Magnesium AR15 Lower Snaps In Epic Fashion

Thumbing through my Instagram feed a few weeks ago, I came across an interesting post by our friends at The Armory Blog. Originating at the sub-reddit r/3gun, the above image is a MAG Tactical aluminum and Magnesium hybrid lower which was originally advertised as being ‘ultra-light weight’. I’ve used the past tense because the company is now apparently out of business – judging by the numerous internet reports of material failures, we may have an idea of why.

I am not a materials engineer, however brief “internet research” shows that some magnesium alloys are used in aircraft manufacturing and other load-bearing critical applications. If I had to take an uneducated guess, the MAG Tactical lowers needed a little more science before heading to final production.

Information on the failure and a link to the source thread can be found below.

‘Complete Failure’ OF Magnesium Lower From the Reddit Thread at r/3gun:

Slowknots:

Not my rifle. But it happend right infront of me. Shooter engaged targets without issue. He noticed his stock was wobbly. he looked down and saw a crack.

He stopped shooting and when he went to unload – the whole rear came off.

No evidence of bad ammo. Grain structure doesn’t look torn. Just looks broke off.

Its an aluminum / magnesium receiver which is the likely culprit.

Did make everyone pucker!

Magnesium

Mag Tactical Lowers From Classic Firearms (Out Of Stock):

Ultra-light proprietary magnesium alloy from Mag Tactical has their AR15 lower receiver being 35% lighter than standard lowers on the market today. Not just looking to be the lightest on the market Mag Tactical Systems reinforced key areas of the receiver including the front pivot pin location and the trigger and hammer pin area. Longer trigger pin set included. Premium Grade, Ulta Light Weight Lower.

Credit: Classic Firearms

TFB’s Ray I. Posted about MAG Tactical about four years ago:

Mag Tactical System constructs them out of a proprietary magnesium alloy and also uses a proprietary coating process to protect their lowers from corrosion. It features an integral trigger guard with room for winter gloves, a reinforced front pivot pin, reinforced trigger and hammer pin axis points and also includes extended trigger and hammer pins.





Pete

LE – Science – OSINT.
On a mission to make all of my guns as quiet as possible.
Pete.M@staff.thefirearmblog.com
Twitter: @gunboxready
Instagram: @tfb_pete
https://www.instagram.com/tfb_pete/


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  • Gus Butts

    Reminds me of that one company that made polymer lowers that would break in this fashion that kept changing names and scamming customers over and over…

    • burningwar

      Did polymer lowers ever get sorted out? I’ve always wanted to have one for a lightweight build.

      • BattleshipGrey

        I could never tell if the problem was with the polymers or the companies making them.

        • Gus Butts

          Yup back in ’09 I ran matches for a whole weekend in Texas with a Cavalry Arms rifle and it is incredibly light weight and comfy. They are a unique design in that the entire lower is made of one piece with an A1-length stock with the integrated receiver extension inside, which is in part why it’s so strong and doesn’t snap in half. 10/10 lower.

          • Timmah_timmah

            Yup. Cav Arms / GWACS is the most durable polymer lower by far. Because it was designed with the material in mind and is much thicker around the receiver extension. Aluminum and polymer simply do not possess the same strength. Any competent engineer knows you must work in this way. Why would anyone think a polymer lower receiver modeled exactly after an aluminum version would hold up to the same stress levels? That’s stupid.

          • RetroG

            Because they do it going from steel to Aluminum, even though Al has inferior stress/strain characteristics and eventually fails early compared to the steel frame.

      • Audie Bakerson

        The Cav Arms/Gwacs one is apparently good, but it’s a very non-traditional one.

        • Flounder

          That is the one I was talking about!

      • Jtx

        New frontier makes a pretty good polymer lower I’ve had one for 7 years now without a single problem i think because the polymer is molded into shape instead of milled like other company’s, I’ve been through quite a few other polymer lowers like plum crazy, poly 80(gen1), and some other really crappy companies which all broke in different places within 2 years. I also have a poly 80 gen 2 lower that so far has been pretty good but not great if you don’t want to mill your own

      • Rick O’Shay

        I have a couple of polymers that have been decent enough to not fail in that particular area. Instead, my issue has been with the FCG pin holes, to where I kept getting “double tap” type shots. Drop-in triggers fixed the issue. We never could figure out why the holes were out of spec. It was concerning enough that all the polymer lowers are now relegated to the back of the safe. Aluminum lowers can be had cheaply enough that I can’t really justify buying or using polymer lowers. What I’ve got now are truly SHTF-scenario lowers.

