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Polymer lower question

2K views 17 replies 7 participants last post by  soundguy 
#1 · (Edited)
Guys, I have never owned an AR but I am determined to make sure I have one even if I have to build it myself from scratch.

I need your input regarding polymer lowers. When I get a lower receiver I have the only part that needs the FFL transfer. I may get an ATI polymer lower for 50$, 10$ shipping in the next couple days (If I'm lucky). I can buy it outright for 75$.

All you AR guys, please, I'd like your input on polymer lowers. I do have my own reservations about them yet I do see some advantages to polymers. For basic plastics the half life of decay is 500 years. Polymer plastics may very well be stronger and lighter than metals plus they do not corrode.

Space shuttle tiles were made from ceramics.. yes, other materials than metal do have their special properties.

All you AR guys, what do you think? Have any of you ever seen a polymer lower fail?

Thanks in advance,
Will
 
#2 ·
Check the thread you started about panic buying. jjmitchell posted about them there after I commented that I would buy one for $60 just to see how they perform against forged aluminum lowers.
 
#3 ·
Will i'd stay away from a plastic lower, even if I was building a .22 and defenatly wouldn't build one for center fire. Save your change, you'll be happier in the end buying a metal lower.
 
#4 · (Edited)
The problem is simple with them.

A gun designed to be made of a certain material, say forged aluminum. It is designed for the strength of it. Now take that same design and change the material to plastic/polymer such as the case here. There are weak points in the end product that can and will break much easier. And that also happens to be the case with polymer lowers.

I would be very cautious of what you read on the internet as far as these lowers being a good thing. Many are from plain idiots that don't know better and some are from those related to or paid by the manufacturers of them.

I have seen too many failures to ever trust one even if they were free. And I'm sure someone will come along here and say how they have fired X amount of rounds with one. I don't care how many rounds you fire at a range setting at a bench, an AR is not a bench gun. Only after they are tested and approved for use by our military will you see me even think about buying one and I don't think that will ever happen. The material is just too weak for the design period.

Just use common sense....

To me anyway it's sort of like building an offroad truck to run the Baja and using a polymer frame to save a little money. It might drive around town just fine but when it comes time for it's intended purpose it won't finish the race.



This one is too large, click on the link below.
http://img213.imageshack.us/img213/2957/cavarmslower3.jpg





Some of the "just fine" polymer trigger parts;






There are plenty of picture like these if you look around. Forged aluminum lower pictures with failures are very rare.
 
#5 ·
A little super glue and that'll be good to go. :rolleyes::D
 
#6 ·
I bought a complete polymer lower right before the stupidity took over. I paid right at $115 for it (give or take $5). I bought it specifically to attach to a 5.7X28 upper. I know the 5.7 doesn't have the power that a 5.56 does but I have not had any type of problem with it. As it stands right now, I would not have any problem in buying another one. I am sure if I look hard and long enough, I can find pictures of AR lowers made of aluminum that are cracked or broken, too.

Next time I take my AR-15 to the range, I will swap lowers and put the plastic one on the 5.56 and see what happens with it. There have been polymer handguns for a few years now and there doesn't seem to be any major problems with them.
 
#7 ·
I bought a complete polymer lower right before the stupidity took over. I paid right at $115 for it (give or take $5). I bought it specifically to attach to a 5.7X28 upper. I know the 5.7 doesn't have the power that a 5.56 does but I have not had any type of problem with it. As it stands right now, I would not have any problem in buying another one. I am sure if I look hard and long enough, I can find pictures of AR lowers made of aluminum that are cracked or broken, too.

Next time I take my AR-15 to the range, I will swap lowers and put the plastic one on the 5.56 and see what happens with it. There have been polymer handguns for a few years now and there doesn't seem to be any major problems with them.
If you can find them with the same failures please do so as I would like to see them too.

And it doesn't have to do with "power" of the round or how many shots you fire, it's just not the correct material for the application. Look at the failures in the pictures, I don't see any caused by recoil.
 
#8 ·
George, its kinda like asking me if I would buy a poly 1911. The answer is NO. Not just because of the durability, but just because. I dont feel like a 1911 should be made of poly and neither should an AR. Thats just me.
 
#9 ·
i'll stir the pot wit this. :)

While I was a wanabee ar owner.. I bought a keltec su-16c it's kind agot the look of an ar.. fires 556.. etc.

I have fired the HECK out of it... no problems yet.. i got one as soon as they hit the store shelves. I have plenty of other kel tec gear.. p32, p3at, KSG etc. I like their quality.

for some reason I DO agree with Double D.. i would NOT want a 45acp poly gun. As for alumin framed guns? I have a sigp238 that I like better than my heavier larger p230. my mom has a charter arms ( their version of an air light ) 38 snub that she LOVES.. though she disliked my tarus 85 and smith steel framed 38 snubs.

i don't think I'd own any magnum chamberings in poly or aluminum though either. ;)
 
#10 ·
You need a bigger spoon Soundguy.:)

The Kel-Tec is "designed" for the materials it is made from, same with Glock and all the others that use a design to match the material.
 
