Firearms

First Look: Rock Island Armory STK100 9mm

Rock Island STK100 pistol resting on the rusty pipe rail of a fence

Rock Island Armory (RIA), with factories in the Philippines and a stateside business center in Pahrump, Nevada, shook up the striker-fired world with its 2021 release of the STK100. This gun is different, in numerous ways.

What’s most striking about this gun — out of the box — is its weight. Sure, it’s a full-size 9mm that uses 17-round, Glock-compatible magazines. However, this gun is noticeably heavier than the average full-size pistol because its frame is aluminum, not polymer.

Rear sight and optic mounting plate on the RIA STK100
The plate holding the rear sight is removable to allow mounting an optic. Currently, the only optic plate available is for the JPoint red dot.

RIA STK100 Features

RIA is known to make a smart 1911 on an aluminum frame, and used its manufacturing experience to make what is — to my knowledge — the industry’s first aluminum striker gun. The specs say it weighs 1.8 pounds, but it feels like more in the hand.

Following what seems to be a trend among gunmakers for ’21, the STK100 bears a long, ported slide over a 4.5-inch barrel, and is marketed as a competition firearm. While I and others would be happy to shoot this gun in competition, a lack of custom holsters will surely limit its exposure on the match scene.

Despite that shortcoming as of the date of this writing, so much is done right with this gun. Ergonomically, pistols don’t get much better. The controls mimic a Gen 5 Glock, with a prominent slide catch that’s in easy reach of most thumbs. Where the mimicry stops is in the lack of an ambi-friendly design. The controls are on the left of the frame, period.

Fine ergonomics are built into the molded grip, which is unusually skeletonized with channels that serve as both traction and decoration. A beavertail protects the meaty-handed shooter from slide bite. The trigger guard adds a bit of a throwback, or as I like to call it, steampunk feel to the gun with its classic 1911 profile.

The black anodized finish is consistently matte in appearance, but there’s an unexpected shiny, polished end cap on the recoil spring guide rod when viewed from the front. Despite these old-school features, RIA included an accessory rail, mixing the artful touch of old with practical new features.

closeup of the STK100 grip
The unique, aggressive grip texturing gives the STK100 a distinctive look.

Operation and Handling

The most important and enjoyable aspect of this gun’s handling is in the recoil. It’s the flattest-shooting 9mm I’ve experienced. RIA nailed several key features including the large lightening cuts on the left, right, and top of the slide, plus the heft of the STK100. This combo makes for reliable and easy shooting.

I ran numerous brands and bullet weights of FMJ and a bit of Federal HST through it, including mixing ammo brands in the same mag. It did not matter. The STK100 ran them all without a failure to feed, fire, or eject.

The pistol is equipped with iron sights. The front sight is a single white, non-luminous dot, staked from inside the slide. On the rear, a textured, plain rear sight is integral to the optic-mounting plate, so it’s sacrificed when a red dot is installed. The rear sight is not adjustable.

Lightening cuts on the top of the pistol slide
Both the top of the slide and sides of the slide feature lightening cuts that reduce weight to make the pistol easier to carry for long periods. On the range, you’ll also enjoy the reduced muzzle flip for faster follow-up shots.

Accuracy

RIA has set these sights nicely from the factory, though, and the gun is remarkably accurate. The day I unboxed it at the range, the day was without wind, so as a sort of joke I aimed my first shot with this gun at a steel silhouette 175 yards downrange. To my surprise, it hit from a logical top-edge hold.

The sights continued to do their part to help me make centered, accurate shots at closer ranges. RIA got this aspect right. There is a little more daylight on each side of the front sight than I prefer, but for combat/competition purposes that can be preferable.

Specifications

Rock Island Armory STK 100
Caliber:
 9mm
Capacity: 17, two magazines included
Barrel: 4.5 inches
Overall length: 7.01 inches
Overall width: 1.25 inches
Overall height: 5.16 inches
Overall height: 5.16 inches
Weight: 1.8 pounds unloaded
Front sight: Tenon cut with retaining screw
Rear sight:  Fixed, integrated, on optic cover plate
Grips: Aluminum (integrated on frame)
Finish: Black anodized
Trigger pull: 3.0-7.0 pounds

Speaking of red dot mounting, the STK100 is made to accommodate the $300 JPoint red dot. No word on whether other mounting patterns will be offered in the future.

