Is the Polymer Lower a Good Idea?

By CTD Rob published on in Firearms, Reviews

In this industry, everyone wants to buy the highest quality products. However, in reality most people simply buy what they can afford. Our biggest sellers are not $1,200 ARs decked out with the latest gadgets. By a huge margin, our top sellers are the least expensive guns we can ship out. This is a simple fact of capitalism. Most major gun manufacturers tweak its assembly processes to reduce cost, thereby increasing profits. More plastic means less money required for investing in materials. You might notice that it is becoming more difficult to find a modern duty pistol that isn’t made of 50 percent polymer.

ATI Omni

ATI Omni

The AR platform is no exception. Traditionally, much of the AR is already plastic. However, recent developments are pushing the limits of AR design, and the polymer lower receiver is now commonplace. Many shooters will scoff at a polymer lower, but I think it shows some degree of promise. New Frontier Armory produced some torture test videos to show its plastic product, the LW-15, isn’t a junky ill-fitting gun part. Additionally, American Tactical Imports produces its Omni lower which has realized good deal of success on the market, despite a few wavering reviews on its ability to pair with mil-spec uppers. Since only a handful of owners reported problems, you can probably assume there was an out-of-spec run that made it past quality control.

The biggest question people have with polymer AR lowers isn’t usually the fit of the product, it’s the durability. In the 1980s, Glock faced significant market resistance due to the perception that plastic guns could never work. Today, Glock is the most popular choice by police departments around the world. The early versions of M16s had plenty of detractors both inside and outside of the Army’s weapons program. Much of this stemmed from the partial plastic construction. High-ranking brass were accustomed to large, heavy, .30-caliber wood and steel rifles that felt more substantial.

ATI HD16

ATI HD16

When you study the AR lower closely, you’ll notice the only part of the component that could face any real stress is where the buffer tube screws in to the receiver. If a polymer lower was going to fail, it would be there. While the recoil of a .223/5.56 NATO is minimal, that part of the lower still bears a significant physical load. Part of the reason polymer pistols work so well, is the lack of a buttstock component. Imagine a Glock pistol with a metal tube screwed into the back of the grip, which feeds into a buttstock. Much of the recoil force would cause stress on the point where the two components meet. That part of the AR lower has a similar role and there have already been a few broken polymer lowers floating around the Internet. Since we weren’t there to witness how they actually failed, we won’t know if this was caused by normal use, or by someone mounting a .50 BMG upper on a polymer lower and whining about it breaking.

My polymer lower comes in next week. If it breaks, then I’m out a little over $35. However, I really don’t think that is going to happen. We aren’t going to throw it around and run over it with a truck. The job of this rifle will simply be to shoot .223 downrange, and that’s all I expect out of it. While I wouldn’t consider using a polymer lower AR as my SHTF gun, I think the low cost and reduced weight make it a viable option for training or for a first-time owner. We’re going to see a lot more polymer lowers in the future, hopefully they’re up to the task—time will tell.

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Comments (120)

  • Deebow

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    ALL: A few things to keep in mind…

    Those that worry that the rifle will break if you buttstroke someone with it: Aluminum bends and breaks too. In my 25 years in combat arms I butt stroked exactly 1 person, didn’t break the rifle.

    Rifles are for shooting, not clubbing. If you are using it for clubbing, you didn’t bring enough bullets.

    If you connect this polymer lower to a COBB .50 upper to make your hybrid super rifle complete and expect it to work, you might not be smart enough to own a gun.

    If you have to “mortar” a rifle to unjam it, you are doing it wrong and if you do it hard enough, the buffer tube could be made of concrete and still break, rendering your rifle useless.

    I am certain that the polymer upper I have just purchased, when connected to a decent upper receiver will work just fine to ward off home invaders, coyotes, and the occasional zombie.

    I will post more after torturing it with some range time and let everyone know what I found out.

    Reply

  • James E. Barnes

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    I have owned a GIN_U_WINE Colt AR-15, which i put thousands of rounds thru before I traded it off. I then bought a cheap copy from a company that now sells thousands of them…it was crap, jammed every 2-3 rounds, and i traded it off.
    I have owned a few Glock sidearms, which have always served without fail.
    I recently purchased a New Frontier Arms complete lower, made in polymer. I took it down to test fire, expecting about the same results as the other cheap nock-off…
    boy was I surprised. It fired without fail, recoil was almost non-existant, and was just a pleasant little firearm to shoot.
    Admittedly, I’m still in the testing phase for this weapon. It will have to prove itself, but I am very happy so far. I am a little apprehensive about the internals being poly. I was expecting metal. Seems to me like the hammer would wear out faster, i’ll have to see over time. I really like the feel of it tho.
    I don’t really like the stock that’s on it. It locks, but rattles around. If you twist it a quarter turn it doesnt rattle, but it’s still annoying.
    I like this little weapon, and as a truck-gun, closet gun, it should be great.
    As a tactical weapon, i’ll let you know after i get thru running these 1500 rounds thru it.

