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Posted: 10/17/2013 1:02:41 PM EST
What is the quality like and weight difference compared to an aluminum lower? Is there usually any modification needed to make it work?
Link Posted: 10/17/2013 1:05:25 PM EST
Yes you need an X-acto knife to make the LPK fit, and then you can save yourself 4 ounces and 30 bucks. Totally worth it
Link Posted: 10/17/2013 1:12:56 PM EST
[Last Edit: 10/17/2013 1:20:05 PM EST by williewvr]
I have a all plastic Plumcrazy lower. Its 8 oz less than my DSA with a regular LPK.
I've been happy with it, but am going to order a different trigger and hammer. after 5000 rds of 22 the hammer is all beat up.
still usable but starting to look like shot
Link Posted: 10/17/2013 1:18:13 PM EST
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Originally Posted By Alaska511:
Yes you need an X-acto knife to make the LPK fit, and then you can save yourself 4 ounces and 30 bucks. Totally worth it
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and we have a winner . I like your sarcasm , could not of said it better myself.
Link Posted: 10/17/2013 1:24:26 PM EST
A good portion of the weight in an AR15 is coming from the barrel, bolt carrier group, and buffer. An aluminum stripped lower receiver has hardly any weight to it. I do not have personal experience with polymer lowers, so this is mere speculation that I think for a weapon that will hardly be used, and is only used for casual, recreational shooting at a range; a polymer lower would have some merit. But, from the pictures of cracked lower receivers I have seen here online; they have a higher chance at failing compared with aluminum lower receivers.
Link Posted: 10/17/2013 1:26:11 PM EST
Makes an insane light weight SBR though
Link Posted: 10/17/2013 1:33:45 PM EST
Just say no to polymer lowers.
Link Posted: 10/17/2013 2:01:38 PM EST
Originally Posted By jojo4711:
What is the quality like and weight difference compared to an aluminum lower? Is there usually any modification needed to make it work?
View Quote


Crappy.

Little lighter.
Link Posted: 10/17/2013 3:08:51 PM EST
I figured there wasnt much weight savings. Aluminum it is. I dont want to have to worry about dropping it or it breaking from abuse. Thanks for the replies guys.
Link Posted: 10/17/2013 3:12:07 PM EST
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Originally Posted By williewvr:
Makes an insane light weight SBR though
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so your into sbring plastic thats known to break?



op skip the plastic, they are known to break and sure as hell are not worth it
Link Posted: 10/17/2013 3:13:15 PM EST
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Originally Posted By Boomslang64:
Just say no to polymer lowers.
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X2
The only reason they became popular is because of the ban scare madness.
Link Posted: 10/17/2013 3:16:26 PM EST
Buy a polymer, eat a cheeseburger, and the weight is back.

Do some homework on how well they fit, and how often they break.
Link Posted: 10/17/2013 3:20:33 PM EST
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Originally Posted By TaylorWSO:
so your into sbring plastic thats known to break?



op skip the plastic, they are known to break and sure as hell are not worth it
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Originally Posted By TaylorWSO:
Originally Posted By williewvr:
Makes an insane light weight SBR though
so your into sbring plastic thats known to break?



op skip the plastic, they are known to break and sure as hell are not worth it


I wouldn't do it with an NFA or similar, but

Link Posted: 10/17/2013 3:23:30 PM EST
I can buy them all day long for less than 40 bucks.

Never have that's called a clue.
Link Posted: 10/17/2013 3:25:00 PM EST
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Originally Posted By williewvr:
Makes an insane light weight SBR though
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That would be monumentally stupid.
Link Posted: 10/17/2013 3:44:22 PM EST
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Originally Posted By Dan_Gray:

That would be monumentally stupid.
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Originally Posted By Dan_Gray:
Originally Posted By williewvr:
Makes an insane light weight SBR though

That would be monumentally stupid.


Yep, certainly would
Link Posted: 10/17/2013 3:49:36 PM EST
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Originally Posted By JoshAston:


Yep, certainly would
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Originally Posted By JoshAston:
Originally Posted By Dan_Gray:
Originally Posted By williewvr:
Makes an insane light weight SBR though

That would be monumentally stupid.


Yep, certainly would


It would with a Plum Crazy or New Frontier.

CavArms or GWACS is another story. CavArms MKII lowers are as good as they get.
Link Posted: 10/17/2013 3:54:49 PM EST
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Originally Posted By ZekeMenuar:


It would with a Plum Crazy or New Frontier.

CavArms or GWACS is another story. CavArms MKII lowers are as good as they get.
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Originally Posted By ZekeMenuar:
Originally Posted By JoshAston:
Originally Posted By Dan_Gray:
Originally Posted By williewvr:
Makes an insane light weight SBR though

That would be monumentally stupid.


Yep, certainly would


It would with a Plum Crazy or New Frontier.

CavArms or GWACS is another story. CavArms MKII lowers are as good as they get.


I've got an SBRed Cav lower.
Link Posted: 10/17/2013 3:58:58 PM EST
Most of the failures appear to be from someone either attempting to drive a steel takedown pin into the smaller plastic pin hole or doing the look at me I'm tacticool combat roll onto their rifle.
It's only money......and time.....lots of time.
Like any NFA item other than a MG, it's a money pit.
It's as cost effective as a 8 in AOW shottie or any other SBR or SBS
There just toys.
P.s. I'm not a mall ninja, haven't ever dove into cover with a Weapon since I ejected from the US Army and don't plan on it.

