Is a forged aluminum or a polymer lower better for an AR build? Any pro/con would be helpful. Thanks

Depends what you building.  Polymer is great for hunting and/or building a light gun. I have a precision AR using the New Frontier Poly lower because the upper and lower has no playback I have a 2 stage trigger in that lower.  My personal ARs I have 5 poly lowers and 3 aluminum lowers.  for me personally I like the NFA poly lowers since they are stiffer than the other poly lowers. 

Shouldn't even be a question

Shouldn't even be a question

Helpful

Forged hands down.  Can certain uses get away with a poly lower?  Yes they can, but forged is still superior. 

Forged hands down.  Can certain uses get away with a poly lower?  Yes they can, but forged is still superior. 

+1

Forged.
The problem with plastic lowers is that they follow the same design as a forged lower and that is a point of failure. There's a pic at the range that shows this. The only other plastic lower that is a total redesign is the CavArms lower.

Forged.
The problem with plastic lowers is that they follow the same design as a forged lower and that is a point of failure. There's a pic at the range that shows this. The only other plastic lower that is a total redesign is the CavArms lower.

only cavarms is redesigned?
or are there others that are not copies?

only cavarms is redesigned?
or are there others that are not copies?

Perhaps there are as I dont track plastic lowers - for I have no desire to own one.
The design Im referring to is one where it incorporates the stock into the lower. The way Frontier and Plum Crazy designed their lower was the same as if they were making it out of aluminum. When I sling up, Id probably crack a plastic lower. Sure I got an offer to replace it if it cracks but why should I buy one under the pretense of a warranty Ill certainly use? Replacing a plastic lower will get old. Not only the repair but reregistering the new plastic lower with HPD. No thanks. All you fanboys can cry me a river but lets face it an aluminum lower is proven and its current price is affordable. A plastic lower should suffice for a.range queen and fondling in a wet dream of a zombie apocalypse or TEOTWAWKI.

My opinion,
If you're building your 3rd or 4th AR, polymer is fine. Triggers are great.

If you're buidling your first or only AR, got to go forged aluminum, or billet aluminum if you want to get fancy ( and expensive).

Depends on your plans for the gun. Is weight and price a factor?  Does chatter from unmatched uppers/lowers bother you? Do you want a gun you can bash in zombie skulls with walking dead style? If price and weight don't matter, go aluminum. If your planning on going into battle with it, go aluminum. For the recreational shooter and hunter, a polymer lower will hold up just fine.

I went with a forged aluminum lower from ar15part.com. Got a complete upper coming too from gunbroker.com. I chickened out on the full build out this time, I really want to give it try on the next one...think I will just slowly get parts under the radar (if you know what I mean) and poof there is a new gun and my wife will almost have no clue. Crafty huh.

for those with an ar which does not fit exactly together, why not just buy an Accurizing Wedge like this one http://www.midwayusa.com/product/518277/utg-accurizing-wedge-ar-15

they are cheap and work well.

as for polymer lowers, has anyone actually seen one fail, it seems like I have heard of 2 or 3 which have on the internet and that's out of how many thousands which have been made/sold/used.  It seems like most come with life time warranties and locally I have yet to see one fail in real life. 

Either way, I'd buy one of each.  They are cheap (usually about 80-100 bucks a piece locally, up to 300 if you wanna get fancy and expensive.  I've seen it for 50 bucks on sale at palmetto state armory but you gotta ship it in to a ffl and its gonna be another 50 by the time your done with that.) and the polymers seem good if weight is the main issue.  If it polymers craps out, just rip the guts out of it and throw it in to the aluminum/metal lower.  I'm surprised no one has mentioned the magnesium lowers as far as weight is concerned although I know some people have concerns about the strength of those as well. 

 

Got a complete upper coming too from gunbroker.com.

what upper did you go with? 

what upper did you go with?

    
 AR-15 Upper 5.56 Matrix Mil-Spec Upper, Stoner BCG, Mil-Spec charging handle, 16” Colt Socom 1-8 Twist barrel, 10” T-Mark hand rail with end cap, YHM Gas block & tube Also came with a nickel boron BCG.

for those with an ar which does not fit exactly together, why not just buy an Accurizing Wedge like this one http://www.midwayusa.com/product/518277/utg-accurizing-wedge-ar-15

The fit of the upper and lower does not affect accuracy - has been proven many times by many experienced shooters. Ask the AMU

The fit of the upper and lower does not affect accuracy - has been proven many times by many experienced shooters. Ask the AMU

oh yeah I know that, it does get rid of the rattle some people don't like though which is what I though we were talking about. 

You can drill and tap for another locking screw that puts pressure on the rear boss of the upper. But it takes longer to take apart.  They also make wedge pins for the front and rear takedown pins but again you need a Allen or screw driver to loosen it and remove the pins.  Accu wedge is not perfect but it helps. I have also stipples the upper recv and that works but doesnt last.

Helpful

You're welcome, just ring if you need more help.

I try to be very supportive of anyone who wants to build their own AR, so in the end I'll end up saying: buy what you want and can afford.  That said, the others raise some valid concerns that you should keep in mind.  Personally, I believe if it is something a life might depend on...the only choice is a forged lower.  I'm sure there are those who will argue "people said the same about Glock, blah, blah, blah..."; well when Glock makes a polymer lower I'll consider it.  Until then, I'll spend few dollars more and deal with the few extra ounces of a forged receiver.

Redesigned or not, it's stuff like this that would always be on my mind...