New Frontier Arms polymer lower receiver failure - Page 1

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[ARCHIVED THREAD] - New Frontier Arms polymer lower receiver failure (Page 1 of 2)

Posted: 5/9/2017 9:43:30 AM EDT

Hey Guys,

Just wanted to post a quick video I put together of my experience with NFA or New Frontier Arms polymer lower receiver. There's a good bit of controversy surrounding the polymer lowers and with good reason.
Take a look and Cheers ??

https://youtu.be/AGS7CXj_j0g

Edit: there seems to be a bit of confusion with my intentions with this video... I am not endorsing polymer lowers, just sharing my experience.

Posted: 5/9/2017 10:06:37 AM EDT

[#1]

FWIW I've had two complete polymer lowers, first one was a Plum Crazy from years ago, other one was a New Frontier.

The FCG on the New Frontier failed and started double tapping after about 1k rounds, mainly shooting corrosive 5.45x39. None of the metal parts showed any signs of corrosion, it was a polymer part that failed. I replaced the FCGs in both polymers with regular steel FCGs. Later the retaining pin on the front takedown pin broke, and I ditched the whole lower.

The Plum Crazy never gave me any issues, spent most of it's life running corrosive 7.62x39 but now it's just a polymer receiver with all steel GI parts. Nowadays with Anderson stripped lowers for $50 and PSA complete lowers for $130 I don't see the appeal. I thought the cheap polymer lowers would be a good option for corrosive ammo but after years of shooting & cleaning it properly from both polymer & aluminum receivers I see no rust on any of them.

Posted: 5/9/2017 10:12:25 AM EDT

[#2]

You don't say....

Posted: 5/9/2017 10:13:44 AM EDT

[#3]

< You know better than to post stupid stuff in a Tech Forum - F >

Posted: 5/9/2017 10:15:37 AM EDT

[#4]

Poly.

No surprise .

Posted: 5/9/2017 10:19:04 AM EDT

[#5]

i got a stripped nfa poly lower years ago. it has a normal fcg in it and i built it as a .22 pistol. havent had any issues with but ive seen them break with rifle calibers and hard use

Posted: 5/9/2017 10:19:58 AM EDT

[#6]

There can only be one.

20170403_090057 by Slick_Rick77, on Flickr

Posted: 5/9/2017 10:31:56 AM EDT

[#7]

Quote History

Quoted:
There can only be one.
https://c1.staticflickr.com/1/728/32985948074_996edb0c10_b.jpg 20170403_090057 by Slick_Rick77, on Flickr

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Agreed. Only one I will touch.

Posted: 5/9/2017 10:34:06 AM EDT

[#8]

Has anyone broken a Tennessee Arms polymer lower? I just got one for my lightweight build. I figured for $35 I would try it.

Posted: 5/9/2017 10:42:35 AM EDT

[#9]

Quote History

Quoted:
Has anyone broken a Tennessee Arms polymer lower? I just got one for my lightweight build. I figured for $35 I would try it.

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Brass thread inserts, but nothing added to the base of the tower where they normally break.
I don't see anything to make me suspect that they would fare any better than any of the other cheap-o polymer lowers.

Unless you're building a super light weight .22, there is zero reason to even consider polymer lowers (besides the CAV / GWACS) when forged lowers are under $50.

Posted: 5/9/2017 12:25:05 PM EDT

[#10]

The area between the buffer tube and the reciever is significanly thicker than an aluminum lower. I plan on using mine for a range toy basically. If anyone actually broke one I'd like to see it.

Posted: 5/9/2017 12:35:51 PM EDT

[#11]

Quoted:
Hey Guys,

Just wanted to post a quick video I put together of my experience with NFA or New Frontier Arms polymer lower receiver. There's a good bit of controversy surrounding the polymer lowers and with good reason.
Take a look and Cheers ??

https://youtu.be/AGS7CXj_j0g

View Quote

In the video you said you paid around $80 dollars for the lower. If cost is one of the main factors since you're beating it up and don't care, why not look into something like the Anderson forged lowers? I want to say my buddy has found those for around the same price if not less. I think PSA also has blem lowers for a decent price as well.

Posted: 5/9/2017 12:36:12 PM EDT

[#12]

Quote History

Quoted:
The area between the buffer tube and the reciever is significanly thicker than an aluminum lower. I plan on using mine for a range toy basically. If anyone actually broke one I'd like to see it.

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3

If this is what yours looks like, then there's still a stress concentration right smack in line with the takedown pin hole just like almost every other polymer lower. The tower itself might be a little thicker, but the break always starts at that hole.

Posted: 5/9/2017 12:45:58 PM EDT

[#13]

Personally, I would never buy or recommend anyone to buy a polymer lower (or upper for that matter) unless it is for a dedicated .22lr build. There has been way to many issues with polymer lowers over the years. Besides, for what you pay for a polymer lower, you can buy a forge aluminum lower and you will be much better off.