Link Posted: 10/17/2013 4:01:41 PM EST
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Originally Posted By williewvr:
Most of the failures appear to be from someone either attempting to drive a steel takedown pin into the smaller plastic pin hole or doing the look at me I'm tacticool combat roll onto their rifle.
View Quote



just google search the images, forcing plastic into a form it was not designed for is a dumb idea and it breaks in all different ways
Link Posted: 10/17/2013 4:04:36 PM EST
Maybe one day someone will write something up on poly lowers and we will get a sticky. Someone should do a why mid length as well.
Link Posted: 10/17/2013 4:19:03 PM EST
[Last Edit: 10/18/2013 3:51:56 AM EST by williewvr]
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Originally Posted By TaylorWSO:



just google search the images, forcing plastic into a form it was not designed for is a dumb idea and it breaks in all different ways
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Originally Posted By TaylorWSO:
Originally Posted By williewvr:
Most of the failures appear to be from someone either attempting to drive a steel takedown pin into the smaller plastic pin hole or doing the look at me I'm tacticool combat roll onto their rifle.



just google search the images, forcing plastic into a form it was not designed for is a dumb idea and it breaks in all different ways

I've noticed most of the I was just moving it and it shattered types only post pcs from one side. I have a feeling that if you had it in your hands then the story might not appear so cut and dry. Having said that I don't think the rear bridge on plastic lowers is properly designed. The three I've personally handled were two attempts to pound a push pin in when it didn't fit and ain't just came apart in the gun bag. When I did some asking around at the range turns out it was leaning against a table cased and someone fell on it. It's easier to say it broke than I had a case of the stupids and broke it. You can do considerable damage to a alum lower with a trigger pin thats not line up with the hole on the off side and a 16 oz claw hammer. That's how I acquired one of my almost Colts. It's got a DSA lower now and the ex owner is 500 dollars smarter. Stark makes a grip just for the I was in a hurry and couldn't be bothered to line up a pin and use a block crowd. Plastics will handle less abuse but I don't believe everything I hear or read and you shouldn't believe it either.
Link Posted: 10/17/2013 4:20:45 PM EST
An average forged lower is 8-8.5 ounces. I do not see where there is enough of a weight savings , to give up that much strength and reliability.
Link Posted: 10/17/2013 7:45:17 PM EST
Originally Posted By jojo4711:
What is the quality like and weight difference compared to an aluminum lower? Is there usually any modification needed to make it work?
View Quote


I have two friends who bought polymer lowers.

On the company's webpage, they had videos of them throwing a rifle around and then firing it (of course, with their company's polymer lower receiver). They did it multiple times, and it kept firing; no problems seemingly whatsoever. I tried talking both of them out of it, but those videos were enough for two of my friends to become convinced.

They both have had problems with their lowers since. One's lower fractured between the buffer retaining pin channel and the opening for the trigger group is. It fractured enough that when he pulled the upper off the lower, the retaining pin jumped out. He returned it to the company, who replaced it free of charge (except for the initial shipping). Still, who wants to have to keep returning lowers?

The other's front upper receiver retaining pin broke in half (because it was made of polymer too!). He bought a metal pin to replace it with. It wasn't a simple drop-in installation though; I had to cut a couple of coils off one end of the detent spring to make the metal pin fit in the polymer lower.

The moral of the story? Pay a few bucks more and buy a metal lower.
Link Posted: 10/17/2013 8:06:49 PM EST
You know why they call Plum Crazy lowers Plum Crazy?
Link Posted: 10/17/2013 8:46:11 PM EST
[Last Edit: 10/17/2013 8:49:48 PM EST by MaverickAA]
My own opinion is buying a poly lower is absolutely crazy. The $20 or so you save by going poly will get you:
a FAR less durable lower
almost no weight savings
questionable fit and finish
more likelihood of needing replacement (there goes your $20, after nics check, not to mention if they someday ban them).

IMHO... just don't. They are an answer to a question no one asked. I applaud "out of the box" thinking, but this is one area where is just plain nuts.

edited to add: and before someone says it, Glocks do well with polymer, but they are also reinforced with a metal chasis which supports all of the friction/load bearing surfaces. Poly AR lowers are not.
Link Posted: 10/18/2013 1:53:23 AM EST
My opinion is that the buffer tube ring in a polymer, along with the pin holes, are the obvious weak points. I have seen the pictures. Now if someone comes up with a reinforced design with some metal/dimensional carbon fiber plate molded into the sides and ring, polymer is GTG. But right now that just doesn't exist.
I do have an ATI Omni that I am going to build into a 22 LR at some point, so I have handled the receiver.
Link Posted: 10/18/2013 2:59:17 AM EST
[Last Edit: 10/18/2013 3:00:18 AM EST by wanderson]
I don't understand why anyone starts a build with a stripped poly lower. You save a few ounces and a few bucks but come resale time you pay big time. Not to say they're junk, I have a Plum Crazy lower on a 7.62x39 upper and a New Frontier for a .22 build (both bought as complete lowers for $110 each), never had problems with either. Also ran the New Frontier on my BCM lightweight 14.5 middy for a year, no issues. The weight savings are not noticeable. For me it's about the cost of a complete poly lower vs a complete aluminum lower, for a budget build/range use toy they're great. But I don't use them on any of my primary/SHTF weapons. And my time building a lower is not worth the 30 bucks you save.
Link Posted: 10/18/2013 3:00:25 AM EST
[Last Edit: 10/18/2013 3:00:25 AM EST by Lancelot]
Topic Moved
Link Posted: 10/29/2013 2:12:08 PM EST
[Last Edit: 10/29/2013 2:13:58 PM EST by Vurbano]
Originally Posted By jojo4711:
What is the quality like and weight difference compared to an aluminum lower? Is there usually any modification needed to make it work?
View Quote

A small piece of sand paper is all you need to work on the magazine release area and the rear takedown pin hole in my experience. The fit will be tight to the upper.
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