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There’s little doubt that Magpul’s innovative designs have done more to promote the idea of “tactical chic” in the last couple decades than any other company. They were one of the first to actually put some effort into designing visually appealing firearms accessories instead of simply sticking to the pre-existing military designs that seemed stuck in the 1980s. While they may have initially made a name for themselves for their visual style (and helpful mag pulling accessories), what has kept them in the spotlight is their ability to innovate and produce useful designs that solve problems. One of their latest: the ACS-L carbine stock . . .

One of the biggest complaints I read about the standard carbine style stock is how it feels. With a fixed rifle length stock, the gun feels solid and well built. The stock doesn’t shimmy or move, and it makes for a more stable shooting platform. With the carbine stock, however, the thing… well, I was going to make a Michael J. Fox joke but I thought better of myself.

The usual solution to a shaky stock is to replace it with a fixed length stock. Magpul offers the best fixed length stock in the business with their PRS offering, but it’s heavy and bulky and doesn’t work in every build. The other option is the UBR that provides the stability of a fixed stock with the adjustability of an adjustable one, but that stock is as heavy as a World of Warcraft player after a pizza and video game binge weekend. And it requires a proprietary buffer tube — the stock, not the WoW player.. If you’re looking for a drop in replacement that solves the problem with the wobble, there wasn’t much choice.

That’s where the ACS comes into the picture.


The original ACS design included two compartments along the cheek piece that increased the surface area and allowed for some battery storage, but some people (myself included) found it to be too bulky to be useful. The improved ACS-L design removes those compartments and provides a cheek piece that is closer to the other Magpul stock designs, which I like.

There are two big improvements that the ACS-L has over the standard Magpul MOE stock design: the storage compartment and the locking system.


A storage compartment is something that most people will never really need, but I find it extremely convenient. It’s not big enough to store anything substantial like a Twinkie or another magazine, but it is just big enough for some paperwork. For those using a suppressed SBR, for example, the compartment can easily fit a spare copy of your NFA paperwork. Personally, I use it mostly as a place to keep my hunting license so I don’t forget it when I head out to murder delicious animals. It can also be used for front sight adjustment tools, dummy rounds for malfunction training, or a little lube — anything you can’t afford to forget when you head out into the field. One caveat though: In the Magpul UBR the compartment can be removed, but in the ACS the compartment is permanent.

In addition to that storage compartment, the stock offers a couple sling mounting solutions. There’s a generously sized loop for a two point sling system to be anchored on the inside curve of the stock, and in addition there are multiple holes pre-drilled and tapped to accept Magpul’s QD cups for single point or two point sling systems. If you have a sling and can’t find a way to attach it to the ACS-L, then you’re just not trying.


While the sling related features are nice, the best part of this stock is that they have eliminated the wobble. In addition to the usual “push here to move the stock around” button, the stock has a second button in front of that. When you have everything set up properly, push that button into the stock and it locks up as solid as any fixed stock could. It works great, and releasing the stock to adjust it doesn’t require any special attention — just push the same button you normally do and everything works fine.

The reason I was interested in the stock was to see if it improved the already whisper quiet properties of my 300 BLK SBR. I’ve already replaced the spring in the stock with a JP Enterprises captured buffer spring and it reduced a bunch of noise, but there was still a bunch of rattling going on just because the stock and the buffer tube aren’t perfectly mated. Once I swapped out the stock, the wobble was completely gone and the rifle was just a hair quieter. In short, it worked.

The ACS-L isn’t perfect. There’s still no adjustable cheek piece, so using it on a precision rifle might not be ideal. But for those who want the stability of a fixed stock without swapping their existing carbine buffer tube, this would be my #1 choice.

Magpul ACS-L Stock
MSRP : $79.95

Ratings (out of five stars):

Design: * * * * *
I think it looks great. Functional and good looking.

Functionality: * * * * *
It works. It makes an adjustable stock feel like a fixed stock at a fraction of the price of their other offerings.

Overall Rating: * * * * *
I like it. A lot.

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    • Mag Pulls are awesome. In addition to being able to grab/pull them quickly from a pouch, they do a good job of protecting the floorplate, especially if you ‘drop free’ and let em hit the ground.

  1. I have one on my Stag Arms 3G rifle, and like it enough to put another one on a 308 I’m building. Very nice stock.

  2. My magpul CTR has no wiggle, shimmy, or slop. You close that locking lever and it’s as solid as any fixed stock I’ve shouldered. And the CTR seems to be their most basic one.

    • Totally agree. The CTR has been my go to stock for about a half dozen or so carbine builds. The locking cam sold me on it and I don’t even lock the feel of any non-locking adjustable stock anymore. The butt plate options and the ability to use cheek risers on the CTR are a plus as well.

