Poly lower saves a pound

[Bang]

A few years ago I bought a New Frontier complete lower. It was for a Bushmaster dedicated .22LR upper that turned out to be a bad design that was a pia to operate which I gave up on. The New Frontier lower has been stashed in a parts box. Yesterday I got it out thinking about maybe eventually putting something together.

I removed a DPMS lower from a Frankencarbine and noted the New Frontier latched up nice and snug. Out of curiosity I weighed the DPMS lower and then the New Frontier. The New Frontier weighed 17 ounces lighter than the aluminum DPMS. Thought I'd post in case anyone has been thinking about a poly lower for weight savings.

[Emptymag]

I remember trying to search for that info and it's not easy to find.
The results I did find showed a larger weight savings than you did, but still not enough to claim "weigh savings" in my opinion.

The single, most notable part that shaves weight is the barrel. A pencil barrel alone will give you a noticeably lighter carbine.
The stock/buffer and hand guard are the other items that will shave weight by choosing wisely.

Not all pencil barrels are the same either.
When I built the lightweight carbine for my wife, I used a Faxon pencil barrel. I also have a PSA pencil barrel upper an the Faxon barrel is visually thinner than the PSA pencil barrel.

Polymer lowers - I can find no redeeming qualities in them vs aluminum unless those very few ounces shaved are what you are truly fixated on.

[Bang]

Darn it, I posted bad info. I re-weighed the two and the poly is about a pound lighter. Sorry folks. Well, anyway, the info is corrected and useful.

Even so, it includes a CAA butt that could be heavier than the one on the poly. The better test would be to remove the butts, but that probably is a difference of few ounces.

[Emptymag]

I thought you were comparing stripped lowers until I read what you posted again.

That's the only valid comparison unless your other attached parts are 100% identical on both lowers.

[MT1]

I thought you were comparing stripped lowers until I read what you posted again.

That's the only valid comparison unless your other attached parts are 100% identical on both lowers.

I thought the same thing based on the wording. I was wondering how there can be a one pound difference when a standard forged stripped lower receiver weighs about 8.5 ounces

[SgtRecon]

Here is an interesting Excel spreadsheet for anyone interested, I stumbled on it doing a search for weights for a recent Colt 653 clone build, its pretty thorough

AR15 Parts Weights Database:

https://docs.google.com/spreadsheets...#gid=102399689

[Emptymag]

Here is an interesting Excel spreadsheet for anyone interested, I stumbled on it doing a search for weights for a recent Colt 653 clone build, its pretty thorough

AR15 Parts Weights Database:

https://docs.google.com/spreadsheets...#gid=102399689

Does "M" indicate a stripped lower on that chart and "U" stand for upper?

It's a little confusing

[Bang]

Since the polymer lower came with a FCG installed, and I bought it thinking weight savings (among other reasons), I think weighing the two with FCGs installed makes sense. The steel or MIM parts in the aluminum lower are expected to be a little heavier than Polymer FCG parts in the polymer lower. Comparing the two in usable complete configurations is also reasonable to me.

[alpacaheat]

I've looked into poly lowers but long-term durability is my concern with an AR.

[Bang]

Just some ruminations...

As far as the molded lower, I don't think fracturing it is a concern. Enlarging or elongating of holes from FCG pin rotation, a long leap maybe.
Heat resistance in an extended fire fight, hopefully it will never be something to consider or experience. Wearing of parts such as magazine latch and hammer/sear surfaces, don't know, but the latest NFA polymer lower will accept all mil-spec metal parts. If changing to a metal FCG, just have to change the safety to a "real one".

I believe the early NFA lower wouldn't accept drop-in triggers. Don't know about the LW-4.

It looks like the original New Frontier Armory polymer lower which sold for $109 is no longer available. NFA now markets a later gen (LW-4) for $129. And clling it polymer may be incorrect. NFA is describing it as carbon fiber.

Complete with mil-spec butt, it weighs 28.4 ounces. One writer mentions a heavy barrel combined with a polymer lower and butt can make for a weird-handling front-heavy gun.

https://www.newfrontierarmory.com/pr...milspec-stock/