Pros and cons of polymer parts

[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"...