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Old January 17, 2012, 10:33 AM   #1
oo0juice0oo
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Polymer Lower Receivers

Got into a discussion with a buddy the other day about using polymer lower receivers on an AR15. He ordered one so I guess I can really make my judgements then but I wanted to see what you fine folks thought of them and if anybody had any experience with them. I found a deal on slickguns.com on Plum Crazy complete polymer lowers for $114 shipped, and it's a little tempting. I told my buddy that having a polymer lower on an AR just doesn't seem right to me, seems like there would be some kind of wearing from the internals or something. He says that they are supposedly 80% lighter and 50% stronger than traditional metal lowers. He also points out that I don't complain about the polymer frame on my Glock. Thoughts?
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Old January 17, 2012, 10:48 AM   #2
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There's very few companies using polymer receivers on ARs. They don't save a great deal of weight, they aren't any cheaper, and they just don't seem to stand up to the same kind of use.

For $114 shipped, I'd sooner get a SAA lower from AIM Surplus and have plenty left over for the stock of my choice (IIRC, Plum Crazy had the molded in A2-style stock... I could be wrong though). If somebody really wants to build up the lightest possible AR, then sure, they can probably shave a few ounces by going that route, but you'd need to match it to a lightweight profile barrel and choose all other components for weight if you want it to amount to anything. Mate it to an el cheapo HBAR (the heavier profile barrels require less machining so they tend to be less expensive), and you just spent all that weight savings and then some.
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Old January 17, 2012, 10:51 AM   #3
tirod
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FN SCAR, Remington ACR, ad infinitum. Stoner used the barrel extension to lock up the bolt, all the lower does is hold the parts together and be strong enough to hoist a fully loaded soldier into a window, or get the stock slammed into the ground on a three second rush.

It does not take steel or even forged aluminum to do that. The M14 does it with carefully selected cheap white walnut stained brown. Most wood stocks can be broken at the wrist, plenty die of unnatural causes being flung off the shoulders of high schoolers in ROTC. I've seen O3's, Garands, M14's, and M1 Carbines bite the dust. The FN SCAR has no anecdotal stories of breaking off the stock that I've ever heard.

The only parts that move in an AR lower are the little ones, and aluminum isn't self lubricating at all. Hasn't been any problem there.

For the price point, as soon as someone gets enough strength in the buffer tube shoulder to screw one in and not break the lower under real world stress, they will own the AR lower market. At half the price with parts included, it's simply a matter of time.
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Old January 17, 2012, 11:21 AM   #4
Jim243
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Quote:
There's very few companies using polymer receivers on ARs.
That is true. But to polymer or not to polymer that is the question, is it far better to get a metal gun or one with parts made out of plastic, is it better to wear nylon socks or ones made with wool, should I get a car made of steel or one that has a lot of parts made of carbon fiber???

Is a 7.2 lb AR better than a 5.6 lb AR??

I believe the expression is "wake up and smell the coffee." If you are going to have an attitude about something different then you should have been there in the 1960's when Eugene Stoner came out with the idea of using aluminum and plastic parts for a new rifle called an AR-15/16.

Maybe Glock should have used wood instead of plastic for the frame of his G-17. Maybe you should have been there when Henry Ford said the horseless carriage would replace Old Bettsy.

Give me a break, they are 50% lighter and 80% stronger than aluminum.

Will they wear, only time will tell. But it sure looks like it.
Jim

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Old January 17, 2012, 12:17 PM   #5
Technosavant
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Quote:
Is a 7.2 lb AR better than a 5.6 lb AR??

I believe the expression is "wake up and smell the coffee."
I had a large response here, but you know what? If you're so invested in this that it's got you this worked up, it ain't worth it.

Last edited by Technosavant; January 17, 2012 at 12:25 PM. Reason: Why bother?
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Old January 17, 2012, 01:05 PM   #6
Jim243
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I felt the same way about polymer frame pistols. Matter of fact purchased my first AR in 1967, a Armilite AR-15 20 inch rifle with plastic handguard and butt stock. Sold it 20 years later and never a problem with the aluminum frame or plastic parts. First family telephone was in 1948 a bakelite brick black (only color they made) now my iPhone never leaves my pocket.

If I knew what would come out next, I'd be a millionaire, but I'm not.

I thought Tasers were a funny thing, now every cop on the beat carries one.

Who knew.
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Old January 17, 2012, 01:57 PM   #7
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It has nothing to do with polymer itself (heck, the one polymer gun I have is a plastic revolver... if that won't hark off the purists, NOTHING will). It's more the implementation- I just don't know (to my own satisfaction) that the quality of the polymer lowers is there. Since the price is not much of a differentiating factor and neither is weight, I just don't really bother, and the result is I tend to not recommend them either.

I'm hardly a Luddite- I've just seen mixed reviews of the things.
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Old January 17, 2012, 07:43 PM   #8
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I think you're missing the difference between polymer and carbon fiber construction. The PC lowers are carbon fiber which is stronger and more stable than typical polymers.
I have no doubts about the strength of the lower and NO the stock is not molded on. It uses the same threaded connection as the standard aluminum lower.
The newer PC complete lowers use synthetic fire control parts which I DO have concerns about although none I know of have failed. I've owned, assembled, and/or shot a total of 7 of the PC lowers so I do have some hands on experience with them.
I don't care for the balance when the ultralight lower is combined with a 20" or heavy weight barrel. Way too muzzle heavy.
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Old January 17, 2012, 09:45 PM   #9
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I have an ar built on a plum crazy lower. I like it. almost 1000 rounds down range, no visible wear. The rifle is lighter than my other ar's. The trigger is substantially better than any G.I. trigger I have used. When I built it, it cost me about 80 bucks less than it would have cost me to build one on an aluminum lower. I say go for it
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