80% lower polymers.....never again.

[D_ninja]

Milled it out per specs and per company recommendation. Placed an AR pistol upper on it and had about 300 successful shots.....then pow!! It literally shattered. ImageUploadedByTapatalk1399357246.409397.jpg
ImageUploadedByTapatalk1399357279.305920.jpgImageUploadedByTapatalk1399357290.439218.jpg

I'll never trust polymer lowers again.
Just want to give you guys the heads up on my personal experience. Note the several fractures in the grip and trigger guard area.

[Jasonaspears]

What brand was this? Any chance the grip was overtightened?

[Eagle Eyes]

From the description of the cracking and the way the plastic looks and shines in the photos I am would guess it was a fiberglass lower and not a true polymer plastic lower (which would be a plastic similar to Glock frame plastic).

[D_ninja]

80% lower polymers.....never again.

I didn't over tighten the grip. Even if I did, the buffer tube region should have held up.

I bought it from Polymer80. It does feel similar to a glock polymer.

[Discogodfather]

No shortage of quality AR lowers out there, find a cheap FFL and buy the best for a grand total of $150. Drill press 80% polymer lowers are, well, awful.

A CNC party is about the bare minimum of quality, these drill press jigs just produce the worst quality imaginable, even in aluminum. Your going to drill out a pocket and grind it with a dremel when the factory tolerance on a CNC part is .005" and get a similar result? I'm 100% pro-home built but this is getting silly.

[Jasonaspears]

I didn't over tighten the grip. Even if I did, the buffer tube region should have held up.

I bought it from Polymer80. It does feel similar to a glock polymer.

Definitely a high stress area. Sorry you had the problems. Maybe the manufacturer will work with you on a replacement.

[Jimi Jah]

Definitely a high stress area. Sorry you had the problems. Maybe the manufacturer will work with you on a replacement.

In aluminum?

[SkyHawk]

I didn't over tighten the grip. Even if I did, the buffer tube region should have held up.

That square hole they molded in for the grip nut was just asking for it IMO. Not sure why the buffer tube tower let go at the same time. Out of curiosity, were you shooting .223 or 5.56?

No shortage of quality AR lowers out there, find a cheap FFL and buy the best for a grand total of $150.

You don't just walk into an FFL and buy a serialized pistol AR lower in CA. If you know of an out of state provider that will ship a lower to CA as a PISTOL and a CA FFL that will transfer it to the buyer as a PISTOL, please share what you've got.

[IntoForever]

What caliber upper did you have on it? I only have .22 on mine.

[mif_slim]

Im sure the 7" barrel had put a lot more pressure on the buffer/tube forcing the buffer to crack the lower.

I have 3 polymer lowers, two were built from factory (Plum Crazy and NFA) and one 80%, I haven't had problems with them yet, but the PC does have well over 6000 rounds with no signs of giving up. The NFA I just got and haven't really went out to shoot it yet as well as the 80%, which will be a dedicated 22 AR pistol.

I'm not speaking for anyone else, but when I got the 80% poly, I just got it for educational purposes. If it breaks it breaks.

[Jasonaspears]

In aluminum?

What do you mean? This is a polymer lower as stated by the OP

[bohoki]

simple thing they have to redesign it to not have the rear take down pin hole

i have this idea to mount it using a little stirrup type fitting clamping to the upper then going through a vertical hole in the receiver under the grip

[-hanko]

No shortage of quality AR lowers out there, find a cheap FFL and buy the best for a grand total of $150. Drill press 80% polymer lowers are, well, awful.

A CNC party is about the bare minimum of quality, these drill press jigs just produce the worst quality imaginable, even in aluminum. Your going to drill out a pocket and grind it with a dremel when the factory tolerance on a CNC part is .005" and get a similar result? I'm 100% pro-home built but this is getting silly.

Thanks for a well-needed bit of reality.

If the folks using drill presses, with or without jigs, or dremel tools, or routers, or whatever, would take a look at an ar lower drawing and note the tolerances...they'd see very quickly that they're lucky to get a finished lower that works at all.

Go cheap, go half-arse, you'll get crap.

If you want a diy lower that will work, try aluminum and a milling machine. If you want the off-paper aspect...you're too late.

[Area 52]

You don't just walk into an FFL and buy a serialized pistol AR lower in CA. If you know of an out of state provider that will ship a lower to CA as a PISTOL and a CA FFL that will transfer it to the buyer as a PISTOL, please share what you've got.

There are none. There are no AR lower recievers on the roster. To SSE, you need a complete pistol.

[DisgruntledReaper]

They supposedly have a LIFE TIME WARRANTY offered on their lowers, they do usually want the damaged lower back.. I would call Poly80 and talk to them......

They are back to making and selling lowers... had to change the red material in the lower to all uniform black material....