The trigger has the familiar block safety common to modern striker guns. There is a striker and drop safety built into the STK100’s internals also. There is no manual safety.

The trigger has a relatively short uptake and very palpable and audible reset. The break on my test model happened at 6.2 pounds on average. It had a bit of a metallic feel when dry firing. I didn’t perceive that same reverb using live fire. The trigger’s operation is suited to put the STK100 up against any high-quality, striker-fired semi-auto on the market.

Disassembly is a virtual clone of the Glock process, which is to say once a body knows how to manipulate the takedown button, it’s simple and fast. The slide racks a little stiff but with good technique, most shooters will not find it problematic.

Eve Flannigan shooting the Rock Island STK100
On the rage, the author found the STK100 to be a flat-shooting, enjoyable handgun.

Conclusion: Rock Island STK100

For anyone who wants a range gun or car/bedside security gun that’s a pleasure to shoot and stores plenty of ammo, the STK100 is a great choice. It’s made to run reliably. For those who’ve been dragged kicking and screaming into the era of “shootable Tupperware” or are still resisting the transition away from hammer-fired platforms, it offers a way to enjoy a sturdy metal-frame pistol.

Since its KCI magazines are interchangeable with Glock 17 mags, there’ll be no shortage or excessive expense to secure extra magazines. If some holster companies stand up and deliver products to fit this gun, it can indeed be a serious contender as a stock match gun.

The RIA STK100 breaks the mold by ditching the polymer and opting for an aluminum frame instead. It’s a bold move, but only the buyer will have the ultimate vote in whether RIA made a smart choice. Will you stick with polymer-framed guns or give the STK100 the nod? Share your answer in the comment section.

  • Glock 17 compatible KCI 9mm magazine
  • Lightening cuts on the top of the pistol slide
  • Rock Island STK100 pistol resting on the rusty pipe rail of a fence
  • RIA STK100 resting on a wooden stump at the edge of a green farm field
  • Rear sight and optic mounting plate on the RIA STK100
  • side lightening cuts on the slide of the RIA STK100
  • Eve Flannigan shooting the Rock Island STK100
  • closeup of the STK100 grip
The Mission of Cheaper Than Dirt!'s blog, The Shooter's Log, is to provide information—not opinions—to our customers and the shooting community. We want you, our readers, to be able to make informed decisions. The information provided here does not represent the views of Cheaper Than Dirt!

Comments (8)

  1. I have read quite a bit about this pistol, and I’m fairly impressed. The prices I have seen on Gunbroker will make this a player. I love aluminum frames, and I would come closer to buying this one over a Tupperware gun. Also, I have 3 Rock Island 1911s and they are excellent. A lot of gun for the money. The 1911s and a couple of CZ75 clones are the only autos I own, so I like all-metal hammer guns. If it had a hammer, I would definitely buy one.

  2. With the plethora of 9 mm polymer handguns ever expanding especially in more compact sizes it seems strange to me why they chose this particular larger size to come into the market ?! You didn’t mention where it sits price wise but I’m pretty sure they probably are coming in competitively even being what I feel is a better aluminum frame versus polymer which works fine in most situations. Also what does it come with in what type of package?

  3. I have RIA 1911s in both .45ACP & 9mm full sized and find them to be great operators. I also have Glocks in model 24 in 40cal, 22 in 40cal/9mm(changeable barrels) and 19X in 9mm just to say I have the plastic units. A Sig 229 which came as a 40 cal and has 9mm & 357sig barrels for play, a PX4 in 40cal and S&W 915 in 9mm. The Glock’s grip angle poses a problem for my trigger finger which the 1911s do not. I ware XL gloves. So, I have a variety and across the board mixture of hammered and striker fired designs and have to say I prefer hammers. And I prefer the metal frames, so my favorites are the RIA 1911s.

  4. All of the new firearms coming out is great, but maybe the gunmakers would do well to worry about the lack of ammunition and come together to improve that condition before there is no longer any use for their product.

    1. SIG is making a strong effort at producing its own ammunition and keeping the price down. ~Dave

  5. Im in. Will definitely buy this gun. Plastic and guns do not mix well. Ever watched a plastic frame or receiver flex when someone shoots?

    Plastic frames will break over time, plus they sre simply ugly.

    An all metal high cap striker fired pistol. Old idea reborn. Thank you RIA!

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