Posted: 5/9/2017 12:50:38 PM EDT

[#14]

Poly lowers=

I would not waste my time on 99%.

Posted: 5/9/2017 6:51:08 PM EDT

[#15]

I'll never understand the desire to use a poly lower. It's not like aluminum is heavy.

Posted: 5/9/2017 6:56:50 PM EDT

[#16]

Quote History

Quoted:
There can only be one.
https://c1.staticflickr.com/1/728/32985948074_996edb0c10_b.jpg 20170403_090057 by Slick_Rick77, on Flickr

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+1

Posted: 5/9/2017 7:24:33 PM EDT

[#17]

WOW

Who would have thought!

Posted: 5/9/2017 8:10:42 PM EDT

[#18]

Quote History

Quoted:

In the video you said you paid around $80 dollars for the lower. If cost is one of the main factors since you're beating it up and don't care, why not look into something like the Anderson forged lowers? I want to say my buddy has found those for around the same price if not less. I think PSA also has blem lowers for a decent price as well.

View Quote

You are correct, I won't be purchasing a polymer lower again. The broken one in the video I bought back when I was in college on a budget 7 years ago and if I remember correctly there were not as many cheap options back then.
I know this video is preaching to the choir as even back then when I bought it guys were saying they were shit but I was 20 years old and we all know how that goes.

In defense of the polymer lower, it held up much longer than other stories I have heard of but didn't quite make it the lifetime that a metal one will.

Posted: 5/9/2017 11:19:13 PM EDT

[#19]

Quoted: Hey Guys,

Just wanted to post a quick video I put together of my experience with NFA or New Frontier Arms polymer lower receiver. There's a good bit of controversy surrounding the polymer lowers and with good reason.
Take a look and Cheers ??

https://youtu.be/AGS7CXj_j0g

Edit: there seems to be a bit of confusion with my intentions with this video... I am not endorsing polymer lowers, just sharing my experience.

View Quote

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https://www.youtube.com/watch?v=AGS7CXj_j0g

OP, have you tried some superglue? That will probably seal right back up & you can go back to shooting it. Your other alternative is to call NFA - it appears they have a lifetime warranty, so they should ship your FFL a new one.

That's an impressive record out of a cheap plastic lower. If you really wanted to get fancy w/ it, throw it in a Hera Arms thumbhole stock, that would reinforce the buffer tube boss.

I've got about 5 Cav Arms/Sabre Defense/GWACS lowers @ the moment, but I'm about to start casting my own lowers - my chocolate one probably won't hold up as well as your NFA.

ETA: Welcome to ARFCOM. Got any Legos?

Posted: 5/10/2017 6:16:35 PM EDT

[#20]

Quote History

Quoted:

https://www.youtube.com/watch?v=AGS7CXj_j0g

OP, have you tried some superglue? That will probably seal right back up & you can go back to shooting it. Your other alternative is to call NFA - it appears they have a lifetime warranty, so they should ship your FFL a new one.

That's an impressive record out of a cheap plastic lower. If you really wanted to get fancy w/ it, throw it in a Hera Arms thumbhole stock, that would reinforce the buffer tube boss.

I've got about 5 Cav Arms/Sabre Defense/GWACS lowers @ the moment, but I'm about to start casting my own lowers - my chocolate one probably won't hold up as well as your NFA.

ETA: Welcome to ARFCOM. Got any Legos?

View Quote

Lol you do have an impressive sense of humor sir. Think the superglue is the way to go, would you recommend gorilla glue or some alternative??
You're right the chocolate one probably won't hold up as well but at least when you're in a survival situation you'll have access to much needed calories.

Posted: 5/10/2017 6:26:04 PM EDT

[#21]

Like others have said, only one I would use and I have full confidence in it.

Posted: 5/10/2017 7:18:26 PM EDT

[#22]

Quote History

Quoted: Lol you do have an impressive sense of humor sir. Think the superglue is the way to go, would you recommend gorilla glue or some alternative??
You're right the chocolate one probably won't hold up as well but at least when you're in a survival situation you'll have access to much needed calories.

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Wouldn't recommend Gorilla glue, it expands. I've had good luck with super glue and epoxy on my stocks.

Posted: 5/10/2017 7:46:49 PM EDT

[#23]

Quote History

Quoted:

Wouldn't recommend Gorilla glue, it expands. I've had good luck with super glue and epoxy on my stocks.]

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neither will hold together that lower

plastic is crap for a lower unless that lower was made for it ie cav arms

Posted: 5/10/2017 7:53:26 PM EDT

[#24]

Quote History

Quoted:

neither will hold together that lower

plastic is crap for a lower unless that lower was made for it ie cav arms

View Quote

Agreed ^^^

Posted: 5/10/2017 10:18:05 PM EDT

[#25]

You guys and your plastic guns!

