Polymer 80 80% Pistol Frame V.1

Completing an 80% Glock Lower

No doubt you've seen 80-percent AR-15 lowers. They've taken many forms over the years from simple forgings to billet pieces in various states of completion. If the Bureau of Alcohol, Tobacco, Firearms, and Explosives (BATFE) has a special calculation as to the difference between an 80-percent lower and an 81- or 82-percent lower, they haven't shared it with us.

By and large, what the BATFE considers a firearm seems mostly to be a subjective measure. There've been incidents in the past where a lower was deemed kosher by the BATFE — until it wasn't. A notable example of this in the AR-15 world was the EP Armory 80-percent lower that utilized two different colors of polymer: one that needed to be drilled and milled out, and the other that didn't. Another was an “AR flat” that consisted of slabs that could be drilled, tapped, and screwed together (a weldable version is still allowed at the time of this writing).

It was only a matter of time before we saw 80-percent Glock lowers for sale. There've been some scratch-made Glock receivers built in the past, with materials ranging from sheet steel to converted airsoft lowers (the latter was harder than you'd think). Polymer 80 first wet its feet with AR-15 lowers and more recently moved into the world of Glock.

There've been a few third-party complete Glock receivers, all with varying levels of success and failure, but Polymer 80 has produced the first commercially available 80-percent: the Spectre. Polymer 80 started with a standard 9mm/40 frame, suitable for constructing third-generation Glocks (17/17L/22/34/35) in a variety of colors. Likely by the time of publication, they'll have a Glock 19-sized option available.

Though it might look like a lot of work to the uninitiated, there's not too much required to bring this project to completion.

For $160 you get the incomplete frame, a disposable jig, mill and drill bits, and a proprietary locking block. All the small parts and pieces you'll have to provide yourself, as well as the slide and barrel assembly. A quick jaunt to Gunbroker and other online auctions shows complete Glock receivers for as low as $165, so some of you may be asking “why bother?” Why not? Not every DIY project one undertakes has to be done solely for cost savings; the pure pleasure of working with your hands is enough for many. Still, there may be those worried about prospective bans, and perhaps more who simply like the idea of having a legal, homemade gun for personal use (subject to your state laws) — like the Ghost Guns California State Senator Kevin de Leon is so worried about.

The parts you need to complete this build include the following:

Complete slide assembly, including barrel and recoil spring
Trigger and trigger bar
Rear housing assembly, including trigger spring, ejector in appropriate caliber, and connector
Magazine catch and spring
Slide stop lever
Slide locking lever and spring
Pins (trigger, locking block, and rear housing assembly)

Complete slides are readily available online and can ship directly to your door.

Going through our box o' parts resulted most of what was needed, and the rest was obtained for under $20. The magazine catch spring, one of the simplest parts, was the hardest to source. For those without a box o' parts, some aftermarket shops have started selling receiver completion packages. Lone Wolf Distributors currently has them listed for $79.

For complete slides, Polymer 80 sells their own, and auction sites like GunBroker are a safe bet if you want OEM. Some resellers seem to do little more than separate the slides and receivers and sell them separately. Of course, a ton of aftermarket slides and barrels are out there. We decided it would be best to go with an OEM slide to minimize possible issues with fitment.

The Spectre frame isn't just a facsimile of the OEM model. It has a larger gripping area, no finger grooves, an integral beavertail and magwell, and a full Picatinny rail. It's also available in a variety of colors. Just giving the kit a glance over, it doesn't seem like there's actually too much to do — mill off the front bits that stick out, drill three holes, and machine the rail in the back. The rail is what we expected to give the most trouble, in no small part, because while a traditional Glock handgun frame is mostly polymer, the rear rails themselves are metal.

The Polymer 80 webpage has links to video instructions, which we dutifully watched for 30 seconds before deciding to just dive right in. Let's talk about how we did, where we messed up, and how to avoid the same pitfalls yourself.

You can see why a clamp is recommended to keep the jig tight around the frame.

While we have access to a milling machine, in order to make this more of a “home build” we decided to use some more common tools. An old 12-inch tabletop drill press, Dremel tool (of course), a drill press vice, and some clamps. The idea was to put the end mill bit into the drill press, secure the jig in the vice, raise the drill press table itself to achieve proper height, and move the vice itself around to perform the milling. The jig wasn't a perfect fit, so the clamps ensured it fit tightly around the incomplete frame as we went.

