Gun Review: 80% Arms GST-9 Pistol Build Kit

80% Arms' GST-9 is a high-performance handgun and a fun build.

by Lee Williams

Americans have been making guns in their homes since before there was a United States of America — but not this American.

My gun-building history was nonexistent. I’ve replaced some furniture and muzzle devices on a few AKs, but that’s about it. So, when David from 80% Arms called and said he wanted to send me a pistol build kit to review, I thought he’d called the wrong number. I told him I’d never built any firearms and knew nothing about the process.

“Then you’re perfect,” he said. “Give it a try. You might enjoy it.”

A few days later the GST-9 pistol kit arrived in the mail — in the mail. There’s something almost nostalgic about getting a gun — albeit an unassembled kit and not a legal firearm – shipped directly to your home.

Due to ATF regulations, the router jig and frame rails were shipped separate from the GST-9 frame. ATF’s rules currently require the end user to purchase one jig for every frame they build, and the pistol’s frame rails are only included with the jig. Like everything the ATF does, the rule makes absolutely no sense. However, this will change soon with the release of the GST-9 Infinity jig, which will include multiple rail pack options.

I should point out that a federal court in Texas issued an injunction against the ATF, which allows 80% Arms to continue operating unabated. The company posted a Q&A page on their website that answers all of the questions I had about the ATF’s infringements on their civil rights and business practices. They also established a legal defense fund, because the federal shenanigans are never ending. Whether you buy a kit or not, please take a look at their legal defense fund. After all, they’re fighting for all of us.

Established in 2013, 80% Arms is the leading 80% manufacturer in the country. In my opinion, they produce incredibly reliable and effective components for the home builder. For example, they created the first 80% router jig which revolutionized the home building process because it allows anyone from experienced engineers to first time users like me to successfully and quickly mill out an 80% lower using common household tools.

Originally based in Garden Grove, California, the company moved to a new and much larger location in Fort Worth, Texas, due to an influx of anti-gun legislation in California. They just soft-launched a new showroom at their Fort Worth store.

In addition to the GST-9 they sent me, the company sells jigs, tooling for the jigs, their own router jigs designed specifically for milling 80% lowers, 80% AR-15, AR-9 and AR-10 lowers, uppers and a ton of parts and accessories.

Preparation

I read nearly every instruction manual and customer review on the 80% Arms website, and there are a bunch, to get ready for the build. The tools I needed were minimal. A hand drill would have sufficed, but a drill press is recommended, so I bought a table-top drill press off of Amazon for around $50.

You should also have a Glock punch, a mallet and some fine-grit sandpaper. If you’ve never fully disassembled a Glock or installed a lower parts kit — I hadn’t — there are numerous videos on YouTube that will walk you through the process. I’d recommend watching them several times.

Components

My build kit came with a polymer jig, a MOD1 frame and the Wraith slide.

The frame secures rigidly inside the jig with just screws and nuts. There’s no movement at all. It’s locked, and I’m told that 80%’s new metal Infinity jig is even better, because it’s durable, reusable and made of 6061 billet aluminum — the same material as some of their lowers. The new metal jig is “backwards compatible,” so it will work with V1 and MOD1 frames, while producing consistent results every time. The GST-9 Infinity Jig and its rail packs will be available for purchase beginning Friday, March 24^th.

Polymer jig, rails, drill bits and pins. (Photo courtesy 80% Arms.)

The first thing I noticed was the aggressive stippling on the “gas pedals,” located on both sides of the frame, spaced perfectly for your weak-side thumb.

The rear rail is now a two-piece design, which prevents builders from accidentally bending the rail while hammering in the retaining pin.

The frame came with two different grip modules, that can be switched out by removing two pins. The smaller module will accept G19 magazines, and the larger module takes G17-size mags. In my humble opinion, this was a genius design feature.

The Wraith slide features lightening cuts, forward serrations and “Dragon Scaling” on top. (Photo courtesy 80% Arms.)

The Wraith slide came fully assembled, and it is a far cry from a standard G19 or G19 clone, which is why some call the GST-9 the “Gucci Glock.”

The match barrel is fluted. The slide has forward serrations on the sides and “Dragon scaling” on the top, which makes press-checks easier. The slide has lightning cuts to reduce recoil. However, the best feature is that it comes optics ready with an RMR cut, which also accepts Holosun and other brands of sights.

All the edges are well beveled, so there’s nothing to snag or catch on clothing during draw strokes.

The build

The build was easy — a far cry from what I expected — and fun.

Once the frame was secured inside the jig, I drilled out the three holes on each side of the frame, rather than drilling all the way through the frame from one side, which is not recommended.

Five plastic tabs can be removed easily with the cutting tool drill bit, which is supplied with the kit. (Photo courtesy 80% Arms.)

Once drilled, I switched to the “cutting tool” drill bit, which is included, to grind off the four top tabs and one front tab — extra plastic, which I assume was left over from the molding process.

Some builders use a scalpel or a sharp knife to cut off the tabs, but the plastic seemed a bit too thick to cut it off. I was somewhat worried about grinding off too much material, but the jig prevented this from happening.

Once the plastic was removed, I popped the frame out of the jig and sanded the areas where the tabs were until they matched the frame.

After I was satisfied, all that was left was to was to insert the lower parts kit into the frame. I’d like to say I did it right the first time, but after installing the parts kit and slide, I noticed the connector was still sitting on my work bench. The slide of course wouldn’t come off, so I used a lifeline and called a Glock armorer friend who talked me through fixing my mistake.

After some cursing, I had a completed pistol.

Total build time was around four hours.

Range report

80% Arms claims their handguns need a few hundred rounds and plenty of lube before they’re broken in. They recommend firing 50 rounds, swabbing the gun down with lube, firing another 50 rounds, adding more lube, and so on.

I lubed mine normally, loaded four mags with Igman 124 gr FMJs and fired them all off without a single malfunction. It was exactly like shooting an OEM handgun straight out of the box. Three-hundred rounds later, I still had zero malfunctions. The “gas pedals” proved to be an added bonus.

After dialing in my optic, accuracy was better than any Glock I’ve shot before, although I’ve never shot a Glock with a match barrel.

The GST-9 is accurate and reliable. I was able to keep controlled-pairs and controlled-threes inside three-inch dots at seven yards very easily, which is about all I can ask of an EDC handgun. About half the time the groups were one ragged hole.

Takeaways

The MSRP for the kit I received is $749, although there are cheaper kits available that don’t come with the tricked-out slide. Note: 80% Arms build kits sellout quickly, so check their website for availability.

I wasn’t ready for the reliability. This is a carry gun, and I will add it to my EDC and backup guns.

The 80% Arms GST-9 is reliable and accurate, and takes its place with the author’s EDC and backup guns.

The good folks at 80% Arms are on the frontlines of Joe Biden’s war on our guns. That alone is reason enough to give them our support. But as promised, the build process was fun and highly addictive. I just received my second build kit, which will be built with the new metal GST-9 Infinity jig.

Bottom line: If you’re looking for a fun build and a dependable and accurate handgun, look no further than 80% Arms, but keep in mind, you won’t be able to stop at just one.