AR15 polymer lowers, thoughts?

[hminsky]

http://www.joeboboutfitters.com/New_Frontier_Armory_LW_15_Complete_Poly_Lower_p/nfa-lw15blk.htm

I found these very inexpensive lowers for sale, they're made of plastic.

Anyone have any experience with these? It seems like there's some advantages and some disadvantages.
For example, they're more resilient to being dented, but they might break more easily if you whacked the stock sideways on something, etc. It seems like for the price it's worth trying, as I'm trying to build my own custom rifle with a specific upper (18" 3-gun from DPMS)

 

[Baystatesuks]

I have never used a polymer AR lower, but I suspect if they are made of the right polymer they would be tough to break or crack as long as not subjected to extreme temperature conditions.

Their website has no info. about the polymer composition. That would be good to know to determine if you would see expansion or flexing.

 

[jasons]

I did a group buy on them a year or so ago. Still have one. It's perfectly functional, but I don't really see what you gain from having plastic.

 

[Baystatesuks]

I did a group buy on them a year or so ago. Still have one. It's perfectly functional, but I don't really see what you gain from having plastic.

Presumably the goal is to provide the same strength as aluminum at a lighter weight. And it's cheaper. $110 fully assembled with LPK and stock.

 

[jasons]

Presumably the goal is to provide the same strength as aluminum at a lighter weight. And it's cheaper.

It's neither lighter (not significantly anyway) nor cheaper.

 

[Baystatesuks]

It's neither lighter (not significantly anyway) nor cheaper.

$110 fully assembled with LPK and stock is pretty cheap. Most "normal" lowers I have purchased were about $100 stripped. Add in another $50-75 for a LPK and then a minimum of $35-50 for a stock and buffer extension tube, and you are over $200.

I also hear black plastic lowers are killy [as he pats self on back for adventerous cross-threading].

 

[jasons]

Looking back at my notes, it was about 7 oz lighter.

http://www.northeastshooters.com/vb...DATE-post-74?p=1475675&viewfull=1#post1475675


The old group buy thread is here: http://www.northeastshooters.com/vb...6-Plum-Crazy-polymer-lowers-COMMITMENT-thread

I still have the lightweight 20" that I build with my lower. I don't think it's been out of the safe since I did the testing for the group buy.


We paid $89 for a stripped lower with nothing. For reference I'm doing a group buy now on standard aluminum stripped lowers for $61.95.

 

[StevieP]

It's neither lighter (not significantly anyway) nor cheaper.

Yeah, but it'll go through the metal detector at Logan.

 

[dnepro-mike]

cheaper because of so many steps of machining are just not there compare to aluminium. injection molding is very inexpensive process. those lowers should not cost more than 30% of traditional alloy lower. however they do.

buffer tube attachment is the weakest point ob ar15 receiver whether polymer or alloy. ideally both should be rigid enough to contain force of BCG acting on the sreturn spring, but polymer is much less rigid than alloy therefore it WILL deflect under recoil ever so slightly. will it be enough to cause BC to rub on the inside of the buffer tube - is another question, by i tend to think it will.

 

[linedog]

I have a polymer lower. Stripped the threads right out of where the buffer tube attaches. Junk now. Buffer tube still threads in but first shot it knocks its bottom threads out causing the buffer tube ti angle up restricting the bcg from cycling. Never again never again

 

[cekim]

I have a polymer lower. Stripped the threads right out of where the buffer tube attaches. Junk now. Buffer tube still threads in but first shot it knocks its bottom threads out causing the buffer tube ti angle up restricting the bcg from cycling. Never again never again

Stripped while shooting or installing?

I could see stripping it if you overtighten the castle nut. Stripping while shooting? Something else is wrong.

 

[DickWanner]

I have a polymer lower. Stripped the threads right out of where the buffer tube attaches. Junk now. Buffer tube still threads in but first shot it knocks its bottom threads out causing the buffer tube ti angle up restricting the bcg from cycling. Never again never again

Brand? That kind of matters...

 

[center442]

I was at the range a couple of weeks ago with my son and a friend of his. His friend had an AR with a polymer lower. I don't remember the brand, nor do I know if it had a standard LPK or a polymer one. I had never handled one before. The rifle functioned fine. The only thing I noticed was that the gun felt muzzle heavy, but I couldn't honestly say that was a result of the plastic lower. He said he had about 500 rounds through it and hadn't had any problems.

I can't say I would never buy one, but I've still got three or four metal lowers from group buys that I have to put to use before I think about buying another lower.

 

[Romokid]

I have a polymer lower. Stripped the threads right out of where the buffer tube attaches. Junk now. Buffer tube still threads in but first shot it knocks its bottom threads out causing the buffer tube ti angle up restricting the bcg from cycling. Never again never again

You could always make that a dedicated .22lr lower as you don't need a buffer so once the stock is lined up, you could epoxy it in and it should stay that way as there is nothing going back into the buffer tube. Just my .02 as what I would do with it at this point.

 

[ChevyGuy91]

You could always make that a dedicated .22lr lower as you don't need a buffer so once the stock is lined up, you could epoxy it in and it should stay that way as there is nothing going back into the buffer tube. Just my .02 as what I would do with it at this point.

That's what I would do.

 

[AngelKing]

Convinced. I'll stick with the aluminum.

I think Im going to go and get an upper first. I have a yard sale post to trade my workout station for an upper or am just going to save and start there.

 

[dnepro-mike]

i believe cavalry makes good polymer uppers. their's are single piece and come with buffer tube already assembled.
their pretty light. i haven't heard much of them but what i did hear was positive.
$180 for stripped or $270 for complete
a bit too much for plastic lower when complete new frontier traditional looking lower goes for $110

link to their site

 

[Terminator03]

i believe cavalry makes good polymer uppers. their's are single piece and come with buffer tube already assembled.
their pretty light. i haven't heard much of them but what i did hear was positive.
$180 for stripped or $270 for complete
a bit too much for plastic lower when complete new frontier traditional looking lower goes for $110

link to their site

That is probably the only way that makes sense to mold a poly lower. As long as you don't need an adjustable LOP that is a great option.

 

[dnepro-mike]

it looks like these dudes know what their are doing. material is built up exactly where it suppose to and then some. there is no actual buffer tube to speak of and therefore no weak point at the place where it attaches. entire heft of the stock bears the stress which is minimal with this kind of design anyways.
if it wouldn't cost $270 bucks + S&H + FFL Transfer i would love to have one of these. and being in MA fixed stock is more of a advantage than disadvantage.

 

[7.62x39]

I would think that they would at least be comparable in strength to a cast receiver and there are lot of them out there. Their achilles heel was the pivot pin mount. You want to be careful if you've got the rifle broken open for cleaning, there is a fair amount of weight and a lot of leverage working against those small bosses. I've read of more than one that had snapped them off.

 

[dnepro-mike]

I would think that they would at least be comparable in strength to a cast receiver and there are lot of them out there. Their achilles heel was the pivot pin mount. You want to be careful if you've got the rifle broken open for cleaning, there is a fair amount of weight and a lot of leverage working against those small bosses. I've read of more than one that had snapped them off.

i always clean my upper completely off the lower anyways, not an issue.

 

[7.62x39]

i always clean my upper completely off the lower anyways, not an issue.

Me too. I pop it off and mount it in a upper receiver vise block. Then it is solidly mounted and I have both hands free.

 

[FreeWillie]

Given today's climate would you spring for a couple of stripped polymer lowers at $70.00 each as a fall back?