        • Flounder

          They aren’t out of spec… Unless these were 80% lowers you made and were off just a little bit. The holes are probably wallowed out a little bit. I mean, you are rubbing steel against polymer evertime you pull the trigger. The holes are gonna wear out eventually.

          OR, you could just be compressing the polymer (which has way more flex than any steel or aluminium) to the point where the trigger pins are so far out of alignment that the fcg no longer interfaces correctly.

          • Rick O’Shay

            They weren’t 80s. The manufacturer couldn’t figure out what was up with it, and replaced it. I suspect it warped or distorted somehow.

          • Sunshine_Shooter

            ‘wallowed out a little bit’ = out of spec.

          • Flounder

            I mean by use by you… not a manufacturer defect. It is a common enough problem for ALL polymer lowers.

            And since we are talking about problems! The polymer lowers biggest problems are
            -pin holes wallowing
            (The trigger and hammer pins)
            -snapping in half
            (Usually around the buffer tube or through the rear takedown pin hole)

            I guess they are easy to cross thread as well so metal threads are nice. But this is a much smaller issue.

            If a lower is not reinforced in those places it will break very quickly. As in sub 5k rounds.

      • Bradley

        The Kizer receivers seem to show some promise. I haven’t seen detailed third party testing, but the info available seems good. They have aluminum inserts for the pin holes and buffer tube threads.

        • Flounder

          Arent they brass inserts? But the reinforcement is in most of the right places. Pin holes and threads. My problem with them is the price makes them way more expensive than forged revievers and only an ounce or two lighter? Just get a lower that has been “lightened” like the 2A armament ones… or without the forward assist. And the kizer ones only come as a set last time i checked.

          • Bradley

            They might not actually be aluminum. I haven’t looked at them in a while. I’ll have to check the weight, but it seems like it was several ounces between the set. I’m not promoting them. It’s just that I haven’t really seen any reports of failures or problems other than a picture of a cracked dust cover. They do seem expensive, but they are still about half the price of any good ultralight metallic receiver set. Personally I would like to find an affordable upper with no forward assist that is otherwise full featured. That is a decent amount of weight for something I have never once used.

          • Flounder

            This post is too long. I hope it helps. Or is at least worth the read.

            Anderson has a upper reciever without the FA cheapest and will work but is mil spec in every other way. I recommend this just behind the DSA, they are the same weight but this one looses some function, but is much cheaper 50ish MSRP I think.

            DSA makes a very light one WITH the FA… I have actually had to use it a few times, but that was related to other parts breaking so it is not quite fair, but if you are desperate enough, and parts are broken, I guess the FA is useful in keeping your AR running like a bolt gun. I have the dsa on another rifle and it saves you an oz or two over mil spec. I also don’t think it compromises strength in anyway that is meaningful. So This is my overall recommendation. It should be under 100, and light, and 100% functional.

            A note here, EVERY time you go to a lighter part you make it more fragile. You can mitigate it here and there, but watch out! Otherwise, you end up having an article like this written about you.

            Bootleg makes an upper reciever without a FA it is the best in price/weight ratio. And is one of the lightest it saves an oz or two over the anderson I think.

            2A armament makes the balios lightweight ones. These are the lightest on the market I believe… I know they are when combined. But they are like 4-500 for the upper and lower and are just too expensive for me.

            I think BAD makes an upper reciever without a FA, I know they make a lightweight one. I have no experience with it.

            Mega makes one… That is my favorite but hard to find and pricy, but they make a matching lower for it, this is if you have money to burn and want the “neat” factor of some cool milling on the recievers. I wanted something else as my lower, and so I got the bootleg upper to go with it.

