Rock Island’s STK100: That’s So Metal

The Rock Island Armory / Armscor STK100 is a 9mm striker-fired pistol with a two-piece patent-pending aluminum frame that gives shooters a low bore axis and a 1911 grip angle. This is a serious full-size handgun with the stability you expect from a long sight radius and a 17 round magazine and an MSRP of $599.

Philippine based manufacturer Armscor is famous for its 1911 style pistols. They have won a place in the market as feature rich and high value. The innovative STK100 shows its 1911 heritage and the experience of an established arms company with a deep culture of quality.

I have several Rock Island Armory 1911’s. I have always liked them and found that they had a lot of custom features and good accuracy at a reasonable price. When I got the chance to shoot their new striker fired gun, the STK100, I jumped at it. I found it innovative and fun to shoot and I think you might like it too.


The solid aluminum frame gives STK100 heft for smoother shooting with reduced felt recoil. Since aluminum doesn’t flex like polymer, the STK100 promises improved accuracy potential.

The 1911 style ergonomics provide a great natural point of aim. The grip is grooved on the backstrap in a V-pattern and the front horizontally. The sides of the grip have very effective stippling. The undercut trigger guard enables a high grip on the gun in the modern fashion. All these features result in a solid grip for dynamic control.

The rails on the STK100 are long and offer substantial support for the slide.

The innovative (patent pending) clamshell frame design is made of two pieces joined by six bolts. The trigger parts are very familiar to Glock users, but where other guns use pins, the STK has screws to secure the parts. The dust cover has a section of Picatinny rail for mounting lights and lasers.

The frame-mounted rail readily mounts lights like this Streamlight TLR-8 G.

The grip surfaces provide a solid grip without being overly aggressive. The frame has a nice matte anodized finish which I find very appealing. The dust cover has extended rails. There is a captive recoil spring on a stainless steel rod.


The slide is a thing of beauty, machined from a billet of carbon steel. It features angled cocking serrations in front and rear. Seven lightning ports, (three on each side and one on the top) reduce slide mass which speeds up cycling for better reliability and potentially less muzzle flip.

The slide is a thing of beauty, machined from a billet of carbon steel with angled cocking serrations in front and rear.

The barrel measures 4.5”/114 mm, with conventional six-groove right-hand rifling and a 1:16 inch twist. This twist favors faster bullets like the 115 grain. Heavy and slow bullets may not stabilize. The barrel and slide do not interchange with Glock parts.

Ringing steel at 50 was a little tricky but quite possible. I hit about half of my shots.


The interchangeable front sight has a white dot. The fixed rear sight, mounted on the rear cover plate, is serrated and solid black. I found the STK100 shot about 3 inches low at 15 yards. The sight radius is 7.9”/201 mm. The STK100 can mount the sights already on the market designed for GLOCK pistols. When you remove the cover plate, you see that the slide is cut for direct mounting a Vortex optic.


As for the controls, the magazine release button is reversible, while the slide stop lever is on the left side only. The trigger is similar to other striker-fired guns, there is slack, a wall, and a break. My STK100 has a trigger break of about 5 pounds.

Assembly and Disassembly

Like other common striker-fired guns, to disassemble the STK100, you must de-cock it, then move the slide back a fraction of an inch while pulling down on the slide release levers.


The unloaded STK100 weighs in at 28.8 ozs, light enough for everyday carry. This is slightly more than the Glock 17 at 22.2 ozs but less than a full-size Sig 320 9mm at 29.5 ozs. The added weight mitigates the recoil impulse and provides a more stable platform for follow-up shots. Aluminum frames won’t flex like polymer frames so there is greater accuracy potential.


The weight and balance of the STK100 make it smooth shooting and easy to manage. There’s a little take-up as you engage the trigger safety, a wall, then a break at about 5 pounds. The reset is short.

Up close, the STK is fast and stable.
Plenty of accuracy for self-defense and practical uses.
The STK100 had acceptable accuracy with 115gr ammo out to 25 yards. These are 1/2 scale targets.

Holster Check

Even though the trigger guard looks big, the STK fit the Glock holsters I checked. Your experience may vary.

Ammo Compatibility

I had no problems with ammunition. I fired about 200 rounds through the STK100. One hundred rounds of ARMSCOR brass and 100 rounds of steel cased TULA, both 115 grain. I tried a few groups with 124 grain rounds and found that groups were noticeably larger.


The STK100 shipped with KCI USA 17 round magazines. My experience with KCI USA magazines has been very good and this was no exception. I also tried Glock OEM magazines and had two failures to extract but absolutely no problems after that.

The STK100 is a solid performer with some interesting features. I like the 1911 grip angle, beaver tail, and aluminum grip serrations. The weight, ergonomics, and low bore axis reduces felt recoil and enhances rapid target transitions. It is a full-size gun but still suitable for everyday carry while still being comfortable to carry all day. If you want a striker fired pistol with the heft and feel of the 1911, you have come to the right place.