      A little bit of storage wouldn’t be bad thing but it’s not worth giving up the riser option in my opinion. Add a riser to this stock and I’d cut my allegiance over to it.

  3. Great review. Thanks. That compartment is big enough for a couple of small camera batteries, a replacement bolt & firing-pin, and folded copy of your paperwork. I recommend using a zip-lock bag to put all of that in though.

  4. A boresnake will fit in that storage compartment. It’s where I keep mine. I have the ACS, and keep batteries on one side, and a tube of Froglube and patches on the other. That way I always have the ability to field clean the firearm.

  5. “And it requires a proprietary buffer tube…”

    Incorrect. It uses a standard A1 tube that is covered by the cam lock sleeve that attaches to the rest of the UBR assembly.

    I respect your reviews, but you really need to research before you down on a product.


      Click the “Specs” tab.

      “Mounts on durable Entry-Length Receiver Extension tube (included) to accommodate the common M4 carbine buffer and spring”

      I believe RRA also makes Entry-length tubes, but they also refer to them as proprietary as well.

      Definitely not an A1 tube, and Nick’s use of proprietary seems to be accepted as correct. Maybe an apology is in order?

      • My apologies to you and Nick. It is considered an entry length tube. A former Marine friend, my gun dealer, and Jim Fuller (from Rifle Dynamics) referred to it as an A1 stock when they saw it mounted on my AK with a Rifle Dynamics stock adapter. Jim only saw the pic I posted on his RD facebook page, so I’m sure it might have thrown him as well. Forgive my confusion.

        The A1 is apparently only about an inch shorter than the A2. The entry stock is the same length as the M4 stock completely collapsed, but rigid for striking.

        • We all make mistakes; thanks for stepping-up and correcting the record. Very hard to do for most folks, which says a lot about the honor of a person who can and does do it.

          I don’t have any personal knowledge in this area, but I suppose it’s possible that when the UBR is mounted to an AK, the overall length is comparable to an A1 stock (either due to the adapter, or the “extra” receiver length that extends behind the AK pistol grip). I have no idea how to go about measuring/comparing this particular apple and orange set-up, so the other folks you referenced may have been right on point with their description.

    • According to Magpul’s website, this comes in two versions: one for mil-spec buffer tubes and one for commercial spec buffer tubes. Sounds like you both are partially right, but in your each speaking absolutely, you may both be completely wrong.

      • The stock we are discussing, along with the referenced passage, is the Magpul UBR, not the stock being reviewed. The length of the tube is the subject, not the diameter.

        The note at the bottom of the linked Specs page, above, also states that the UBR comes with the Entry-length extension tube, so in this case, the tube diameter is completely controlled by Magpul.

        • You’re right. Between reading the article, and getting to this point in the comments, I missed the transition in reference from one component to the other, and misapplied to which the comment referred. That’s on me.

        • Easy enough mistake to make; it’s not often that folks get in a serious discussion about ONE stock, in the comments of a review about ANOTHER, DIFFERENT stock.

          And thanks for stepping up and correcting the record.

  6. …and if you don’t like/need the compartment, you can go with the Magpul STR instead. Same thing, hair lighter (and a wee bit shorter).

    For me, ACS-L and STR locked up tighter than CTR. And love that fat cheek weld.

    • Yep. Tried both, prefer the STR. I don’t suffer from ‘Monkey Arm’ syndrome 😉

      Other than that, I just stick with my CTRs.

  7. “For those using a suppressed SBR, for example, the compartment can easily fit a spare copy of your NFA paperwork.”

    Myself not having any NFA devices (yet), I thought the original paperwork / stamp had to be present with the toy. ?

    • Oh, goodness no. My original paperwork, to begin with, is not any more original than the copies I printed as soon as I got it home. It is printed out at the shop. If it were something special, it is paper and will not survive immersion, fire, etc. Original goes in safe deposit box, copies go with gun.

    • Virtually no one keeps the original tax stamp and form with the device. It’s too hard to replace if lost or damaged, and God help you if someone officially confronts you about your ownership of said item if your only copy is unavailable. A facsimile will suffice in virtually any circumstance short of an official inquiry, including casual encounters with law enforcement.

      • If you e-form it, your original is a pdf file attachment on an email. Too bad there’s no official way to tote around a flash memory device that could be used in the field by LE jic you get harassed…errr, checked. A small micro sd card could hold just about anyone’s entire collection of paperwork.

  8. Great review Nick. Always wondered why those carbine stocks were so rattly…

    The storage compartment being a bit more compact, and at the very end might help with better overall balance too, if you were storing something solid, tools, batteries, and the like, right?


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