            But… Strike industries makes an aluminium FA, and a polymer dust cover (that you can install without removing your barrel nut) and there are Titanium trigger/hammer pins and Titanium takedown pins (I wouldn’t use alumium there because it is so much weaker than steel, but aluminium pins exist and are a touch lighter than Titanium parts as well as much cheaper)

            I guess what i am saying is that you gotta be crazy to try to reduce the weight sooooo much you are taking it out of the recievers. At some point, the gun becomes too fragile to use. Although, competitors seem to do it and run their guns perfectly in competitions.

            I also think you misunderstood my point, or I was not clear. The lightweight Aluminium recievers (the billet ones) in the price range of the kizer are the same weight, but much stronger, The more expensive ones like the 2A armament are lighter, by an ounce or so and probably much stronger as well.

            The real point is, the kizer is neat… but there are products that are better in every way.

        • Note where THIS rifle broke. The fact that your pin holes aren’t egged and your threads aren’t stripped is irrelevant when the whole buffer assembly falls off.

      • Jared Vynn

        TNARMSCO has a nice polymer hybrid that has brass inserts in a few areas and a great warranty.

        • Timmah_timmah

          Call me crazy, but I really don’t see how a thin brass thread insert makes up for the strength difference between ALUMINUM and polymer which can be bent by hand! (This coming from a guy with a polymer lower *for my AR22*)

          • Jared Vynn

            They use a fiber filled nylon for their lowers and it is fairly strong stuff, and lowers aren’t subject to a lot of abuse compared to other parts like the BCG or Upper. However the brass inserts are for the threaded portions such as the pistol grip screw and castle tower, this drastically improves durability in some of the higher stress areas and they also beefed up their lowers compared to aluminum lowers to make up for the difference in strength.

          • Timmah_timmah

            Sorry man, still not buying it. The Cav Arms/GWACs lowers are “beefed up”. TN Arms not so much. Look them up and you’ll clearly see what I mean right away.
            Is reinforced polymer better than polymer without reinforcement? Sure. But still nothing like aluminum. You know, metal.

          • Jared Vynn

            I don’t have a GWAC lower on hand to compare on how beefed up they are compared to each other, but I can tell you it is more beefed up than a normal aluminum lower. However unlike the GWACS you can use different pistol grips and stocks rather than both being fixed as part of the lower.

            Look up tnarmsco and you will largely see positive reviews as well as great customer service. You can also read a lot about their design work on their posts and comments on Reddit. They have a great 308 lower and Glock magazine lower, something as far as I know GWACS doesn’t have.

        • Seen ’em break, just like every other polymer AR receiver design I’ve seen (except the Cav Arms and their descendants).

          • Jared Vynn

            I have seen a tnarmsco lower in 308 breaj, but I also saw them replace it no questions asked. I have also seen aluminum lowers break.

            Cav arms may not suffer as many breakages, but you lose modularity in trade.

      • Independent George

        GWACS Armory has one, but with a fixed stock and grip. According to them, that’s the only way to make the rear of the receiver strong enough to handle the reciprocating buffer, which makes sense to me – if you change materials, you also have to change the dimensions due to the different properties.

        In practice, using an MFT minimalist stock cuts about as much weight as the GWACS lower, so I don’t know that it’s worth it (especially because I hate the standard grip angle).

        • int19h

          I suspect GWACS/CavArms might actually be more durable than a conventional lower + buffer tube + MFT stock, especially if you mortar it a lot.

          • John Paschke

            “especially if you mortar it a lot” – if you do you’ve got bigger problems than worrying about an inexpensive lower

      • Jeffrey

        I have a poly lower on my AR in 7.62×39. I have about 2000 rounds through it and it’s tight as a drum.

      • Flounder

        Only one… InrangeTV did a bunch of reviews on them. They are monolithic, as in lower, pistol grip, and stock are all integrated. Like made in the same mold at the same time. So all three are one piece.

        I have had three polymer lowers. That one is the only one that works. No lower that is the same size and shape as an aluminium lower is going to be able to provide the strength needed to perform it’s function.

        They are always weaker, and you really need to change certain dimensions to get them to a point they won’t fail.

