Polymer AR Lowers

[raftman]

There's a handful of options out there for polymer lowers. Some of these manufacturers talk a pretty good game, even claiming that their plastic lowers are not only cheaper than aluminum but actually better, too. And the online reviews for some models like the Omega Arms E3 Gen 2 seem to be mostly very positive. Just wondering if anyone has had any of them long term and can speak to how well they hold up after thousands of rounds?

I bought one a little bit ago to play around with a 7.62x39 upper and have only about 140 rounds through it so far. The only issue so far is the hammer spring isn't strong enough to set off Tulammo primers some of the time (but seems to work fine with the other brands I've tried (Wolf, Brown Bear, etc). I ended up replacing it with a heavier spring which seems to have fixed the issue entirely. It's worth noting this issue is common to AR's when using x39 uppers, and not unique to polymer. The stock is a little chintzy and I may replace that as well. Guess only time will tell if this was a heck of a deal or a poor choice at any price.

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[Medic!]

If the upper is the serial numbered part like with a sig 556 or SCAR then I would try a polymer lower.
I'm not interested on doing a background check for a plastic rifle lower.

 

[raftman]

If the upper is the serial numbered part like with a sig 556 or SCAR then I would try a polymer lower.
I'm not interested on doing a background check for a plastic rifle lower.

I guess I didn't think of that way. Is it so different from getting a polymer-framed handgun, though? Although ironically I tend to dislike polymer handguns. But I figure AR's are soulless anyways so what difference does it make?

 

[titsonritz]

The only polymer lower I'd consider is the GWACS Cav-15, formally CavArms. Polymer receivers cut to standard forged lower dimensions are prone to crack where the receiver extension threads into the lower, there is simply not enough polymer mass to prevent it. They go into it here in this video just prior to the 2 minute mark.

 

[DirectDrive]

1) Forged AR lowers are cheap to buy, so there's no economic reason to buy a polymer AR lower.
2) The AR was not designed for polymer, so there is a structural reason not to buy a polymer AR lower.
3) And this is why polymer AR lowers are not popular in the marketplace.


DD
Who is now accepting Cabela's gift cards for his excellent internet answers

 

[Stomper]

Poly lowers for an AR are ok if you want a toy (seriously) and only plan to bench shoot with it. As stated above, the rear of the poly receivers are TERRIBLY weak where the buffer tube threads into.

Poly pistol frames are an entirely different application and cannot be realistically compared to on this subject.

 

[Stomper]

Oh, and I don't mean that post as gruffly as it may sound.

 

[notazombie]

I was actually just considering picking up JMT 80% just to try a poly. Hoping more guys with firsthand experience chime in.

 

[raftman]

1) Forged AR lowers are cheap to buy, so there's no economic reason to buy a polymer AR lower.
2) The AR was not designed for polymer, so there is a structural reason not to buy a polymer AR lower.
3) And this is why polymer AR lowers are not popular in the marketplace.


DD
Who is now accepting Cabela's gift cards for his excellent internet answers

My only follow up question is, where/how can you get a complete forged lower for $79.99?

I suppose if it fails in the manner expected, I'll just salvage all the working parts and place them in a more traditional lower.

 

[Medic!]

My only follow up question is, where/how can you get a complete forged lower for $79.99?

I suppose if it fails in the manner expected, I'll just salvage all the working parts and place them in a more traditional lower.

How about a stripped for $48.10?

AM-15 Stripped Lower Receiver - Anderson Manufacturing

 

[titsonritz]

My only follow up question is, where/how can you get a complete forged lower for $79.99?

How about a stripped for $48.10?

AM-15 Stripped Lower Receiver - Anderson Manufacturing

They were just going for $25 not long ago.

 

[raftman]

Poly lowers for an AR are ok if you want a toy (seriously) and only plan to bench shoot with it. As stated above, the rear of the poly receivers are TERRIBLY weak where the buffer tube threads into.

Poly pistol frames are an entirely different application and cannot be realistically compared to on this subject.

Fortunately range toy is precisely the intention.

 

[titsonritz]

1) Forged AR lowers are cheap to buy, so there's no economic reason to buy a polymer AR lower.

In the case of the CAV-15 that is debatable as other parts are not needed, stock, receiver extension, castle nut, receiver end plate, grip, trigger guard.

2) The AR was not designed for polymer, so there is a structural reason not to buy a polymer AR lower.

True for for ones trying make a standard configured lower, not so much with CAV-15 which was designed from the ground up to be solid polymer alternative. In that video I posted above on the WWSD (What Would Stoner Do?) series they give a pretty solid argument on why E.S. may have considered polymer if he was still alive today. In the video the one guy talks about he rifle getting ran over be a truck and was destroyed while another built on a CAV-15 lower survived the run-over, presumably by flexing, that weapon belonged to this dude...History of the CAV-15 Polymer Receiver

3) And this is why polymer AR lowers are not popular in the marketplace.

Fact


DD
Who is now accepting Cabela's gift cards for his excellent internet answers

The only viable reason to consider a polymer lower is weight savings on an extreme light weight build and the only one worth that consideration is the CAV-15, the rest aren't worth the time or money.

 

[saxon]

#1 are you going to do push ups with your gun?
#2 are you shooting rounds that are to much for your buffer?
if no then the bubblegum about them busting is bunkum unless you have proof of one getting busted by just shooting it.....
Omega Arms E3 Gen 2 yes mostly positive except the poly
take down pins
safety
safety detent
not worth a crap replaced with mill spec versions

 

[raftman]

How about a stripped for $48.10?

AM-15 Stripped Lower Receiver - Anderson Manufacturing

I'll keep that option in mind since mine is destined to eventual failure evidently!

 

[11Charlie]

No way I would trust a poly lower especially in a intense situation where your life depends on that weapon to get you back safely!

 

[Caveman Jim]

If the upper is the serial numbered part like with a sig 556 or SCAR then I would try a polymer lower.
I'm not interested on doing a background check for a plastic rifle lower.

Go 80%.

 

[DirectDrive]

#1 are you going to do push ups with your gun?
#2 are you shooting rounds that are to much for your buffer?
if no then the bubblegum about them busting is bunkum unless you have proof of one getting busted by just shooting it.....
Omega Arms E3 Gen 2 yes mostly positive except the poly
take down pins
safety
safety detent
not worth a crap replaced with mill spec versions

They're are actually fantastic.
Don't let anyone tell you otherwise.

 

[Tony617]

They're are actually fantastic. Don't let anyone tell you otherwise.
View attachment 522485

Is that blue locktite on trigger and hammer roll pins?

 

[raftman]

They're are actually fantastic. Don't let anyone tell you otherwise.
View attachment 522485

To be fair, it appears he was talking about an E3 Gen II, and that picture certainly isn't of one of those. Secondly a picture without context makes it hard to tell whether this failed from normal range use.