The Ultimate DIY Home Improvement Project

The 80 Percent Arms GST-9

Interchangeable magwell funnels let you choose between a GLOCK 19
and GLOCK 17 frame geometry. Swapping out these accessories requires
nothing more than pushing out a couple of pins.

The rugged polymer jig zeroes the holes and sets some limits
when removing the superfluous bits. A series of bolts sandwiches
everything together securely.

The GST-9 pistol from 80 Percent Arms is a home-build kit, allowing you to construct a top-flight GLOCK-style 9mm handgun legally in your garage. The end result is as cool as Steve McQueen’s sunglasses, as lethal as Chuck Norris’ farts and as rugged as John Wayne’s jockstrap. Move like you mean it and you can go from a box full of parts to ringing steel in maybe half an hour.

The GST-9 is a superb defensive pistol in its own right. Extra cool upgrades come standard, and the chassis offers certain high-performance options not available in a factory pistol. You also get the personal satisfaction and security of having built it yourself.

You can finish out one of these guns with nothing more complicated than a hand drill. A Dremel grinder and drill press make things quicker and easier, but hand tools and a little sweat produce a comparable result. If you can keep up with a 6 year old building Legos, you are overqualified for this project.

This semicircular material needs to come out. The jig wraps around
everything that needs to stay to help keep you from going too far.

The jig kit has everything you need to secure the frame in the completion
jig along with the necessary tool bits. They even included a little extra
hardware, just in case. That’s always a nice touch.

The end result is pretty darn cool.

Life Lessons In Firewood

The temperature was in the single digits, and I had some long-forgotten chore in my workshop. My home-built wood stove began life as an old oil drum. When properly stoked, the thing puts out more heat than a nuclear reactor.

I’m a pig, so I just pile up my wood scraps during the hot months for use in the winter. However, this winter had been longer than most, and my scraps were about gone. In desperation I found an old 4×4 half buried outside in the muck. I wrenched it out of the mire and ran it through my chop saw.

There resulted a tidy stack of roughly foot-long sticks of firewood. I poured a capful of motor oil over a mound of sawdust to get the party started. When I reached for my first stick of rotten 4×4, I had an epiphany.

The end of the old nasty piece of lumber sported a beautiful crimson hue. Cedar is mightily resistant to rot and therefore makes a fine fencepost. I had not erected such myself, but there had been a previous homestead on the site perhaps a century prior. This old piece of well-aged cedar was obviously left over from that earlier era.

All thought of my project now forgotten, I ran the piece of old cedar through the table saw and cut it into uniform strips. Two hours later I beheld the most adorable little jewelry box, lovingly crafted out of a 100-year-old fencepost. Once varnished the box veritably glowed with that inimitable red color and smelled like the arithmetic mean between Christmas and heaven.

That holiday season, in addition to the obligatory shiny baubles, my long-suffering bride also received the handcrafted jewelry box. This gift cost me quite literally nothing — I pried the raw material out of the ground — but it nonetheless eclipsed all the rest. My wife’s little box was something the man who adored her had conjured with his own hands. Were you to canvass the globe, there is not another anywhere quite like it. Walmart Tupperware would yield comparable service, but not with nearly so much style.

In many ways, the GST-9 is comparable. Your local gun emporium is awash with sundry plastic pistols at a variety of price points. However, when you finish building the GST-9, you are intimately familiar with every pin and spring. The end result is a holy melding of the raw material from 80 Percent Arms and a modicum of skill from the builder. To subsequently pack such a unique roscoe for real is a rarefied experience indeed.

Snip four little tabs like these off with wire cutters or a cutoff wheel
and then smooth down the excess. There are several ways and a
variety of tools available to accomplish this simple exercise.

This is what’s left after snipping off the extraneous tabs.
Now just flatten out the excess and you’re good to go.

After using it to bore a hole in someone’s skull, Will used this
simple disposable medical hand drill to do one of his frames.
Take your time and the end result is indistinguishable from
the same thing drilled on a drill press.


According to federal law, if you build a firearm at home for your personal use and don’t plan to sell it you need not serialize the frame or even tell anybody. Some of the less durable among us take umbrage at freedom on such a rarefied scale. However, in our nation of 328 million people there are already some 400 million guns. In the first half of 2020 we added another 19 million. American criminals will never have any difficulty arming themselves. The GST-9 is a nifty hedge for the rest of us.
Think of the GST-9 like an amped-up GLOCK 19. The custom slide sports lightening cuts, scalloped gripping grooves and a rear deck with an RMR cut for a red dot. The frame can be several things.

The stippling and contours are what you’d pay extra for elsewhere. The frame is undercut for a high hold, and the dust cover is naturally railed for cool-guy stuff. The neatest bit, however, is the removable magwell funnel.

A pair of simple pushpins holds this rascal in place. The short version accepts 15-round GLOCK 19 magazines. The longer sort takes 17-round GLOCK 17 boxes. Both are flared for rapid reloads. Two minutes with a punch lets you choose between a G19 or G19X equivalent as the spirit leads.

The magazine release and slide stop are classic GLOCK and left-side-only. Holsters and accessories designed for the GLOCK interface seamlessly with the GST-9. The trigger is the standard combat-grade 5-lb. striker-fired sort we all adore. Frames come in black, OD green and FDE. Slides are available in black or FDE.

