June 18, 2020
By James Tarr
Brownells is the the largest retailer of firearms accessories in this country. In recent years it has also started selling complete firearms, but where it has always excelled is in offering gun parts. In the past few years the company has begun selling “Brownells”-branded parts and accessories, made in-house.
Last year it began offering Brownells-branded Glock-pattern slides and barrels, and currently it has two Brownells-exclusive Polymer80 frame models to complete your build.
It seemed to me like it was time to build my own gun as I’d never done it before. I obtained a full-size Polymer80 frame from Brownells, as well as just about every other part I’d need to build my own Glock 17-size pistol—all without requiring the services of an FFL.
If you’re a bit behind the curve when it comes to 80-percent lower receivers, here’s the short version. Per the Gun Control Act of 1968, it is perfectly legal for an otherwise unlicensed private citizen to manufacture a firearm for themselves, provided it is for their personal use and not for resale. Such firearms do not even need to have serial numbers.
However, most people do not have the tools or the skill to manufacture their own guns, which has always been the limiting factor. Enter the “80-percent” companies, of which Polymer80 is the largest.
As long as the frame of a firearm is no more than 80 percent complete when you purchase it, it is still not a firearm. Once it is fully machined, as long as you don’t give or sell this completed frame/firearm to another person, it is not legally required to have a serial number.
Brownells sells several exclusive versions of the compact and full-size Polymer80 frames with the new aggressive texture in black, gray, coyote, flat dark earth and OD green. I secured a black full-size frame, technically the PF940v2. This has an aggressive texture and works only with Glock Gen 3 parts. It sports a flat backstrap and a grip angle closer to that of a 1911.
The complete kit comes with a frame, finishing jig, drill bits and all the P80-specific parts you’ll need for the build. You will still need a lower parts kit—trigger unit, slide stop, magazine release, etc.—to complete the build, as well as a top end. These frame kits normally retail for $150 but seem to go on sale frequently. There is a metal plate in the frame if, at some point, you want or need to add a serial number.
After having gone through the process, I would recommend that unless you’re intimately familiar with the Glock design and can strip a pistol down to the smallest part, you should educate yourself before attempting this build, as even Polymer80s detailed instructions have a few gaps.
Installing the parts in the frame took me more time than machining it. When in doubt, perhaps track down some Glock disassembly/assembly videos online before diving in.
To get this 80-percent frame to 100 percent, you will have to drill three pin holes in the sides of the receiver, mill off excess material from the top of the frame and mill out the barrel block where the recoil spring guide sits. Polymer80 provides three drill bits and a drilling jig, and it recommends the use of both a hand drill and a drill press. You’ll also need a vise to hold the drilling jig.
Most people do not have access to a drill press, and I know people have machined P80 frames successfully just using hand tools, so I decided to do everything using just a Dremel tool and a hand drill.
When drilling out the pin holes, do not go all the way through both sides of the frame. Do one side, then the other. As these pins don’t just go through your fresh pin holes but through steel parts, slight angling errors on your part usually don’t cause problems.
The excess material on the top of the frame is easy to remove. It sticks out above the drilling jig framework and prevents a slide from mating with the frame. You could use a knife or a Dremel with a grinding wheel to remove the excess. Any imperfections will be hidden once the slide is installed.
As for the channel for the recoil spring and its guide rod, you have to remove a circular area, going in from the front of the frame/jig. The material to be removed is clearly marked. The 9mm drill bit Polymer80 provides is exactly the right size, and if you’re using a drill press that’s the way to go.
With a hand drill, however, because that fat drill bit doesn’t have a pointed but rather flat tip, it wants to skip around. So I improvised. I used one of my own drill bits with a pointed tip and a narrower diameter to drill the initial hole, then expanded it to the proper size, using the side of a narrow drill bit as a crude grinding wheel.
Factory Glock frames have the steel slide rails embedded in the frame. That’s not an option with the Polymer80 frame, so it has developed workarounds. The locking block on the P80 frame also incorporates the forward frame rails. There is a drop-in stainless steel rear rail module (RMR) that cradles the trigger housing at the rear of the frame.
Drilling and machining the frame took me 10 minutes, tops, and was shockingly simple. You’ll spend far more time installing the parts into your frame and slide than you will drilling and grinding on the frame.
As for slides and frames, Brownells has something for everyone. Its slides are machined from billet 17-4 stainless steel and given a nitride finish. It has wraparound serrations and is machined internally to factory dimensions. You have your choice of standard or RMR-cut slides. My full-length slide was made for standard iron sights, but with a window machined into the top ($214).
You’ll need a slide completion kit. There are a number of different options available, I bought one from Glock ($90). Every piece and part on a Glock can be installed and removed with a simple punch, and the same is true of the striker channel liner in the slide, but I recommend a channel liner installation tool. You can find them for under $10.
Brownells makes match-grade drop-in barrels of 416R stainless steel for Glocks. These have a nitride finish and are button-rifled so you can use lead bullets safely. They’re offered for G17 and G19—generations one through four—standard length or extended threaded (1/2x28) versions. My standard-length G17 barrel has a suggested retail price of $155.
To finish the frame I had a frame completion parts kit on hand, but if you wanted to buy one, they start at $50 and go up from there. I installed a set of RAM night sights from XS Sights ($140).
Once finished and assembled, I found the slide/barrel fit was really tight. Lubing it generously and cycling the slide by hand 50 or so times before I headed to the range smoothed it out considerably, and live-fire smoothed it out even more. So far, I’ve got 200 rounds through the pistol without a malfunction. It is still tight, which I like, and at least as accurate as any factory-built Glock I’ve tested.
Is building your own cheaper than buying a factory gun? Actually, no, but you get to build the exact gun you want from the ground up, and this is your gun, built by you, nobody else.