Posted: 5/10/2017 10:39:43 PM EDT

[#26]

Quote History

Quoted: neither will hold together that lower

plastic is crap for a lower unless that lower was made for it ie cav arms

View Quote

While I've got 5 Cav Arms/Sabre Defense/GWACS lowers myself, OP's lower split along the magazine well seam on the front of the gun, and only split after several years of use. Quite likely superglue, 2-part epoxy, or possibly even plumber's cement will suffice for a few more years of use. Unless he just wants to send it in & get a brand new one back from the manufacturer.

Posted: 5/11/2017 9:23:53 PM EDT

[#27]

Sorry if I missed it but what stock is that? It looks pretty good in all the pictures?
Also how much does it weigh in comparison to a complete metal lower?

Posted: 5/11/2017 9:40:30 PM EDT

[#28]

You asking about the Cav Arms Mk 2 made by GWACS?

http://www.gwacsarmory.com/lower-receiver-ar15

1 lb, 5.2 oz. JoshAston built a sub 4 lb AR on one of those.

Trinity Ordnance has black Cav Arms Mk 2s rollmarked Sabre Defense for $60.

Posted: 5/12/2017 5:19:47 AM EDT

[#29]

Right materials and right engineering for the job.
Polymer is probably stronger by weight than aluminum. Just like balsa wood is stronger, again by weight, than the typical spruce-pine-fir used in house framing. But which one are you going to use to make 2x4s to make the frames? a 4 pound piece of balsa will be stronger than a 4 pound piece of oak. But a 4x4 of balsa will be a hell of a lot weaker than a 4x4 of pine. Same concept as polymer and aluminum.
It's stronger by weight, not by volume. It needs to be quite a bit thicker than aluminum to equal the strength.

Posted: 5/12/2017 10:28:40 AM EDT

[#30]

Quote History

Quoted:
I'll never understand the desire to use a poly lower. It's not like aluminum is heavy.

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This. I don't get it. I own one poly lower and it is a Cav Arms lower that I bought back 2002 or so. Back then it made sense from a perspective of cost. Now days? No way would I buy a poly lower. That being said, I also don't understand why these companies do not add a light weight sheet of spring steel or something with the polymer to help beef it up.

Posted: 5/12/2017 11:17:26 AM EDT

[#31]

Some do. There's one brand in particular that puts a brass nut in the buffer tube boss. The AR15Mold.com kit comes w/ a light steel insert that's supposed to reinforce that whole area in the rear.

Posted: 5/12/2017 1:19:04 PM EDT

[#32]

Quote History

Quoted:
Quite likely superglue, 2-part epoxy, or possibly even plumber's cement will suffice for a few more years of use.

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thats not how glues work

superglue has too high shear
pvc glue wont burn into the lower plastic
epoxy wont have enough area for the force of the magwell, unless combined with glass which wont happen inside the magwell

so no they wont work

Posted: 5/12/2017 1:51:03 PM EDT

[#33]

I have an older Eagle Arms marked Cav Arms rifle as my bedside gun. They designed it around the strengths of the polymer lower. The others that slavishly copy aluminum forging aren't anything I would trust.

Posted: 5/12/2017 3:49:53 PM EDT

[#34]

Quote History

Quoted: thats not how glues work

superglue has too high shear
pvc glue wont burn into the lower plastic
epoxy wont have enough area for the force of the magwell, unless combined with glass which wont happen inside the magwell

so no they wont work

View Quote

I've used super glue holding several hundred Legos together as a stock on a 3" 12 ga pump shotgun. I went 24 rounds of 00 buck before my shoulder quit. I took that same stock & mortared it on a concrete floor until the buffer tube bent, but the stock is fine.

http://www.feinsteingewehrwerke.com/loes/stocks/mk8/mk8Prototype24rnds003in.3gp

The magwell is a pretty low stress area. I'll bet OP can super glue it and it will hold for quite some time. If it breaks again, throw some external bits on the front of the magwell, & slather some epoxy on it. Won't be pretty, but I expect it will work.

Posted: 5/12/2017 3:56:05 PM EDT

[#35]

Quote History

Quoted:
There can only be one.
https://c1.staticflickr.com/1/728/32985948074_996edb0c10_b.jpg 20170403_090057 by Slick_Rick77, on Flickr

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Exactly. Take a look at how much thicker the Cav Arms/GWACS lower is in the high stress take-down pin area compared to all the other polymer lowers. When was the last time you saw a picture of a Cav Arms lower broken in half?

Posted: 5/12/2017 4:18:42 PM EDT

[#36]

I would not use superglue on any of my firearms. Just saying. It's a little weird.

