polymer.

  • 5
    Magpul ACS

    Posted by Lars on 31st Jan 2010

    Like all things Magpul, the ACS stock wins you over initially by sheer coolness - factor. Once you get over the ACS' stylishly good looks you realize there is quite a bit of function to the form as well. The saddle on the back provides superb cheek weld to your weapon, and the streamlined design helps against snagging on your gear. Storage space is included to hold emergency spares of batteries of parts. It weighs a bit more then a standard stock, but this helps counter balance a rifle when full length rails are used. All in all the best stock I've used on my AR.

  • 4
    Great Stock

    Posted by Anthony Le on 30th Jan 2010

    The stock has plenty of great features. The battery compartment is waterproof which i like. With all the batteries inside, there is still a little room where the batteries can slide back and forth. Does add a little of a rattle to the stock, but not a big deal. The small compartment i find is somewhat pointless. it has room for a few extra .223 ammo. You can fit a small allen wrench but you'd have to fish it out once its in there. Probably only good for a small gun lube/oil kit or 5-50 cord. The ACS also has a port to attach a QD swivel, but youll need magpul's QD swivel attachment first unlike the CTR. It is heavier than the CTR or MOE stock but lighter than the UBR stock, which makes it a great stock for balancing heavier rifles. The ACS is not too heavy for a carbine style weapon and still can be used for a more SPR roll. Overall the stock is great. Has a great locking feature like on the CTR. It does what i want and i can't complain. -Anthony