        Another thing, you are never making significant weight savings in the lower reciever by going to polymer except for one lower. I think it is the tegra arms one… It is like 3.5oz vs the standard of 6oz-ish of a forged.

    • Twilight sparkle

      Are you thinking of Hess, Blackthorn and Vulcan?

      • HairSplitter

        I think it was spelled “Hesse,” but I like to split hairs.

      • Gus Butts

        Yes! Those are the ones.

        • mazkact

          Hesse’s biggest foul up was cast aluminum receivers. One of my best shooting AR’s has a Blackthorn upper.

  • BattleshipGrey

    At least he’ll be able to salvage the internals on the lower for his next one.

    • Anonymoose

      His next one will be a GWACS. :^)

      • Risky

        I love my GWACS! The ultimate AR15 tupperware. Forgotten Weapons has a been working on a nice set of videos featuring some GWACS builds called WWSD (What Would Stoner Do).

        • Timmah_timmah

          That WWSD series is pretty interesting. (Clint at Thunder Ranch follows similar principles with his rifles, albeit dialed back a little. Less is more. Light as possible.) Modern metallurgy and mfg processes have really made lighter barrels and lighter rifles a real possibility without risking reliability in all but the absolute worst circumstances.

      • Sunshine_Shooter

        GWACS might actually work, though. The stock is molded in, so you don’t have the stress-focusing buffer tube adapter that destroyed my poly receiver.

        • Flounder

          I have about 1500 rounds through mine thus far. No problems or anything. Which means it beats my two other polymer lowers out. By more than 1000 rounds.

          It is also much lighter than your average assembled lower. I dont have exact numbers for you though. There is a 3.5lbs build that used it out there though.

          • Sunshine_Shooter

            1500 rounds beats my old poly lower that snapped by about 1400 rounds.

      • Timmah_timmah

        Good call sir

  • RavishedBoy

    Lower and lower quality…

    • Dr. Longfellow Buchenrad

      I see what you did there

    • Carlos Velazquez

      Great!!!!!! I just finished a build using one of these lowers.

  • Jtx

    Mortar charged his rifle one too many times, suprise suprise you broke it.

    • Timmah_timmah

      Do we know this to be fact? Or you just poking the guy while he is down?

    • Adam Morgan

      This gun has NEVER been mortared. just FYI

  • Tim

    All this “My 6lb. rifle is sooooooo heavy, I can barely walk to the cheetos”. You ladies do this to yourselves. Now your nails are ruined.

    • Flounder

      I am working on a 4.5lbs rifle… Just for fun. My others are 5-8 lbs. But one got past ten because I wasn’t watching the weight and it got porky pretty fast as in over 10lbs.

      It was as much a mental exercise/learning experience as having something awesome.

      But the reciever is one of the absolute LAST places you should take weight out. It is extremely hard to make significant gains in any way without seriously compromising the reciever’s strength.

      Weight in the back makes the rifle balance better. Front heavy rifles suck as much as a heavy rifle.

      • Timmah_timmah

        “Weight in the back makes the rifle balance better. Front heavy rifles suck as much as a heavy rifle.”
        YES! This should be in everyone’s mind when conceptualizing a lightweight build. I never understood the recent obsession with these superlight minimal buttstocks. If any part of a lightweight rifle should be “overweight” it is the stock! Balance is critical and has more impact on use than simple total weight.

        • Flounder

          Well… you are right. But the stock is one of the heaviest parts and one of the only parts you can aave money and weight by going minimalistic. And doing the lightweight build… sometimes i got a little lost or excentric trying to cut weight. It actually made me rethink the whole project and redo some things. I will probably end up with the ACS stock which is 14oz. And maybe another lighter stock that sits in the closet when someone actually wants to weigh it. Lol

          The thing that drives me crazy is everyone wants a minimalistic stock and a freaking 15″ rail and make the rifle balance somewhere front of the barrel nut!

      • xx

        Actually, the problem is, the receiver is designed with a certain material in mind. There is an all polymer lower that has the stock and pistol grip built in, which prevents this type of failure from happening, and in many occasions is actually stronger than a mil spec lower. It’s made by GWACS and it was tested by Ian who runs the channel forgotten weapons over on youtube.