Posted: 5/12/2017 4:34:47 PM EDT

[#37]

Quote History

Quoted:

I've used super glue holding several hundred Legos together as a stock on a 3" 12 ga pump shotgun. I went 24 rounds of 00 buck before my shoulder quit. I took that same stock & mortared it on a concrete floor until the buffer tube bent, but the stock is fine.

http://www.feinsteingewehrwerke.com/loes/stocks/mk8/mk8Prototype24rnds003in.3gp

The magwell is a pretty low stress area. I'll bet OP can super glue it and it will hold for quite some time. If it breaks again, throw some external bits on the front of the magwell, & slather some epoxy on it. Won't be pretty, but I expect it will work.

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Maybe glue it, then cut/shape a piece of plastic or something to cover the entire front of magwell and glue that on also. Or it could be glued, then throw on a magwell grip or something. Personally, I would take advantage of their lifetime warranty if that's what they offer. Maybe they won't want the broken one returned.

Posted: 5/12/2017 5:23:41 PM EDT

[#38]

Duct tape.

Posted: 5/12/2017 5:54:52 PM EDT

[#39]

Quote History

Quoted: I would not use superglue on any of my firearms. Just saying. It's a little weird.

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So are steel lowers, wooden lowers, trigger jig lowers, Lego rifle stocks, cast plastic lowers, chocolate lowers... If it's weird, but it works, it works.

Posted: 5/12/2017 6:39:59 PM EDT

[#40]

Quote History

Quoted:

So are steel lowers, wooden lowers, trigger jig lowers, Lego rifle stocks, cast plastic lowers, chocolate lowers... If it's weird, but it works, it works.

View Quote

To each their own. But personally I am not trading any of my shit for something somebody printed out on a 3D printer just to say it can be done.
Just because an inmate in a max. security prison can fashion a "gun" from a piece of tubing, a nail, and a rubberband does not make it a worthwhile endeavor on my part.

But like I said, to each their own.

Posted: 5/12/2017 7:24:10 PM EDT

[#41]

Back in the day, Calvary Arms was recommending a marine grade epoxy for repairs.

IIRC, when it set up it was Pepto Bismol Pink in color

Posted: 5/12/2017 9:48:28 PM EDT

[#42]

The only time I would spend on that receiver is to crush it and toss it. The problem with most injected plastics is that there is usually a release agent mixed in to allow for non sticking in the mold. There is no reliable glue type repair. Craig

Posted: 5/13/2017 9:30:13 AM EDT

[#43]

With the price of lowers right now, I don't see any reason why someone would buy a polymer lower? You buy an aluminium lower and it lasts forever.

Posted: 5/13/2017 11:57:45 AM EDT

[#44]

Quote History

Quoted: With the price of lowers right now, I don't see any reason why someone would buy a polymer lower? You buy an aluminium lower and it lasts forever.

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OP bought his several years ago.

Posted: 5/16/2017 6:58:57 PM EDT

[#45]

Quote History

Quoted:
With the price of lowers right now, I don't see any reason why someone would buy a polymer lower? You buy an aluminium lower and it lasts forever.

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I agree with this.

That being said, I bought mine 7+ years ago when I was in college and the difference in price between aluminum and poly lowers was a lot different than it is now.
Given the parity in price we see now I wouldn't buy one again. I'm also not even sure it's worth the transfer fee and time to try and have NFA replace my broken lower.

Posted: 5/16/2017 9:02:15 PM EDT

[#46]

Seems like poly lowers on an ar15 (556) just dont hold up... what about polymer lowers for pistol calibers? any better luck with those

Posted: 5/17/2017 11:36:54 AM EDT

[#47]

Quote History

Quoted:
Seems like poly lowers on an ar15 (556) just dont hold up... what about polymer lowers for pistol calibers? any better luck with those

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Blowback pistol calibers are harder on lowers than 5.56. Maybe with DI...

Posted: 5/18/2017 8:59:53 PM EDT

[#48]

Quote History

Quoted:

So are steel lowers, wooden lowers, trigger jig lowers, Lego rifle stocks, cast plastic lowers, chocolate lowers... If it's weird, but it works, it works.

View Quote

I was just reading about a guy with a lower made from automotive bushing material and that sounds like a great option given its design for a ton of high stress use.
I believe back in the day it was polyurethane bushings that were used as suspension upgrades for race cars and I'd assume that would be a good medium for a lower that would be next to impossible to crack.

Posted: 5/19/2017 7:48:54 AM EDT

[#49]

Quote History

Quoted:

I was just reading about a guy with a lower made from automotive bushing material and that sounds like a great option given its design for a ton of high stress use.
I believe back in the day it was polyurethane bushings that were used as suspension upgrades for race cars and I'd assume that would be a good medium for a lower that would be next to impossible to crack.

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Looks like it would also be hard to maintain tolerances. It might not break, but if your carrier is binding in the tube because your lower is flexing it still won't run smoothly.