Again, might be somewhere else but being a newbie my searching capabilities are limited on the forums.

It seems that composite lowers are cheaper and can withstand the wear and tear of use better...what am I missing here?  Is it that easy?

Thanks again for any and all help.

Where did you read that composite will hold up better than aluminum?

All the M16/M4's in use overseas are using a standard aluminum lower for a reason.  I would only use a composite lower on a dedicated 22lr build...

Makes sense that it would hold up better against the elements...I liken it to plastic vs. metal outdoors.  Plastic lasts forever.  I might be oversimplifying it.  I Would love to get some thorough pros and cons though.

Aluminum doesn't rust and handles the "elements" very well.


No it doesn't.
Ultraviolet radiation from sunlight breaks plastic down. Different plastics behave in different ways although they're using a composite at Plumbcrazy which would be much tougher than garden variety plastic.
 
Composite lowers are not generally accepted by the shooting community for serious weapons especially when good aluminum lowers are available at low price points.
A composite lower would not protect the shooter as well as aluminum in the event of a kaboom.  

I seriously doubt that composite will hold up as well at the major point of stress as aircraft grade aluminum. Especially at it begins to break down.

Would that be the same material that I had to file out of my magwells on my 10/22s to get the mags in/out after 10 years or so.
Actually I do not know enough about the polymer lowers to compare them to aluminum lowers.
When I start hearing about the guys who carry the AR platform for a living using polymer lowers my interest level will probably go up.

Unfortunately, there aren't any lowers on the market, except the CarArms lowers, that don't have some serious issues and concerns with durability.  Even under normal use.  The reason the CavArms model is different is because it is a drastic redesign that takes into account the weaknesses and strengths of the different polymers on the market.  Trying to force a material into a design is was not made for is a poor choice if you want it to last.  I also have to note that not all polymers or composites are made the same.  Most items made from polymer meant for durability are filled with nylon fiber, kind of like adding aggregates like gravel or rebar to concrete.  Most of the budget plastic lowers don't do this.

I'll be the first to admit that I don't own a Plum Crazy or any other polymer lower, but that doesn't make my point any less valid.  I have seen reports of them breaking, especially around the buffer tube area and front lug area under normal use.  One of the improvements between the M16A1 and A2 was the addition of material around the buffer tube ring, so its pretty safe to say they found problems even with high quality aluminum being durable enough for use.

ok, after more research I think I might agree that the aluminum lower is best.  I suppose it does make sense that the composite/polymer lowers may crack under stress.  I saw the links to the other posts about plum crazy lowers cracking too.  I doubt the aluminum will do that.  I'll be more than happy to spend the small extra to get something that should last a bit longer.

Thanks guys,

Just my honest opinion...Leave the composite lowers for 22s!  Plum Crazy and a Chiappa 22 upper...Oh yeah!  9MM?  Anyone?  

I have the composite S&W MP15/22.  Pretty neat, but I don't think I would invest in the lowers just yet for AR-15s.  Google Plum Crazy and AR-15...You can read a few posts that have had catastophic endings.  I am hoping the technology will catch up, and it probably will.  They MUST put some sort of embedded steel/aluminum structure...Or just lined.  It has to happen for it to take the forces exerted.  The companies WILL figure it out hopefully before they go broke.

I love to see technology to expand...That's what makes America great.  I just don't see it yest on the 2.23 or higher area yet.

Don't waste your time or money with composite/plastic lowers.  These days you can find forged aluminum lowers which is what military specifications call for at a price starting around $50.00  I'd take a mil-spec aluminum lower vs. a composite lower any day.  There's just no comparison.  PSA (palmetto) has a deal on lowers starting at $49.95  The normal price is $79.00 which is still a great deal.  YOu can pretty much spend as much or as little as you want on a lower.  Some cost significantly more.  Somebody here recommended YHM (Yankee Hill Mfg).  That is what I bought for my first build and I'm very happy with it.  My second build I went with an Aero Precision.  Haven't had any sticky mags problems with mine though.  Although I prefer my YHM, I'm very happy with both of these lowers.  Hope that helps.  Good luck.

Yeah, composite lowers are junk, just like Glocks.

It's too bad the SCAR, ACR, ARX, and other low class  junk rifles are coming out with composites. It's obvious the corporate profit mongers are foisting off inadequate materials on  the fighting soldier. No wonder SOCOM stopped buying the SCAR.

Oh, yeah, they still buy the .308 version. Hmm, maybe composite lowers CAN take the abuse. Maybe composite full stocks on rifles are OK.   Maybe all the new pistol designs in the last 25 years are working just fine.

You think?

It's been proven that forged aluminum was fine in the day, but an extruded upper and composite lower will do the job. After all, compared to stained walnut, a composite stock is far superior, and in the AR, the lower isn't stressed by  holding together parts of the receiver to contain the cartridge. That's all done by the barrel extension.

We don't need forged aluminum,  quality composite stocks have long ago proven their worth on the HK91 and many others. The Improved Carbine project is just as likely going to be a composite lower with extruded upper - and a quality AR could be made the same way, and cheaper to boot.

An extruded monolithic free float upper with rail and handguards? Sure, why not? Composite lower with drop in trigger? AR already can take that. All the lower does is hold the stock and upper together against the pressure of the human body, worst case is getting used as an expedient ladder by a soldier in full battle rattle. If anything, composites can take more abuse than a thin tube screwed into the back of the lower. Check that joint, it's not robust at all - yet it is stronger than the wrist on a Garand or M14 stock, wood OR fiberglass. I've seen those shatter when abused.

I've got no problem with composite stocks, the LCP, Glock, and Remington 700 work just fine. Composites molded 20  years ago are still  going strong, and  that's nearly the service life of the weapon. Composites from  45 years ago were used in the M16, nobody thinks they are dumb now.

Composite stocks ? Yes.
Composite AR receivers ?  Good luck with that.

Composite works fine if it's designed that way from the beginning.  Replacing aluminum 1 for 1 with polymer doesn't work so well.  The CavArms works fine, it was a significant redesign of the AR lower.  The Plum Crazy and Hesse lowers don't work so well, they didn't redesign anything, just replaced aluminum with polymer.  For polymer to work it has to be designed with the strengths and weaknesses of polymer in mind.

Tirod....maybe you should change your name to Tirade.  Sheesh!  Don't blow a head gasket man.  It's not worth it.  As pointed out by the others, polymers, composites, carbon fibers can be used successfully in a variety of applications.  It's now widely used in both aerospace and automotive manufacturing, just to name two examples.  The point is it hasn't worked successfully in the AR platform.  There's a reason for that.  The other weapons you mentioned were designed to utilize lightweight materials from the beginning.  

I will buy a carbon fiber lower when they make one !


that is all

Bushmaster (previously Professional Ordnance) has been making them for years and years...

http://www.bushmaster.com/catalog_carbon15_index.asp

Are those actual woven carbon fiber or granulated and sqirted into a mold type carbon?? Cuz I want the woven

I never really looked at them closely

That would be a question to ask bushmaster, I guess.

What kind of thread is this without pics

Both the 9mm and 6.8 put more stress on the lower than 5.56 does.





Colt 6450 upper
ARP 6.8 upper

I was the owner of a Plum Crazy lower. It failed (meaning the composite of the lower broke at the buffer retainer) with less than one hundred (100) rounds through it. It took a month to get a replacement. I sold the replacement last saturday to get parts for a real AR15 rifle.