        • Skyking60

          Flounder, those polymer lowers with the grip and stock built in, from their original company; I have several. One registered as an SBR had a different failure – The polymer split at the top of the opening where the buffer goes in. It didn’t fail the same as that picture above, but it was just as much a failure. And talk about a headache. I’ve had that lower sitting on the shelf for several years because I can’t find anyone that knows how to repair it with the original company no longer making them… 🙁

          • AlbertOneStone

            Skyking, Have you tried contacting GWACS Armory about a possible repair method?

          • xx

            Isn’t GWACS armory making them? They are still for sale on their website.

      • dc

        2001. Professional Ordnance Carbon 15- 3.9 lbs from the factory.
        been there done that.

    • Timmah_timmah

      Haha last I checked, the great selling point of the Armalite platform is its modular design and ability to be modified and configured however the user desires. Sorry we can’t all be super badass like you bro.

      • Tim

        Wow, the first genuine female at TFB. Welcome.

    • HSR47

      The reason that many people want their rifle (by itself) to be as light as possible is that modern conveniences (lights, optics, mufflers, etc.) add weight.

      Sure, there are some people who take it to the extreme and try to keep their complete rifles under 7 pounds loaded, but most of us just want to keep our rifles in a more respectable 8.5-11 pound range. You know, the same weight as an M1 rifle, or an FN FAL.

      We’re not weak, we just don’t want to be lugging around a 15+ pound rifle.

    • Alex Brown

      My school of thought is that a 5lb workaday reliable rifle is a best practice if your accessories would have made a normal setup 11lb+

  • Anonymoose

    Mag Tactical has been out of business for a couple years now.

    • Phillip Cooper

      Did you read the first paragraph?

      • Anonymoose

        He said “now apparently out of business,” I was adding to that, since they were dead and forgotten a while ago until Pete here dug them up. Mag Tactical made a lot of noise on youtube and review sites, but never sold that many units and keeled over within like a year of opening, and then tried to sell off all their remaining receivers in bulk.

    • Timmah_timmah

      That is true. Now Fostech is selling these same lowers! They just don’t seem to go away.

    • Flounder

      They are still kicking around and available. Someone bought them and got rid of the mag tactical name. Guess too many magnesium lowers broke.

  • A.WChuck

    “With great lightness comes great responsibility.” -Aunt May

  • Phillip Cooper

    I’m always syrprised at the fact people go for ultra light receivers for the M16 family. It’s an aluminum casting, that is plenty light already.

    But then, you’ve got weight weenies that will pay $5000 for a set of carbon fiber wheels on a bicycle. “A Fool and his money are soon parted”.

    • BillC

      No, it is not an aluminum casting. They are forged and then milled. Completely different. You have no idea what you are talking about.

      • Phillip Cooper

        Actually I do, but misspoke. Thanks for that.

        I assume you’ve never misspoke, right? How wonderful that must be.

        Have a great day!

        • Beju

          It is wonderful, thank you.

          • Phillip Cooper

            Keep trying.

  • Gee

    This is what happens when you try to make your rifle a featherweight. You can’t stop physics.

  • Veteran for Trump

    I for one am not concerned about weight as I use a bipod and the heavier the better for less recoil. My suppressed 5.56 AR with scope weighs in at 10.75 pounds empty. But if I was to want less weight and could afford it, a Titanium lower would be my choice.

    • iksnilol

      But titanium weighs more than aluminium.

      • Timmah_timmah

        Correct. Cracks me up how few people understand that fact.

        • RetroG

          It is also stronger per unit weight than Aluminum (or steel), which means you can use thinner walls, etc., and retain the same strength. It resists deformation, but doesn’t resist wear as well as Al or steel, which means wear surfaces have to be coated or hardened.

    • Sunshine_Shooter

      Considering the original post comes from r/3gun, your philosophy is completely different than the one that drives the broken rifle’s owner.

      If he were to use a 10 lb, 9 oz gun in competition, he would have terrible target transition times, over-drive the targets, and lose valuable time for almost nothing.

      • Porty1119

        I am completely unable to understand 3-gun. It’s a game, and not even a cool or characterful one like CAS.

