Making handgun frames out of plastic is nothing new, and just about every manufacturer in the market today has mastered the craft of producing a functional polymer frame that's lightweight, robust and long-lasting. Up until this point, adapting polymer to America's favorite rifle however has been a different story. For many, a polymer ar lower seemed outside the realm of reasonable possibility. 

Taking the familiar shape of the AR15 lower receiver and rendering it in plastic usually results in a catastrophic failure at either the buffer tube threads, or through the rear takedown pin hole. The different mechanical properties of aluminum and glass-filled nylon virtually guarantee it, and reinforcing these areas usually only delays the inevitable.

Polymer AR Lower History

Colt first recognized this in the 1960s, and produced a polymer version of the M16 which integrated the buffer tube and stock, along with the receiver in an attempt to address this shortcoming, but it never went in to full production as they already had the tooling set up to make Stoner's design in alloy. Cav Arms and later, GWACS Armory riffed on this idea, and for a short while this century made polymer AR receivers which at the time were well-received by the shooting community. Cav Arms landed in hot water with the ATF and GWACS disappeared from the face of the earth after letting their FFL lapse, which left a hole in the market. Enter KE Arms.

KE Arms STRIPPED KP-15 LOWER RECEIVERS POLYMER $109.99 at Brownells

By teaming up with Ian McCollum and Karl Kasarda from InRange TV, the group set out to address some of the shortcomings of a polymer AR lower and improve on what came before. We got a first look at serial number 00003, which is a pre production specimen and very much a work in progress.

First Impressions

Unfortunately, we couldn't get our hands on serial 01, but this will do

We were prepared to be underwhelmed and expecting something flimsy and delicate. And we were wrong. This is a seriously chunky and robust lower – it feels like you could run it over with a garbage truck and the truck would come off worst for the experience. Because it's a pre production unit, the surfaces are shiny and show some of the internal structure, which hints at reinforcing webs throughout the buttstock area. “We're still refining the mold at this time, and most of the surfaces of the production guns will have a rougher, sandblasted texture,” said KE Arms' Russell Phagan, who is leading the project. (Full disclosure; Phagan has written for RECOIL in the past).

There have been a few small modifications to the AR's architecture in order to accommodate the change in materials, but the layout is basically the same one we're all familiar with. For example, the safety selector's in the same location and operates identically to that in an aluminum lower, but its detent is now inserted from the top, rather than being held in place by the pistol grip. “By molding the entire lower as a unit, we've eliminated seven components and made it much stronger,” claimed Phagan.

At only 25.5 ounces for a complete lower, the KP15 is likely to find favor with anyone building an ultralight AR

This is pretty typical for a carbine lower – almost 10 ounces heavier than the KP15

One of the benefits of a polymer lower can be seen when you put it on the scales. In comparison to a standard carbine lower, this one comes in around 10 ounces lighter, though it does sacrifice the ability to adjust length of pull. “We found that in the majority of cases, this wasn't such a big deal,” says Phagan. “Most people end up setting their collapsible stocks at the A1 length and leave it there. Maybe Stoner was on to something.” For those who want a longer LOP, KE Arms plans to offer spacer kits to bump out the butt pad.

We plan on shooting the hell out of the KP15 polymer AR lower in the upcoming weeks, and will report on the final design when it goes into production in early September. Brownells is currently accepting pre orders for anyone who wants to get in on the action, and at an MSRP of 90 bucks, it may be worth a shot for those looking for something different for their next build.

KE Arms STRIPPED KP-15 LOWER RECEIVERS POLYMER $109.99 at Brownells

More on the KP-15

• Find more details from KE Arms' first announcement here.
• We took the KE Arms KP-15 full auto. Watch on RECOILtv.
• KE Arms KP-9, Monolithic Polymer Reciever in 9mm. 

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