July 13, 2022
By Keith Wood
The firearms world is constantly evolving, each company looking for an advantage. This competition among manufacturers is good for us as consumers, because it drives innovation. For several decades, evolution has made guns smaller and lighter, largely relying on composite materials to get there. With the variety of polymer-framed, striker-fired pistols on the market, one company decided to go in a different direction.
Rock Island Armory’s STK100 is the company’s first striker-fired handgun, and this Philippines-manufactured handgun has a twist. The frame is machined from aluminum rather than molded from polymer. It is a new take on a modern design. As Rock Island Armory puts it, it gives the advantage of metal at the price of polymer.
Rock Island Armory is a division of Armscor Global Defense, Inc. Armscor is based in the Philippines, where its modern, CNC-equipped and ISO 9001-certified facilities produce both firearms and ammunition, mainly for global export. To give you an idea of the company’s scale, it produces more than 110 million rounds of ammunition per year in addition to hundreds of thousands of firearms. Armscor and its predecessors have been around for more than a century and have operated stateside since 1985. The firm is well known for producing 1911s for the budget-minded customer.
In a world where everything is becoming increasingly lighter, why would anyone want a gun that is heavier than it needs to be? The answer is physics. Lightweight guns are great to carry, especially concealed, but the shooter pays a price in terms of increased recoil and muzzle flip. On a carry gun, this is a worthy trade-off, but for home defense, competition, recreational shooting or even a duty gun, lighter is not always better.
Heavier is relative. The STK100 is roughly three ounces heavier than an unloaded Gen5 Glock 17, so the difference in mass is somewhat minimal. What does matter is that the weight is shifted downward into the aluminum frame, where it can best dampen recoil. Internally, the STK100 borrows a great deal from the proven Glock design, and it’s worth noting that many of the available aftermarket parts designed to work with the Glock 17 are compatible with the STK100.
The biggest differences between the two guns, other than the sticker price, are the composition and design of the frame. The STK100’s frame is made in two separate pieces, machined from aluminum billets that connect like a clamshell. Producing the frame in this manner cuts costs significantly, keeping the price down. The two frame halves are attached via six bolts that are visible on the right side of the frame running from the heel of the grip to the dust cover. I can’t recall ever seeing a similar arrangement on a handgun, but the system appears to work. The frame is anodized black and shows a slightly smoother satin finish than the matte slide.
Though the STK100 uses magazines compatible with the Glock 17, there are some differences in the frame’s external dimensions. No doubt due to the aluminum construction, the STK100 departs from the traditional Glock grip angle in favor of something more akin to a 1911. This is a subjective opinion, but I liked the vertical feel. Four panels are machined into each side of the grip in a pattern reminiscent of the Simonich Gunner pattern found on some 1911s. The frontstrap is cut with horizontal slots, and the backstrap uses angled cuts. Overall, the grip surfaces are not super-aggressive, which, like anything, is a trade-off. The frame’s beavertail is extended to prevent the slide from biting the hand.
A steel chassis sits inside the frame at the midpoint of the pistol, providing a solid surface on which the slide can ride. The combination of this steel and the surrounding aluminum has the effect of making the frame more rigid than polymer designs, which means it flexes less during recoil. In theory, this could lead to an increase in accuracy, although I didn’t notice a difference. A Picatinny-style rail is milled into the frame’s dustcover to facilitate the mounting of accessories such as lights or lasers.
There is no manual safety on the STK100. Like many modern handguns, the system relies on passive safeties, including a firing pin block and a lever in the trigger. The trigger blade on my test gun was aluminum rather than polymer and broke at 5.25 pounds with a bit of creep. The reset was short and tactile, and the trigger pull on the gun was one of its most attractive virtues.