        • Sunshine_Shooter

          I’m unfamiliar with CAS.

    • Timmah_timmah

      Sure. Use should drive your design/build. If you can afford to post up on a bipod, go right ahead. However, the main intent of the original armalite design was for a highly portable infantry weapon. It was conceived with light weight as a goal from day one.

  • Edeco

    Aw. I always like seeing new materials. It would have been neat if it had worked better.

    Focusing on the cost/benefit is arbitrary and myopic. Looking at the Chevy Vega one could click ones tongue about aluminum engine blocks, say they were trying to profit by replacing iron with crap-metal, trying too hard to save weight. How dare they, right? But it turns out Al works for engine blocks.

    • Independent George

      New materials are fine, but the machine has to be engineered for the properties of that material. Usually, you can’t just replace the material and keep everything else the same without some sort of compromise – if they had the same properties, they wouldn’t have different densities. And if they change the dimensions, then it likely would no longer be compatible with various aftermarket parts (which is one off the main selling points of an AR).

      For example, the GWACS polymer lower is thicker at the structural points than a milspec 7075 lower – it still saves weight and is stronger than a standard receiver, but it’s but it no longer has the same dimensions. As a result, it requires an integral fixed stock & grip, and I believe it has its own takedown/pivot pins as well.

      • Edeco

        Huh. The Mg company said they reinforced theirs. Not enough apparently, unless the crack is due to porosity or abuse or something. By your own example switching materials, reinforcing and maintaining compatibility can be done.

        I don’t know if you’re saying it’s impossible to do an AR15 lower with Mg. I don’t think this proves it impossible. I don’t think there’s enough data on Mg yet for a meaningful comparisson of its success rate compared to plastic.

        • Independent George

          I’m not saying it’s impossible to do an AR lower with Mg; in fact, I think it would be very desirable. I’m saying that it’s impossible to do an AR lower with Mg that keeps the exact same dimensions, while still holding the same durability.

          The Mg alloy is going to have different physical properties from the Al, just as 7075 is different from 6061. I would love an Mg lower, but don’t want to sacrifice strength; therefore, it will likely need to be thicker in places, which means that it will likely not be compatible with all other milspec parts.

          It’s all about tradeoffs, and it looks like Mag Tactical gave up durability in favor of compatability. That’s not to say this is necessarily bad – I’ve deliberately selected a weaker (but lighter) handguard on my upper – but it’s something that should be acknowledged to the user.

          • Edeco

            Ah. I’m not worried about the exact outside shape or longer pins. I doubt any company would try to sell one that couldn’t take standard mags and trigger groups

        • Samuel Millwright

          There are multiple companies out there working on a new form of stainless magnesium but they’re all kinda stuck on this one minuscule little sticking point…. I mean outgassing cyanide if it gets too hot SOUNDS worse than it really is right?

          • Edeco

            Maybe… how much cyanide, what kind, and at what temp? This smacks of paper tiger.

          • Samuel Millwright

            We should definitely hang out some time!

            I hear things like outgasses cyanide and I’m like pffft… I worked at a tire recycling plant in Arizona one summer, is that supposed to scare me?

            Truthfully though It’s straight up hydrogen cyanide gas and apparently in sufficient amounts to be pretty lethal. But they’re working on it and i got the impression that they at least have a pretty decent roadmap to not accidentally gassing people.

          • Edeco

            Indeed, yikes rubber fumes . Yeah it’s funny the stuff people worry about. Like they look at the hazard but not the exposure. Like “oh no, lead”. Of course that’s probably no big deal if it’s in metallic form, just don’t dissolve it and drink it. Same thing with guns, spectacular hazard but pretty easy to avoid exposure.

          • Samuel Millwright

            Yeah, i mean i guess with as poor as most education systems seem to be these days i can almost see the merit in the better safe than sorry mindset over the much more unfriendly to mistakes risk management mindset.

            Unfortunately the better safe than sorry mindset is actually extraordinarily dangerous and often downright lethal if you try to apply it to things which it shouldn’t be applied to like combat!

            Some things are inherently unsafe no matter what precautions you take though!

