Polymer Lowers

>>33596530
some are. some have reinforcement (brass, steel, aluminum, et c); some have a stock molded into them (plum crazy did that for a while).

basically, don't beat on doors with them or really pull hard on the grip/stock into your shoulder. you flex it a little and the action breaks it apart at the web.

>>33596530
My friend had a all poly AR that shit the bed in like 3 mags (he bought it second hand though). The BCG got out of it's rails and warped the upper out of spec.

I was curious about butt-stroking someone with one of these stocks. Can you break the jaw bone without it breaking in a CQC situation?

>>33596530
Pic related is namely polymer lowers that are the exact same dimensions as regular aluminum lowers, the problem being aluminum is vastly different than polymer(duh) and You end up with weak points.
There are reinforced poly lowers or even enhanced dimensionally ones where that buffer area is beefed up.

Plastic garbage.

>>33596530
ARs aren't heavy to begin with. Just use a normal lower, make your rifle less durable for the sake of saving a tiny bit of weight. Seems stupid to me.

>>33596530
>Are they still prone to failure like pic related or has that been sorted out?

Poly AR lowers are garbage. The AR was designed around a forged aluminum lower, it should stay that way. The buffer end of the receiver is just too fiddly to be effectively made out of plastic, even with some of the reinforced poly lowers, since you are limited on the wall thickness by clearance for the charging handle.

Just be a reasonable human and get an aluminum lower. You can buy a cheap forged aluminum lower and have nearly the same results (or better, sometimes) as an expensive billet lower. If you buy a cheap poly lower, you are a fool parted from your money, and you wasted your time filling out a 4473 for scrap material. The lower is the actual firearm- it ought to outlast every other part on the gun by a significant margin.

>>33596585
>have an out of battery
>blows up
>polymer lowers, amirite?

I wonder how carbon fiber receivers hold up

>>33596530
TN arms is the only one that's not shit

>>33596530
The ones that are like the dimensions of Aluminium lowers are shit. The ones designed from the ground up with polymer in mind are usually not too bad.

>>33596530

I picked up a Plum Crazy Lower a few years back and slapped a discount DPMS Oracle upper on it.

It really ran fine, and it's low weight/cost was pretty cool, but after so many photos like OP's, I just gave it away and picked up a 2nd hand DPMS lower.

I had no issues, but after the umpteenth pic of broken lowers, I just couldn't shoot it without worrying about it exploding in my face.

>>33597259
the OP pic wouldn't' explode, it would just crack
If you didn't sell it, you got shafted
Worst case scenario you got more mileage out of it until it broke, then got a new one

>>33596846

Poorly. Carbon fiber is good for constant, smooth loading. It's shit for shock loading.

>>33596563
>can you break the jaw bone without it breaking in a CQC situation
>break the jawbone without it breaking

>>33597151
Can confirm. Mine is a 308 though.

am I the only one who wants a steel receiver AR ?

but can't because nearly nobody makes em
and those who do aren't available in europe

>>33597268

I hear that, but once I have lost faith in something, and start to worry about some sort of catastrophic failure, I just had to walk away.

For what it's worth, I gave it to a gunsmith buddy who used it for a lightweight build, and to use as a test lower when he was working on people's AR's. He has given me way more than the $100 cost in gunsmithing since then.

>>33597460
http://www.theflatspot.net/ar-15-receiver-flat.html

>>33596530
>detachable stock
That's a feature

>>33597445
Those aren't my correct pronouns, cis scum

>>33596530
They explode every time someone says redpill, it's the kill phrase for magpul garbage.

ARs are designed for an aluminum receiver, they're not Glocks
the ONLY reason to go polymer for a lower is if you're doing an 80% since polymer is a heck of a lot easier to mill/dremel than fucking aluminum
I have two poly ghost lowers, but they were just a fun project, not my choice for range/beater/fightin rifles

>>33597560
i know, but they are sold out and last time they were in stock they wouldn't ship directly to europe


what i meant was a factory forged/milled receiver, upper and lower if possible

>>33596585
>polymer lower
>shotgun cuck stock
LMAO underrated post

Tried some dude's .300BLK poly lower AR around a year ago and remembered the safety being really "plasticy" instead of smoothly rotating.

>>33596598
This. While people may have thought the same thing with polymer handguns, I have no idea why you would want a polymer lower AR when a regular aluminum one works perfectly fine.

