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)

  • arorak

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    Brian Keating, to suggest that an AR is technologically superior to an AK is tripe. AK is simpler in design and malfunctions less in heat and cold. Less accurate over 300 but just as deadly. Older doesn’t mean technologically inferior. Now as far as polymer lowers go they are great and can be made at home on a 3d printer. Just look at the Steyr AUG used by the Austrian military, tested in heat and battle. The entire receiver is polymer and not one reported issue. Think the problem is with individual manufacturers rather than with the polymers.

    Reply

  • nagzul

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    I bought a FMK polymer lower with DD upper. After going to the range for the first time I found the lower cracked on both sides of the buffer tube when I got home, it was barely still connected. LGS is sending it back and FMK promises a fast turn around. If there were any aluminum lowers available id buy one. But since these are all that are available, ill stay with it. I am torn. I’m gratefull the lifetime warranty is bullet proof and they are going to replace quickly. (I just hope they are around a good number of years) on the other hand first day failure sucks… BAD. Luckily I bought an AK as well. If SHTF ill be grabbing that.

    Reply

  • DB Cooper

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    Josh,
    Just one more thought. Maybe its the balance of your AR and not the weight. With a lighter lower the weapon is now barrel heavy. Changes in centers of gravity and be perceived as a weight issue because of the way you have to support the weight. Just pick up a 10lb dumbbell then a 10lb bag of potato’s by the top of the bag only.

    Reply

  • Josh

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    Thanks everybody for your input, just seems heavy I think a lot has to do with barrel… Maybe I was use to shooting the M-16 A2 A4 the M4 while I was in the service I don’t know… If it has to do with me not picking one up in a while or what.. Put thanks again for your input

    Reply

  • DB Cooper

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    Josh,
    Don’t forget even lightening your rifle has trade offs. In traditional rifles, the lighter the rifle the more vicious the recoil. You can lower the recoil by going to a lighter bullet (another trade off).

    With the AR platform, recoil isnt a problem so you have to ask yourself am I going to be using this for close up or longer range shooting. The lighter the rifle the more your body movements will affect your accuracy at longer ranges. Personally (not knowing you of course), I’d say you might be wiser to start going to the gym and building some arm strength. Not trying to be a smart alleck but even your average tricked out AR rifle just isnt that heavy. My opinion of course.

    Reply

  • Jay Sprouse

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    Josh, in response to your question, I guess it could be a number of things, but if your AR has a fairly common forged flat-top upper receiver, then I would look first at the type of barrel you have. If it is a heavy contour barrel, then that will add some weight. Next consider the type of forearm you have, alum. quadrail types can be a little heavier than poly types like glacier guards or Magpul MOE types.

    About the gas tube. If you have an A2 style front sight, then, yes it probably acts as your gas block as well. You will need to change the gas block to a low profile type or a gas block with a rail on the top to use a flip-up type sight.

    Reply

  • Mosin Guy

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    Not being an expert on the AR but have several of my own I can say the front sight post that comes on many ARs has the gas block incorporated in it. You can remove the front sight block and slide it off the barrel then simply replace it with a railed gas block of the same diameter to which you can attach a front sight of your choosing. There are many available, some with no rail up to those with quad picatinny rails for attaching all kinds of peripherals i.e. lights, laser sights, bayonet, etc. As far as making the upper lighter it is not so easy. Until carbon fiber gets to be more commonly used in the barrel and receiver there is not much you can do. You can lighten the fore end by the one you may choose and the butt stocks come in many different styles that give you choices in terms of weight. The polymer lower; however, is a great improvement in terms of weight and durability. There are probably other readers who have much more experience with your issue who can be more helpful.

    Reply

  • David Weller

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    Sure, Josh.
    1) Everything is a tradeoff. Most handguards are heavier than needed for normal use. If you want to spend the extra $, and don’t want to hang a bunch of ninja crap off it, look into a carbon fiber handguard.
    2) Barrels and flash hiders can also contribute. If you want light, get an M4 carbine profile or “pencil” profile barrel (most AR-15s these days have m4 profile barrels, so there’s probably not much weight savings you can make).
    3) There are companies, like Yankee Hill, that make gas blocks that incorporate a flip up front sight. They’re handy and not heavy at all.

    If you do these things, combined with a lightweight polymer lower, you can easily have yourself a 6lb rifle!

    Reply

  • Josh

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    I have a question maybe someone could help me.. Today I bought AR 15 it has a lower polymer receiver. I don’t know who makes the upper but its heavy to me I was wondering why is that.. The AR I looked at that cost 2,000 dollars that would have cost like 900 dollars before all this about banning them was lighter as hole… Is there anything I can do to the upper to make it lighter? Then my final question can does the gas tube connect to the front sight post? I would like to take that off put folding sights on.. If anybody could help me I would appreciate it..

    Reply

  • Peter

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    Aluminum or Polymer, if the component parts are put together correctly, it will work. The contrary is true. The strip lower does not move, it is box to put in the components. Northern Frontier’s pin at the buffer tube is poorly build, the aluminum’s design is the same but may be better build. I had the NF’s pin at the buffer tube came out, but this can be fix. The pin at the buffer tube can be design with screw thread type and you will never have the pin problem. Manufactures need to look at this and this is the free idea design I just give.

    Reply

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