            This is where risk management and an educations biased more towards practical application of knowledge in real world environments over rote memorization really shine!

  • RSG

    Wasn’t Mag Tactical bought out? I believe I’ve heard that in multiple videos, the last one being talked about on IraqV8888’s channel.

    • Timmah_timmah

      Fostech has rebranded these lowers

  • Rock or Something

    “Leopard geckos also have the ability to voluntarily detach their tails if it is attacked, grabbed by the tail, bitten during copulation, or nipped by another during feeding. This is called caudal autotomy. After autotomy the tail can continue to twitch for as long as 30 minutes, allowing the gecko to escape from its predator.”

    • Samuel Millwright

      You just won the internet today with your comment which was either horribly misplaced or a level of “stick my d*** in your ear and f*** with your mind” sadistic that not many people can even comprehend much less emulate!…

      Either way, you keep being you bro and don’t let anyone pull your tail off!

      • Timmah_timmah

        Uh I get it. Not that funny, but not that abstract either.

        • Samuel Millwright

          Maybe I’m just crazy enough to really like random stuff like that….

          *shrugs*

          This would not be shocking in the slightest honestly.

    • Porty1119

      You win. I don’t know what you won, but you won it.

  • James

    Hmmm. This reminds me of Dwight Williams and his ultralight almost-as-strong-as-steel aluminum FAL receivers.

  • Kirk Newsted

    Maybe I’m just crazy, but my standard aluminum lower seems to be just fine. Its already light enough.

    • Edeco

      Lightness is basically a more-is-more thing though; if there were a 4lb AR that performed the same as a current 7-pounder for the same price people’d be all over it.

    • HSR47

      Most of all, I don’t understand why it isn’t more common for companies to just mill out the FCG pocket to full M16 spec; That’d shave a bit of weight off without compromising the structural integrity of the receiver in any way — that’s the way the guys with the sliderules designed it to be made.

  • PeterK

    Whoof. I almost bought one of the newer ones at classic firearms. Glad I went aero precision instead.

    • Timmah_timmah

      Yeah heard that

  • Arie Heath

    I just use the GWACs polymer lower. Works fine for me, and I’ve shot a few thousand rounds through it so far. The darn thing is durable too, but you give up an adjustable stock.

  • tsh77769

    The Cavalry Arms and GWACS (bought Cavalry Arms design) lowers are 100% good to go, durable as hell, and awesome. I did prototype testing for them back in the early 2000’s and still have prototype # 6. Their design is unique and does not allow for the stock to be changed as it is beefed up and integral to the receiver. So, you get stuck with not changing the stock, but it is hell stout. It is the only ultralight lower worth talking about as far as I am concerned. It saves not quite a pound over a conventional build depending on configuration (fixed stock vs fixed stock anyways).

  • Some Rabbit

    That’s the quick detachable stock feature.

    • Sunshine_Shooter

      It’s free to collapse, but $200 to extend.

      • * $30 plus an FFL fee to extend. Anderson lowers come free with purchase of a cube of budweiser now.

        Or $26 for a 7075 80% cerroforge lower at any of 3 places that come to mind.

  • Timmah_timmah

    Dang. There’s yer problem right there, buddy! In all seriousness, I am glad no one was injured. I have seen these Mag Tactical magnesium lowers also marketed/branded as Fostech recently. Would love to know if they actually improved the product or simply relabeled it.

  • Timmah_timmah

    Saw that as well. Curious if they actually changed anything or just slapped their name on it.

  • Some Guy

    >Try to make 1:1 copies of parts in different materials
    >fail

    Why is this so common?

    Do companies just not have engineers (or just someone who dabbles in basic physics)?

    For that matter trying to save weight on your AR by making the receiver lighter is like a fat person trying to lose weight by switching to diet coke.

  • Scott Couch

    A lower in itself is pretty darn light. It’s all the crap people ad to an AR that give it weight. There’s this infatuation with making weapons so light that you compromise in the strength and accuracy department. Put your big girl panties on and carry a freaking rifle.

