How come polymer ARs are shit, but polymer handguns are okay?

>>34221511
Rifle rounds are far more powerful than pistol rounds. Read a book ffs.

>>34221511
They aren't. Metal frames are far superior

>>34221511
Elitism, and the fact that they could potentially blow themselves apart.

When an AR is a lego kit, you don't cheap out on the most basic parts.

>>34221511
>that bowed dustcover

How old are you, did it make you feel good to make a big boy thread on /k/? Do you think you are worth something now?

No, you are under 18 and will be for some time but you still think your opinion or even thoughts are worth anything.

How did the magazine break?

>>34221632
the gun exploded. magazines are typically in the gun, in very close proximity to the chamber.

>>34221632
Probably a double charged reload, as alluded to earlier

The bcg is split, that failure had nothing to do with the lower.

>>34221511
the best aluminum alloy or the shittiest plastic. This would have happened.
>>34221611
>>34221697
Its been stated

Neither are bad, you fucking retard,

>>34221511
Neither is okay. the PLASTIC ar lowers are typically lower quality and larger with more flat unsupported areas. where as PLASTIC pistols tent to be bulky so it only explodes through your hand.

>>34221511
ARs weren't designed to be polymer.

>>34221511

Because OP, when you take an AR part that's supposed to be aluminum, and then keep the geometry for that part but just switch material, shit gets fucktarded. This is why CavArms lowers withstand shit and "I took der lower and just made it plastic" fucktard specials snap at the rear retaining pin.

Pistol frames designed for plastic from the ground up are a similar case.

>>34221549
>They aren't. Metal frames are far superior

Retard.

This is now an AR blowing up thread.

https://www.youtube.com/watch?v=Oh1lyMyejpI

Dude why do you post a pic where the polymer lower clearly isn't at fault? I mean look at it the bcg is wrecked and the upper is bent to shit.

>>34223694
Was that a squid or what? I mean the bolt wasn't going into battery and hence he was smashing the f/a so i guess the bolt wasn't locking correctly but idk how the firing pin managed to hit the primer if it wasn't in battery.

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91KB, 1920x1080px

>>34221511
Plastic lowered ARs aren't actually shit, they just suffer from poor design with the material at hand. There is a weak point at just under the buffer tower. What you do is integrate a permanent grip and increase the material under the buffer tower.
Problem solved. Look at warfairy's designs, specifically the charon, you'll see what I mean.

The explosion in OP's pic had nothing to do with the lower, it was an overpressured cartridge.

>>34224513
ATF is trying to scare people away from unregistered home builds.

>>34221552
you do realize that all those forged lowers come from the same fucking foundry, right?

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>>34221511
Most polymer lowers are just castings or copies of aluminum lowers, which doesn't work because it's not a shape that brings out the potential for strength in polymers. The typical AR15 lower shape is just not good for plastic.

The CAV15 has it's grip and stock monolithic with the lower, and thus it holds together well, the curve/arch like form of the grip leading to the stock is strong, the entire lower supports itself, rather than on say, a Carbon15, where the buffer tube area always snaps off in a few hundred rounds.

The CAV15 can be used to smash windows, teeth, noses, etc, and it will hold up, not to talk about not wearing out from a couple of cans of ammo.

It's not that they're entirely shit, it's that why would you bother when you can get aluminum forged lowers for like $50 now? There's also like one properly made polymer lower, from Cav Arms, and it's been beefed up and forces you to use a fixed A2-length stock. What do you gain, exactly?

>>34225224
A pound of weight reduction?

>>34225475
>a pound
That's a funny way of saying 5oz, but okay...

>>34224946
That doesn't mean they are all finished to the same tolerances. The machining process is what really determines the quality of a lower and upper.

>>34225522
Cav 15 weighs 1 pound 12 oz
Standard ar lower with m4 stock weighs 2 pounds 10.5 oz

>>34225841
A regular M4 profile lower will clock in a hair over 2 lbs...
http://www.m4carbine.net/showthread.php?25966-Weight-of-lower-receiver-assemblies

This is hardly a pound in weight difference.

>>34225923
It's close enough to a pound to be worth it for lightweight builds.

>>34223641
Yeah but what about polymer

>>34221511
I'll assume you are asking a serious question. The reason that polymer pistol frame work and polymer ar lowers fail regularly is that the pistol frames were designed to be polymer from the start while the ar lowers are made by taking an aluminum design and simply making it out of glass filled nylon. The reason for this is two fold, one is that it is easy since no redesign is done and the second is that it ensures that standard AR parts are compatible. The problem is that the material properties of the nylon are not comparable to aluminum and the idiots who make these either didn't consider that or chose to ignore it. Yes, the aluminum lower probably is probably overbuilt in some areas, but it isn't so overbuilt that you just do a 1:1 swap for nylon.

A decent lower could be made, but it would require engineering work and likely involve some dimensional changes to pad up some regions and metallic inserts all of which increases cost and makes it difficult to compete with aluminum lowers.

>>34221511
What's polymer?

>>34224946
try like 7 different foundries and 10-15 different machine shops.

>>34227829
Aren't the terms more or less exchangeable in common speech?

>>34228208
yes

>>34223686
took this long for the proper answer

rest of the thread go kys

>>34225076
Can you order one of those without an ffl?

>>34228425
No, they are only available as stripped or complete lowers.

>>34221511
Because all of those polymer handguns were designed from the ground up with the idea of having polymer in them. The only good poly AR lower out there is the Cav-15 and it's because it was designed as a polymer lower from the ground up and not just plastic poured into a normal ar lower molding.

>>34227922
Probably more machine shops than that, dude. I toured a little machine/ tooling shop building lowers for rock island in BFE, Michigan. They outsource all over the place.

>>34227922
Try about 20 forges and any one with a CNC machine/Type 7 FFL and up.

>>34223675
This.
As Karl and Ian have said before a polymer lower made to the same dimensions/tooling as an aluminum lower will fail. You can have a good polymer rifle but the design has to factor in the material properties. (i.e. it has to be thicker in the load bearing areas)

>>34224919
Speaking of which, could I do an aluminum lower with a drill press and a jig or is a milling station required? I've seen people do functional polymer lowers with just a dremel, but idk.