We're talking plastic here, so you don't have to mill this area down in 40 passes like you're working something like hardened steel. Still, a few slow passes makes for much cleaner work. We did bobble it a couple times and you can see the scars on the jig itself. Oh well, it's single use anyway.

Go slow if you want a job clean enough to show off to your friends.

When drilling the holes, ensure you're perfectly lined up — it's probably best to drill each side separately. One of the holes we drilled through without being perfectly level, making for a larger headache later. Then came milling the rear rails. While you'll be cleaning up this area later during fitting, this isn't something you want to mess up. Go nice and slow.

And that's it! Well, almost. The actual machining operations are fairly simple, but parts fitment can be more time consuming. Start with a stripped slide to check for fit. Use a flat file to make modifications as required, but continue checking for fit often — you can always take off material, but adding it on is a different story.

Drilling and Dremeling, and not much more.

Next, you'll want to install your small parts. The included locking block is the first to go in. It'll absolutely be tight, but don't remove any material. Line it up and tap it in. From there you might think you can install your trigger, but you'd be wrong. The holes themselves are undersized, and there are reports by some of frame cracking. Some builders have used larger bits, but we used a hand reamer until the pins went in without an undue amount of force.

After your pins are installed, bust out your Loctite or other thread locker, and secure the included machine screws to ensure your locking block stays in place. Your slide locking lever and spring go in next.

A flat file is perfect for final fitting.

Use the best tools you can, but you don't necessarily need the best tools.

And check fitting. Again. Start again with a bare slide. Then, an assembled slide without barrel. And finally, with the barrel. Fitting in steps allows you to isolate and diagnose any potential issues with the parts and your machining. Don't go nuts and take off too much at once.

Though it took a bit of time, we felt fairly confident it would be easier to do another. And with fewer tools. So we did. Though we didn't have time to grow a scraggly beard and find a proper cave to work in, we settled for not showering for a day and doing everything on a dirty basement floor. You gotta set the mood. Glocks are like AKs in that no matter how dicked up they are, there's always some assh*le who (drunkenly) says, “I bet it still shoots good!” Let's test that.

Another Spectre was obtained, this time in FDE. That desert color also helped with the mood. For tools we went with a Dremel (naturally), cordless drill, and a clamp. In a pinch, you could probably just use the cordless drill. Sanding drums on the Dremel made quick, albeit dirty, work of the front area that has to be milled out. The rear rail and the holes were done freehand. To fit the rails a stripped slide and hunk of wood were used to rough it out. Total time? Twelve minutes — with most of that being swapping out sanding drums and snapping photos.

Assembled, she's ugly as hell. But, do they shoot?

The beavertail is a welcomed touch.

The first time shooting any home build gives us pause. Yes, people have done this before, but we can't help feeling like we should be using a vice, a string, and a ballistic shield. I settled for extending my arm and turning my head to the side — all that was missing was a hearty “Hold my beer, and watch this!” We wish we could report that both pistols were phenomenal right out of the box … err basement? Ultimately it took a couple range trips along with some tinkering before they became more reliable. The black Spectre suffered from ejection issues and the FDE would fail to return to battery.

With a generous amount of lubrication and rounds sent downrange, the FDE Glock self-corrected. Apparently a rushed Dremel job doesn't make for the smoothest of actions. Huh. The issue with the black Spectre was a bit more nuanced. There was some play in the rear trigger housing, likely due to mucking up the pin hole a bit, Ultimately we ended up shimming it in place to restrict movement, though there are still some phantom malfunctions to track down.

All told, the Spectre was a fun afternoon project with some more work on the back end at the range. Don't be like us — watch the official videos and use the best tools that you have available. But even a Dremel can probably do some excellent work if you have a steady hand and aren't racing the clock. In terms of receiver completion, this is a very easy project. With the frames being polymer, you can also burn and stipple to your heart's content, or until you mess something up so badly you have to scrap the whole thing.

The longevity of the polymer rails at the rear of the receiver is our main concern, and the only way to see if it holds up is to continue to shoot the hell out of it.

Price
$160
URL
www.polymer80.com

This article and more can be found in DIY Guns: RECOIL Magazine's Guide to Homebuilt Suppressors, 80% Lowers, and More.

Polymer 80 80% Pistol Frame V.1 – The Ghost Glock

Completing an 80% Glock Lower