  • LazyReader

    Guessing they got the recipe wrong, magnesium alloys are quite the durable use in aerospace..what did they do wrong

  • jerry young

    I just don’t get the light weight frenzy, everything is about cutting a few ounces and then you put lights and scopes, lasers and bipods plus a multitude of other unneeded doodads that increase the weight far beyond any reasonable amount then complain my rifle is too heavy.

  • mazkact

    Because aluminum is too heavy ???????????

  • Sledgecrowbar

    Maybe “Epic” fashion isn’t the right term for how this failed. It’s the well-known-weakest point in the AR-15 lower receiver design. It doesn’t fail much at all in aluminum receivers, but if you’re talking about the more-recently popular plastic receivers, and then it fails all the time.

  • Ark

    They tried to fix something that ain’t broke.

  • Arizona Don

    I haven’t thoroughly checked the previous threads and am a little late to the discussion but here’s my 2 cents, in a somewhat different direction. I’ve built a decent amount of ARs in my years and have noticed a problem with some ‘discount’ parts which may account for this ‘break’. I have purchased parts from some non-gun type vendors and have noticed obvious, incorrect dimensions on the AR15 receiver extension tubes/buffer tubes. The inside length dimension of the tube should be approximately 7 inches,plus or minus .10. Some I have purchased have been as long as 7.5 inches (AR10 extension tube?). If an AR15 builder were to assemble a rifle with one of these out-of-spec tubes and fire the rifle, the ‘key’ on the bolt carrier would ‘violently’ contact the lower receiver (area below the charging handle). Since the cycle velocity of an AR bolt carrier assembly is quite high it would not take very many impacts to cause damage to the receiver. This may not be the case in this instance but I have built enough cheap aluminum or polymer receiver rifles and pistols and have not had a failure such as this. But then there’s always tomorrow when my luck runs out.

  • Chris Gonzalez

    fostech bought out the patent and is not selling these also they are cheap 37.50 at classic fire arms so I may pick one up and see how well it holds up………………..

  • go4it

    Hilarious! I guess this only proves that any idiot can break a bowling ball – or even an anvil – if they try hard enough.

    I’ve got a couple of (former) MAG Tactical lower receivers built and have attached upper halves ranging from 22LR to 5.56 x45, .300 Blackout and 7.62 x39.

    Thousands of rounds “processed”. No. Problems.

  • Kenneth Allen Donaldson

    He may have cracked it unknowingly and unrelated to shooting. Lots of stocks have been broken when someone falls down or runs over them. Never assume anything, that’s all.

  • Meyhem

    Doubles as a fire starter too!

  • Tom

    When heat builds up to a certain point, magnesium really gets “interesting!”

  • kb7rky

    Alloys are inherently bad. Too much risk of failure, as evidenced by this one.

    I’d rather have full milled steel, instead of an alloy.

  • 1inidaho

    Call me old fashioned but I think I will stick with the old reliable, extra weight and all.

  • ToddB

    Is an AR15 really that heavy? Maybe if people did not weigh them down with ‘accessories’.

  • Jenny Everywhere

    That metal looks sintered to me. I’m no metallurgist, though. That grainy appearance and uneven break pattern looks like it was compressed and heated powder moulded to shape, not billet metal machined to shape.

  • Aloysius Jenkins

    I have a Mag Tactical lower. It’s perfectly in spec, the rifle weighs just under 5# with an optic and an empty magazine, and I don’t run around playing commando and mortaring it on concrete every chance I get. Guess what, it’s not broken. Add 9# of glass and lights and lasers and grips and ACRONYM levers to a 7075 receiver and you can break one of those too, pretty much in that exact (and known weak) spot.

    • Mr. Smith Wesson

      Da Nile isn’t just a river in Egypt.

  • Al Shartpants

    Fostech bought Mag Tactical so hopefully they put some serious thought and engineering into the product.

  • Donald Darr

    I’d rather have the weight if that means reliability.

  • Billy Vegas

    I had a Bushmaster Carbon 15 do that to me

  • Donald Darr

    What ever happened to the titanium lower I remember hearing about years ago? Lighter than aluminum but stronger than steel.

  • lowell houser

    Goodnight. If you CAST a lower with a home foundry setup it probably wouldn’t fail that badly.