The slide comes preassembled and has all the
cool-guy stuff you’d pay extra for elsewhere.

The Trijicon RMR micro red dot sight drops right
into the slide without an adaptor plate.

Let Us Retire To The Workshop

Some gun build projects require enough support equipment to manufacture an operational spacecraft along with the technical knowledge to fly it. The GST-9 isn’t like that. The kit includes everything but the jig, bits and slide rails and will set you back $750. The $30 jig kit includes the other stuff. They have to put these components in separate boxes to placate the BATF.

I built two of these guns. For the first, I used the recommended basic power tools — a modest drill press and a Dremel tool. The second I finished out as though I was trapped on a deserted island with nothing but a proper toolbelt. This meant a hacksaw blade, a pair of wire cutters, a small round rasp, a coarse file, a spot of sandpaper and an unusual hand drill.

I once used this little drill to bore a hole in a man’s head. He had recently suffered a rather ghastly motor vehicle crash. The hole in his skull emergently relieved the pressure on his brain and restored his sunny disposition.

The hand drill that came as part of this burr hole craniotomy set was supposed to be disposable. However, I couldn’t bring myself to discard such an awesome trinket. I scrubbed it down, zipped it through the autoclave, and have used it for more than 20 years for minor household chores. Using this simple drill and those few hand tools I crafted what might be the world’s coolest polymer-framed handgun.

If you have access to a hobby-sized drill press the
pin holes are just about stupid-proof.

You can carve out most of the front semicircular piece with a Dremel
and a cutoff wheel or a hacksaw blade before dressing the rest up carefully.

This is what the frames look like before you finish sanding.

After sanding smooth, be sure to thoroughly clean the
interior of the frame to remove all polymer bits and dust.

Mechanical Details

The build has two major phases. The build kit from 80 Percent Arms includes both the requisite drill bits as well as the proper grinder attachment for your Dremel tool. Bolt the jig in place around the frame and then use your drill to bore the three pin holes.

These have to be perfect, but the jig keeps you honest. Each hole is drilled separately from each side, so it’s six different operations. However, this undertaking takes less time to do than to describe. A drill press helps keep things square and precise, but the manual drill and a steady hand produced an identical result.

You also need to remove four superfluous plastic tabs from the sides of the frame, as well as a little leftover material inside the front of the dust cover. Snip the tabs back carefully with wire cutters. This will leave a little jagged material left over that needs to be sanded flat. Remember, it is always easier to take stuff off than to put stuff back on.

On one frame I used the burr bit in my Dremel to flatten out the tabs. The other I finished out with a coarse file and a little elbow grease. Use some fine-grade sandpaper if you want a factory flawless result. The jig keeps things under control and shooting the gun smooths everything out over time.

Get the big chunks of the semicircular bit up front clear with a hacksaw blade or a cutoff wheel on a Dremel tool. Then dress the area with a round rasp or the Dremel grinder. Take your time, but none of this is hard.

The instructions are brief, thorough and clearly crafted by somebody who speaks English as a primary language. The company claims you can finish the frame in 15 minutes. Move with a purpose using power tools and you’ll be done in less than that.

Once you’ve completed the frame, it is assembly time. The slide assembly comes ready-to-run. The first GLOCK-style pistol you build might frustrate you some. The second will seem easy. 80 Percent Arms has a slick build video, but it was a bit short on detail. YouTube is awash in deeper versions. However, it’s tough to do it wrong. Building one of these guns from scratch makes one appreciate Gaston Glock’s genius.

With a little love, Will conjured this nifty little jewelry box out of a 100-year-old fencepost.

There’s always something special to a thing you built yourself. The GST-9
from 80 Percent Arms is a custom-grade defensive pistol you can build at home.

Will built two pistols and did a little mix and match for aesthetic purposes.

It’s tough to believe this cool, compact, effective defensive
pistol was actually a DIY home workshop project. At 12 meters
from a simple rest, the GST-9 shoots plenty straight.


I’m myself a lot like that cedar box. What folks see on the outside is rotten and nasty, suitable only to be thrown into the fire and burned. However, the Carpenter sees beyond the rot and filth. He sees potential. All that’s required is a little investment in effort and a spot of grace.

That simple box, this pistol and I all now have a higher, better purpose. We are each a synergistic combination of raw material and the Carpenter’s transformative skill. We’re all still flawed, but the end result is indeed redemptive.

Do it right and your GST-9 is everything a factory GLOCK 19 might be and more. Both of these guns shoot straight and well. It took me a couple magazines on the machine-finished version to get everything smoothed out, but both are now completely reliable.

I don’t want to seem like “That Guy,” but I like the fact I can build this gun at home without asking anybody’s permission or signing on to some government list. I don’t go in much for conspiracy theories myself, but I don’t trust politicians at all. Legally building a capable defensive handgun at home is the purest form of human liberty.

I accessorized one gun with a Trijicon RMR micro red dot and Streamlight TLR-8 G illuminator/laser sight and pegged the awesometer. This pistol fits my hand beautifully, while the lack of a serial number feels just a wee bit mysterious. I have no idea what the future might hold, but I guarantee our political opponents absolutely despise this thing. If you want your own handful of DIY freedom, I wouldn’t procrastinate.

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