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>>33596585
>>33596830
>>33598634
It's a kel tec su-16, not quite an AR

>>33596530
The CAV15 holds up quite well but it only has a fixed A2 length.

>>33598860
It's basically nothing at all like an AR; piston, entire body is flimsy plastic, no buffer, I'm pretty sure it only has two locking lugs even.

It takes NATO mags and is in 5.56, that's it.

>2017
>not using wood for your lower receivers

https://www.youtube.com/watch?v=L0CNVuyC5S0
http://www.weaponeer.net/forum/forum_posts.asp?TID=8035&PN=1&TPN=1

>>33598626
You want a turnbull. Check out that case hardening.
http://www.turnbullmfg.com/gun/turnbull-tar-15-rifle/

>>33596563
>butt-stroking someone with one of these stocks
where i come from that's called rape

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happened to me. ATI omni poly lower, 2013. came apart at the takedown pin hole on the second magazine.

The hole for the buffer retention pin was slightly undersize, causing the pin to bind and not retract to let the bolt carrier ride over it. The bolt carrier impacted the pin and the stress was transmitted to the lower.

There's basically no reason to do a poly lower when aluminum ones are the same or slightly higher price.

>>33601881
This. Don't waste your money OP.

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ITT: Nobody acknowledges one of the few polymer lowers actually worth someone's time.

>>33602020
I love the look of this lower. Really would like a lightweight ar build with it.

>>33602047
They are legit sturdy and don't shit the bed even from some fair bit of abuse, BUT, it will leave your rifle front heavy, so I suggest a pencil barrel to go.

Also, they are only in A2 length, so if you want it shorter like in the picture, it must be modified.

>>33602116
I already love pencil barrels.

Length is less of a concern for me than weight.

>>33602020
>one of the few polymer lowers
more like the only.

>>33602139
I'm thinking if you could get a 14.5" pencil barrel with a pinned hider, along with the proper length gas system and plastic handguards, you could balance it a lot better with the CAV15 lower.

Maybe get a flattop upper with no forward assist, shave off another ounce.

But I think also the CAV15 would be very well suited for a .22 build

>>33602351
What about for a strange 9mm build?

>>33602358
Could be done, but mind to pick the right buffer.

>>33596530
>Are they still prone to failure
Engineering 101:
Yes, if the designer has ignored material science. No, if he hasn't. If you design a polymer lower by taking the material properties into account, the lower won't have structural issues.
https://www.full30.com/video/31a73f8fade48648de9f917af92fdd53

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My lower is 3d printed. (100% infill, so it's still solid plastic, didnt feel like it needed to be lighter)

It's all designed to be printed flat, (z is the weak direction for printed parts) and bolt together.

The buffer threads and rear takedown pin are the high stress parts, wheras the upper maintains rigidity of the rest.

The buffer is literally 2 fuckin' inches wide and also extended for strength.

TL:DR, a plastic ar15 is just as strong as an aluminium (some are stronger) if designed for it. If you tried to make the buffer the same size as the aluminium one, it would fucking break if you dropped it.

>>33604685
what is that bayonet. please post more pics of your AR

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>>33605343

It's an M7 with some handguards I made.

Bonus, triangles.

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>>33602351
>I'm thinking if you could get a 14.5" pencil barrel with a pinned hider, along with the proper length gas system and plastic handguards, you could balance it a lot better with the CAV15 lower.
>Maybe get a flattop upper with no forward assist, shave off another ounce.

Like this?

The balance point is right under the front pivot pin, and as shown it weighs 5.5 lb *with* optic, sling, and loaded 20rd USGI mag. It's my wife's.

>>33596530
My poly lower crack at the front takedown pin

>>33596530
It's been reinforced. The bridge between the buffer tower and lower is the only real stress point. Thicken that part and you're golden.

>>33604685
No shit?
That's the vanguard lower, how reliably does she run?
Ive made a Phobos reviever from petg and its finicky with feeding.
I personally hate abs, it smells like shit.

I built an AR with a 80% polymer lower. Works just fine so far

>>33602047

this is what i did

>BCM 14.5 pencil barrel with pinned battlecomp
>aimpoint t1
>surefire scout

a bit over 7 pounds with a loaded 20 round pmag

>>33596530
>polymer
Never go with polymer lowers on a high powered rifles. Waste of money and very unreliable