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I made a mistake as a young man that I’ll share with you. As a college graduation present, I received an Armalite M15A4 from my parents. Like just about any idiot with his first AR, I couldn’t leave good enough (very good, actually) alone. I ripped the A2 style stock off in favor of some cheaply made M4 style collapsible unit. I’m not certain what my original rationale was but I know it wasn’t particularly well thought out.

The only thing that was nice about that collapsible stock was that I could adjust the length of pull for smaller shooters like my fiancée. I paid dearly for the privilege, though, by getting my facial hair ripped out every time I went to get a solid cheek weld. Not to mention the fact that it made my gun so front heavy as to become laughably impractical for all but benchrest shooting.

Enter the UBR Collapsible Stock. Besides looking unbelievably cool, its main claim to fame is the fixed cheekpiece. That’s right, you can have your adjustable stock and a consistent cheekweld too. No matter where your length of pull is set, you’ll have the same piece of smooth, beard-friendly plastic each and every time. And they say miracles can’t happen.


  • Weight, w/ Entry Receiver Extension: 1.63 lb.
  • Weight: 1.46 lb.
  • Length, Stock: 8.00-11.36 in.
  • LOP Adjustment: 7-Position (0.56 in. / position)
  • LOP Adjustment Range: 3.36 in.
  • LOP, Collapsed (M4/M16): 11.10 in.
  • LOP, Extended (M4/M16): 14.46 in.
  • Price: $265.00

Ratings (out of five stars):

Fit  * * * * *
I’ve had the pleasure of installing the M4 style buttstock before, so this was really straightforward. If you haven’t, never fear. The manual from Magpul is incredibly concise and easy to read. Everything went together with zero fuss, muss, or drama. All the pieces move in perfect harmony. There is no slack, wobble, or rattle. The whole piece is just incredibly well made. For this kind of coin, it damn well better be.

Function * * * * *

The UBR functions oh so very nicely. The length of pull adjustment is crisp with a nice audible snap. When you have it locked, it stays locked. I beat it against some rocks and the bed of my truck in the hope that I could break something, but I was met with no success. The UBR is hell bent for stout. The fixed cheekpiece is a godsend. I’ve never been so comfortable shooting my AR.

Accessory Integration  * * * * *

The UBR has reversible sling swivel attachment points and a nifty little storage area. As you can see, it can hold a good amount of chocolate gold coins. Batteries, a few extra bullets, or a spare firing pin could probably go in there too. For future reference, gold coins are preferable for your humble scribe. You can also add an aluminum strike plate in case you wanted to perform “various breaching operations as well as Close Quarters Battle butt-stroking maneuvers.”

Huskiness  * *
The only place where I can fault the UBR is in the weight category. Holy fat lady, this thing is heavy. Once installed, my AR went from a chunky 7.5 lbs. to an even chunkier 8.5 lbs. with just irons installed. Throw a scope and rings on it and we might be looking at a 10 lb. rifle. For benchrest shooting, that isn’t really a concern. But if you were looking to build a lightweight carbine, I’d look at another one of Magpul’s buttstocks.

The UBR just weighs too much. I might try to muscle it around a competition at some point just to say I’ve done it, but this modification pretty much cements this gun’s status as stationary scope tester.

Overall Rating  * * * * 1/2
For what I do with this AR (stationary shooting), this is the best of both worlds. I can have a consistent cheekweld and still adjust the length of pull for smaller shooters or for bulky winter clothing. There is no doubt that the UBR is well-built and will most likely outlast me. However, if I were building out a M4 style AR, this wouldn’t be my first choice. It’s just too heavy. Give Magpul some time and I bet they come up with a lighter version. This is design is just too cool to not get some R&D tweaking.

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  1. I’ve got them on all my AR’s now and have not found the extra weight to be a hinderance. I use them for three-gun competition as well as training. Three EAG, three Rogers’ classes and numerous matches in the last three years and I have no complaint at all about the weight. I don’t even notice it.

    • It’s all about balance. If you’re running a light front end, you’ll notice the UBR quite a bit. But if you’ve got a rail system pimped out with the latest gadgets and optics, well, the UBR balances it back a little nicer. It’s not hard anymore to dump a pound of gear on the front of your gun…

      The question in my mind is more “are you willing to pay one pound of weight for the toughest, most flexible, most comfortable AR-15 stock?” It’s a very subjective question, with no right or wrong answer.

  2. I saw one of these in a used bin at a gunshow last week for $100, and I would have jumped on it…BUT I’d just spent $70 replacing my AR’s suck-tacular M4 stock with a fixed A2.

    The M4 stock made the gun extremely front-heavy (just as yours was) and now the balance is perfect.

  3. I’ve got it on an already pretty heavy POF P308, but boy does it balance a lot better now with the UBR. If you put it on any of the AR-308’s you might just find that those front heavy beasts are a little bit more tame after the change.

  4. Ugh. I die a little inside everytime I see someone who is supposed to “know about guns” holding an AR with the stock fully extended and with their hand just in front of the mag well. And they are almost always bladed to the target.

    • No need to die inside! If you ever come to Austin, I’ll be happy to pay your range fee and our bar tab afterwards to work on my stance. I’m completely self taught when it comes to holding an AR, so there are some obvious deficiencies.

      Maybe its time to sign up for that defensive long gun class in my neighborhood….

      • I know this was from a while ago, and I hope you’ve had the time and opportunity to do more shooting. As a fellow fan of Magpul, I would suggest that you (or any other shooting looking to better themself) look into the Magpul training videos, specifically, in this case, the two on the carbine. There is a lot of knowledge to be gotten from them.

  5. I have 3 AR stocks, My POU has me packing the lightest/compactest rifle possible I like the M-4 type stock, it lets me adjust LOP to fit my load-out which varies from a IIIA to a full blown plate rig over insulated clothing. I also need the shorter OAL getting in and out of vechicles. I don’t notice facial hair getting caught in the stock and I really don’t need a stock that should be hung alongside of fishing lures in the sporting goods store. There is a place to store your poggie bait and it’s not in a stock, it’s at home. There is also a place to store your extra batteries, ear plugs, MP3s et al. not in a stock.

  6. Your review on the Magpul UBR and the fact that it does look pretty cool, has made me cough up the $250 for the stock, and I love it! Very sweet addition to my AR15/M4orgery..



  7. Great review! I love the UBR stock. I ordered my Hera Arms AR15 with one of them (one of the last ARs that they sold with the UBR, just because Magpul stuff is damn hard to get here in Europe. CTRs not so much, but the UBR is almost impossible to get these days).

    I like the balance of it, even though my AR has a 14,5″ barrel with a 9″ handguard. Wouldn´t want any other Stock.

  8. I was thinking about trying to adapt this stock to my PTR-91. HKParts sells an adapter that looks like it’ll work. Anyone tried this?

  9. Gotta say I love the UBR. Been running one on my AR-15 for a few years now and honestly plan to replace all my other butt stocks with the UBR over time.

  10. I have 2 of em, love them! For some weight savings id recommend the ergo f93. Its the original version of the ubr, sold to ergo. Not quite as good of a lockup, but you get the solid weld and weight savings!

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