Pros and cons of polymer parts

[Jimbo Slice]

With the prices dropping lately, I was thinking that I may try to tackle an AR build. I see some places have polymer lowers at far cheaper prices and was wondering what the pros and cons might be to using one of these in my build.

I'm sure I could go to AR15.com or whatever and find mountains of opinions on the subject, but I thought I would run it by a select few first. Thanks in advance. :D

[LEAD POISON]

Plastic is for squirt guns made by matel.

[Jimbo Slice]

Plastic is for squirt guns made by matel.

Yeah but... <scratches head>... isn't that kind of what we're talking about in the first place?

:)

[Orlando]

I honestly dont see a reason for a plastic lower, heck what can you possibly save a few ounces in weight??? My concern is longtime durability of the hinge point.
Plastic lowers may be cheaper but I would rather pay the $$$$ and get a real lower. JMO

[Jimbo Slice]

I honestly dont see a reason for a plastic lower, heck what can you possibly save a few ounces in weight??? My concern is longtime durability of the hinge point.
Plastic lowers may be cheaper but I would rather pay the $$$$ and get a real lower. JMO

Here we go. You see, I didn't even think of the hinge point between upper and lower. I just have to wonder why anybody would buy a polymer lower if they did indeed suffer from durability issues.

Does anybody know of any horror stories?

[Orlando]

I am sure they are reinforced with a metal sleeve but I still just dont see a reason for them, but I dont own a Glock either
I suppose under normal use they are fine but how much $$ are you actually saving?

[LEAD POISON]

The way things are going,In a few years your going to have pay more for a quality all metal firearm.
I have metal guns that are 85 years old. Some with plastic grips,most with minor cracks,chips.Plastic gets old too.Will these Plastic guns last half that long.heat & cold ware and tear.

[timshufflin]

I know a few great reasons for a polymer lower,
you can print them when the feds infringe a bit more and tell them to go stuff it
they are cheap, you can keep buying them as you fancy
they are a little lighter

[cuppednlocked]

I would use one in a heartbeat for a rimfire build.

[grumpyoldretiredcop]

Plastic lower for a rimfire or range toy, sure.

Plastic lower for a rifle intended for serious social purposes? Not for me, thanks... not until those pesky breakage issues are cleared up (or my son-in-law gets his 3D printer up so I can make lots of 'em and tell Sacramento to stuff it).

[Eli]

From what I've read, these work well and last: http://www.lw15.com/
Not sure I'd use one though...

Eli

[Orlando]

Ya but they havent been around long enough to know what long term reliability is?

[mixmaster]

I have one in 9mm and don,t see what the big issue is. I also have a Glock duty weapon and I have had it for 14 years now and no problems with it. I do not care for Tupper wear but it works. I got a COMPLETE receiver for under the price of a stripped alloy. While the questions float around I will enjoy mine and maybe when it wears out the alloy ones will be priced lower. How many times do you take one down that would cause the pin to wear the receiver? I have replaced AR receivers because the pins are walking out but never for the take down pins.Forgot to mention mine has a lifetime warrantee
Mix

[precision32]

I've built two rifles using poly lowers. Both seem to be holding up well. I do know that a poly lower will take misplaced hammer/punch blows better than alloy.

Just what loads do the lowers take?

I do use non-rotating pins, but I do that on my aluminum lowers also.

[Paltik]

I've heard multiple anecdotes of polymer lowers failing much sooner than would be expected, usually around the buffer tube. The key, I hear, is to get a polymer lower that was designed as a polymer lower, not a lower based on an aluminum design.

[grumpyoldretiredcop]

Mixmaster, please bear in mind that the Glock frame has a metal insert that bears slide and recoil forces, something that polymer AR lowers lack. If someone were to come up with the same sort of embedding process for polymer AR lowers, I wouldn't have a worry in the world about using a polymer lower for serious business as I trust my G19 carry pistol.

[ttwn0324]

I can't think of any pros. A lot of cons though. But, my experience with them is from the early days. They like to fail around the buffer tube and rear take down pin. Which, I think is just a weak spot no matter. This is the main spot to look at and ask about.

[NE450No2]

Plastic scares me... Here is why. All plastic things I have ever known of eventually get brittle and crack or break... If plastic gets hot it gets soft, then melts.
If it gets extremely cold, it cracks, and breaks. Certain chemicals, like oils, get on it it cracks, breaks and melts... Sunlight decomposes it, and it cracks and breaks...
A flintlock from 1776, if it recieves even average care will still work today... Even the aluminium M16 will last for thousands and thousands of rounds.

In 1982 I was issued an original full auto AR15, made around 1963. I used that rifle for several years and then my partner used it for several more years. It shot many thousands of rounds, we replaced the barrel as needed. I retired in 2006 and it was still going strong.

I just do not trust "Plastic"...