The magazine release is not reversible but is extended just enough to allow for its use without shifting the grip. The slide stop has a small, rounded tab at the rear, which gives the thumb additional purchase without being cumbersome. A takedown lever on either slide of the frame rounds out the controls. The slide is machined from a block of carbon steel and wears a parkerized finish. While the aluminum frame is designed to add weight, the slide is made in such a way as to cut mass. The mass of a reciprocating slide can be a major force in the recoil impulse of a handgun. Reducing the weight of that component can reduce recoil, if imperceptibly. To this end, a long and narrow side cut is machined into the top of the slide along with three additional cuts on both the left and right sides.
STK100 Optics Ready
The iron sights on the STK100 are fixed. A steel front sight with a white bead is attached to the slide using a hex screw that runs upward from inside the slide. The rear is a simple, low-profile steel sight with a square notch and a serrated surface. The rear sight is removable, but only to accommodate an optic, not a replacement rear sight. Yes, the STK100 is an optics-ready handgun. The top of the slide is milled so that a red-dot sight with the Docter/Noblex footprint can be directly mounted without needing an adaptor. Sights that share that footprint include, among others, the Vortex Venom, Burris FastFire and Sightmark Mini Shot. I didn’t have such an optic available for testing, so I shot the STK100 with irons alone. It’s worth noting the rear sight must be removed to facilitate mounting an optic, so there is no iron sight picture to co-witness with the dot.
The barrel uses an integral ramp and locks into battery both at the lower lug and at the rear hood. The bore uses traditional rifling with six grooves and a 1:16 inch right-hand twist. Out of curiosity, I installed a Glock factory barrel on the STK100, and it was a drop-in fit, so most aftermarket barrels intended for that model should function in this handgun. Interestingly, the STK100’s barrel would not lock up properly in my Glock, so its hood dimensions are slightly larger.
The extractor is external, tensioned by a coil spring inside the slide. The ejector is fixed and rides on the frame. The recoil spring is a flat wire, and the guide rod is made from stainless steel. The spring is held captive by a hex screw at the front of the guide rod, which can be removed for cleaning or to replace the spring. Flat-wire springs have an extremely long life in my experience.
I fired three loads in the STK100 to test its accuracy and reliability. Accuracy was somewhat average for a handgun in this category, and reliability was 100 percent with each of the loads. The added weight of the aluminum grip no doubt made the STK100 a softer-shooting handgun, and it was very controllable.
As mentioned, the STK100 uses Glock 17-compatible magazines, and two 17-round Korean-made mags from KCI USA were included. The STK100 ships in a hard-sided plastic case. All Rock Island Armory firearms come with a limited lifetime warranty, and there are U.S.-based facilities available should that warranty become necessary. Refinishing the handgun, adding aftermarket parts or shooting handloads will void the warranty.
Most users won’t choose the STK100 for concealed carry due to its size and weight. It is not designed to fill that niche. According to NSSF, the events of 2020 created 8.4 million new gun owners in the United States. More than half of those individuals bought handguns, and retailers reported that the majority of buyers were motivated by a desire for self-protection. Still, that doesn’t mean they are all concealed-carry guns. A sizeable portion of those new gun owners are unlikely to carry their handguns outside of their home or vehicle. That fact creates a large market for handguns that are larger and heavier and aremmore forgiving to shoot than those designed for everyday carry. The STK100 fills that role well.
Striker-fired handguns offer many virtues and are here to stay. The same can be said for polymer frames, though they aren’t necessarily ideal for every purpose. For those looking for the benefits of a striker-fired handgun with the addition of all-metal construction, the STK100 is one of only a few guns that will get you there. That this metal construction comes at the retail price of a polymer-framed gun is icing on the cake.
Rock Island Armory STK100 Specs
Type: Striker-fired, semiautomatic
Capacity: 17+1 rds.
Barrel: 4.5 in.
OAL/Height/Width: 7.9/5.2/1.25 in.
Weight: 28.8 oz.
Construction: Aluminum frame with steel insert, carbon steel slide
Grips: Aluminum, integral
Sights: White dot front, fixed rear, optics ready
Safeties: Firing pin block, trigger lever
Trigger: 5.25 lbs. (tested)
Manufacturer: Rock Island Armory, armscor.com