#11 ·
You need a bigger spoon Soundguy.:)

The Kel-Tec is "designed" for the materials it is made from, same with Glock and all the others that use a design to match the material.
well.. that's my point.

if a keltec su16c can be poly and it's made for 556... why not an ar15?

heck.. there's more poly on the 16c than an ar with simply a poly lower :)

make sme wonder if some of the poly lower fialures were with some other chambering of upper than 556 ???

again.. just guessing / stirring the pot. ;)
 
#12 ·
I don't see recoil as the main reason for any of the failures showing up so far.

I believe you could build a 50BMG with poly as long as it was designed for it. But you can't just copy the parts made of metal and make them with poly and expect it to work.

I am not knocking poly or any plastics used in firearms today. They are good to go when used properly and as of yet I haven't seen one poly lower that I would trust.

Things most likely will improve, they are getting better...but they aren't there yet.

Will, I know how bad you want an AR, I really wish I could help you reach that goal. If I had a real lower I would send it to you. Money is real tight with me right now too. Save up a little more for the forged lower, you will be much happier in the end with a gun you can depend on for anything. Good luck.

.
 
#13 ·
Thanks guys, I certainly do have my reservations about polymers. I brought this topic up because of the plethora of pistols using them, all these Glocks even Rugers plus a host of others with polymer frames and even slides. My personal feeling is that I don't trust them - any of them. However, with the vast numbers being produced I felt I needed to take an honest 2nd look at the situation and determine if my feelings about the materials are just plain pig headedness.

Granted, I'm with Double D on the 1911 and I have a very strong sentimental attachment to that pistol. If anyone made a 1911 with anything other than quality steel I'd likely want to bang their head against a wall to knock some sense into them.

Chemically though I do know that compounds can be manufactured that are more durable, stronger, harder and lighter than steel. Carbon fiber is such an example as is pure carbon mono filament (which has to be manufactured in a complete vacuum and zero gravity). Sadly, the manufacturing costs of such materials is too high to make them a viable option for gun parts still. The same is true for ceramics.

GunHugger you hit the nail on the head with how much I want an AR, I want to make about 5 of them in different calibers. I'm thinking also of buying a number of 85% completed lowers and talking with the tactical local company who has a CNC machine to let me use time on it to program it and make my own completed lowers for my use. That is actually perfectly legal since they aren't for resale. There are a number of companies with the mostly completed lowers readily available to ship to my door that simply need the final milling done.

Again, thank you guys.
 
#14 ·
Soundguy, I did not say I wouldnt want a 45 in poly, I did say I wouldnt want a 1911 in poly.....I already own poly 45s......
 
#15 ·
I'm thinking also of buying a number of 85% completed lowers and talking with the tactical local company who has a CNC machine to let me use time on it to program it and make my own completed lowers for my use. That is actually perfectly legal since they aren't for resale. There are a number of companies with the mostly completed lowers readily available to ship to my door that simply need the final milling done.
Will, I know several guys that have done exactly this and my next one might be done this way as well.
 
#16 ·
If you can find them with the same failures please do so as I would like to see them too.
No I could not find any with the EXACT same cracks, but here are a couple metal ones with cracks in the Lowers and one with a cracked upper. One of these is a Bushmaster, the other one is a DPMS, and I don't remember what the upper is. I could probably take my Rock River lower and break it if I really tried, hell any AR could be broken if you beat it against things or used a castle nut wrench with too much pressure, or used it as a pry bar. With a little common sense, a polymer lower should last you just as long as a metal one. The question that comes to my mind, is what caused the cracks and breakages shown, just plain shooting them sure as hell didn't.

I wouldn't particularly buy a 1911 made out of plastic, but I am open to trying one out. This argument went on a few months ago when someone mentioned polymer lower.

If you are looking to win this discussion or argument, it just ain't gonna happen, we all have our own opinions.
 

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#17 · (Edited)
The first picture, I'll have to guess the damage was cause by someone turning the tapered threads of the buffer tube too far into the lower. It either stressed it and it split after firing or it cracked right away, don't know for sure. Or something else was out of spec. They don't usually do that even with much abuse.

The bottom one ??? looks like machining not a break, what happened?

I have a few pics of AR's completely blown up from ammo or some other malfunction. That doesn't mean they were weak. The failures I see in poly lowers isn't from recoil or ammo malfunctions, they just break at points not strong enough to be made the same as forged aluminum.

I won't ever understand why anyone would want a weaker gun just to save a few dollars. If $50 - $75 more for forged is too much then I will suggest another type of gun. AR's aren't cheap and they real easy to spend a lot more money on once you buy or build one.

I would never spend all at one time the amount of money I have in three and their related items. But a little here and there...well it isn't noticed as much. When I added it all up it surprised me. The thing is, a little more for a forged lower isn't a big deal.

I missed the last part of your post so edited to add;
WIN, you say? :D I didn't know we were even having an argument. But...if you buy a poly lower or own one now, I do win because my AR's are stronger than yours. That is a fact that you can not prove wrong. Now you tell me how you win. This is fun.
 
#18 ·
Soundguy, I did not say I wouldnt want a 45 in poly, I did say I wouldnt want a 1911 in poly.....I already own poly 45s......
when i typed that I was thinking hte same.. IE.. no 1911 45 in poly.

just wouldn't have the flavor of the original.

my buddy has a glock 30? in 45acp.. I just don't like it much ( nor any of the glock guns... another buddy has a 9mm ( not sure of model ).. it's a thumbnail eater due to the small sige of the gun and the way a 2 handed grip stance ends up on it....
 
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