    Reply

  • Brian Keating

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    What is the aversion to better technology? If you are using an AR-15 instead of a M-1 or M-14 or AK-47, that more or less places you in the “technology is better” camp. If you don’t like polymer or aluminum, just stick with the old wood and steel weapons. I like technology and apparently Eugene Stoner did, too. If polymer lower receivers are equivalent in durability to forged aluminum lower receivers then the concept and execution is precisely in line with Stoner’s ideas about how to equip our military with the best small arms available in terms of cost, weight, and durability. My only suggestion is hardened steel or aluminum inserts for the pins and buffer tube. Glock does it and NFA can, too. Polymer magazines are already clearly superior to aluminum magazines and this is just the next logical step.

    Reply

  • David Weller

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    Wait, that can’t be right. Somebody said they were wrong on the internet. This surely portends the end of the world is coming! :)

    Reply

  • Jay Sprouse

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    I stand corrected!! You are right David. You will notice that I said “owned”, I sold the NF lower about 3 months ago and now I only have the Plumcrazy. Before tonight I would have sworn that the NF was marked 5.56, but I just visited their website and their lowers ARE marked multi. So, I was wrong. :)

    Reply

  • David Weller

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    Jay said, “all have clearly stated “for use with the 5.56/223 caliber only!! They are not multi-caliber lowers.”

    Really, Jay? Because New Frontier Armory lowers don’t say that. They’ve been used extensively in multiple calibers. I use one for my 6.5 Grendel, no problems. They are designed for multi caliber use.

    Reply

  • Jay Sprouse

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    Jaybird, I am not sure what brand polymer lower you bought, but I have owned both the Plumcrazy and the New Frontier brands, and all have clearly stated “for use with the 5.56/223 caliber only!! They are not multi-caliber lowers.

    Reply

  • JayBird

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    I bought one of these polymer lower, put my AAC 300blackout on it. Reciever extension stripped just like the above comments. Held up for about 100rds. Sent it back. Supposed to get my new one Tuesday. Hope it works better.

    Reply

  • Glen2Gs

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    I’m surprised to see that no one has mentioned the DIY AR15 lower project….all you need is the software and a 3D printer

    http://defensedistributed.com/

    Reply

  • Frank

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    “Carbon fiber and aluminum are BOTH stronger than steel by wieght and not by volume” Maybe – but we are used to comparing things like firearms parts automobile frames and stuff we are all familiar with. The bottom line is: Two parts of identical shape and size, one of which is steel and the other is aluminum – the steel part will be stronger given the strongest alloys were used in both. Carbon fiber parts will be stronger than steel but are a little different. This is a quote from a website that makes carbon fiber parts for building construction: (begin quote)

    Carbon Fiber vs. Metals
    When designing composite parts, one cannot simply compare properties of carbon fiber versus steel, aluminum, or plastic, since these materials are in general homogeneous (properties are the same at all points in the part), and have isotropic properties throughout (properties are the same along all axes). By comparison, in a carbon fiber part the strength resides along the axis of the fibers, and thus fiber properties and orientation greatly impact mechanical properties. Carbon fiber parts are in general neither homogeneous nor isotropic.
    The properties of a carbon fiber part are close to that of steel and the weight is close to that of plastic. Thus the strength to weight ratio (as well as stiffness to weight ratio) of a carbon fiber part is much higher than either steel or plastic. The specific details depend on the matter of construction of the part and the application. For instance, a foam-core sandwich has extremely high strength to weight ratio in bending, but not necessarily in compression or crush. In addition, the loading and boundary conditions for any components are unique to the structure within which they reside. (end of quote)

    So – its not just the material but how it is molded and the direction of the fibers. We could also add Kevlar to the list of things we call “polymers”. I think the M16 /AR15 have become heavy to the point that the original intent of the weapon has been all but lost. That was a light, balanced, easy to shoot and carry light infantry weapon. Making the uppers and lowers out of some “polymer” will not increase the effectivness of the rifle. In fact, taking weight off the lower and upper makes it way less accurate. Added weight absorbs some of the recoil and that improves accuracy. The rifle will also be front heavy and not balanced any longer (not that the A2’s 3s and 4s are balanced any more anyway) The only M16s that were balanced were the A1s with the pencil barrel. Give us a stainless rifle with a pencil barrel and we will love it! I guarantee!

    Reply

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