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About the author: Mark Miller is a former Customs Agent and a Green Beret who served in Afghanistan and a number of other live fire locations. A student of firearms and shooting, he is an FFL and a SOT. The guiding philosophy of his life is that terrain and situation dictate tactics and the enemy always gets a vote on any plan.

{ 20 comments… add one }
  • Ej harbet August 28, 2021, 11:18 am

    Kind of want especially if under $400

  • YankeeDespot August 27, 2021, 10:56 am

    I reload many pistol calibers- except 9mm. Maybe ROck Island can make one in .40 or .45?
    No need to scold me. I know .40 is passé, but I started before many of you were born, and 9mm was not good then.
    They certainly know .45….

  • Chief August 24, 2021, 10:01 am

    So an aluminum framed Glock clone….

    • Mark Miller August 24, 2021, 7:12 pm

      Not so fast Chief, The STK100 striker fired, but it is not much like a glock. It may not be your cup of tea, but a full size hefty all-metal gun with a 1911 grip angle which uses common magazine has a certain appeal.

  • Michael Christensen August 23, 2021, 10:06 pm

    So what parts are interchangeable with Glock? Sounds like the trigger, sights, and magazines.

    • Mark Miller August 23, 2021, 11:29 pm

      Glock magazines work and it fits into the holsters I checked. The slide and barrel do not interchange.

  • tom mix August 23, 2021, 7:26 pm

    thought one of the benefits of polymer was that it reduced recoil by flexing

  • Brad August 23, 2021, 1:18 pm

    Good write up.

  • Treestand III August 23, 2021, 11:37 am

    Not bad …but my G-26 Gen 1.5 (Baby Glock) wt a 4″ Bbl shoots 15yd & 20yd just like STK100..tell me why should I change? be cause it’s newer and it’s 2.5Lb….My Glock is 17oz wt a 10 round mag, In Fla,you carry ITWB with a nice Hawaiian shirt Cargo Shorts & Flip-Flops. Happy Trails Y’all

    • Mark Miller August 23, 2021, 4:56 pm

      Not everyone can shoot the Glock 26 well. For your application, it sounds perfect. A full size all metal handgun is for people who shoot. Carry in the tropics is a different deal, I like my P365 and find it fits my hand better than a G-26. The STK100 is a whole different thing.

  • Dr. Strangelove August 23, 2021, 10:18 am

    Clamshell design? Sounds like they’re borrowing from Kel Tec. I’ve had two of their commanders in 10 mm and their 1911 in .22 mag works great.

    • Mark Miller August 23, 2021, 9:54 pm

      There is nothing new in firearms design. The first clamshell design I am aware of is the 1950 Danish Madesn M/50. Made of stamped sheet metal, the SMG was stamped from 2 pieces shaped with an integral rear pistol grip and magazine housing. The two pieces fit together like a clam shell with the hinge at the rear of the pistol grip. The firearm was held together with a barrel locking nut which is threaded onto the fore section of the two receiver halves. I am no expert, there are probably many others.
      Danish Madesn M-50 SMG

  • MagnumOpUS August 23, 2021, 9:14 am

    “…The unloaded STK100 weighs in at 28.8 ozs, …slightly more than the Glock 17 at 22.2 ozs …”

    Most folks wouldn’t describe this
    numerical or empirical difference as ‘slightly’.

    And thank you for your service to our Republic.

    • Mark Miller August 23, 2021, 10:10 am

      Thanks for the comment. I see the math you did there. The STK100 has a solid feel to it that many shooters will appreciate. The heft definitely helps when you are shooting. Weight for carry is different for different people. For me there is little difference.

  • Frank August 23, 2021, 9:10 am

    Err… that’s kind of a “bait and switch” title. Reading the title, one would think the article compared/contrasted this weapon with a glock… didn’t happen.

    Love ’em or hate ’em, glocks have survived several attempts to “unseat” them as one of the most popular weapons in use by military and police forces worldwide. I remember back when Sig claimed that they were going to “put Glock out of business” with their first polymer framed pistol. Thought it was rather interesting that their plans to do so hinged on imitating the very thing they sought to displace.

    • Mark Miller August 23, 2021, 10:13 am

      There is really not a comparison. The STK100 is all metal. It has a different grip angle and a very different feel. It is designed for a different shooter. If you like your glock, you can keep your glock. If you want an all metal striker fired gun with a 1911 grip angle, check out the STK100.

      • Frank August 23, 2021, 4:32 pm

        I agree there is no comparison, yet the email title from GA Digest reads:

        “Is the RI STK100 a Glock Killer?,… “

  • Godfrey Washington August 23, 2021, 8:59 am

    This seems like a good bet but I think Steyr has the best polymer frame out of the box pistol going.

    • Mark Miller August 23, 2021, 10:14 am

      The thing about the STK100, it is all metal with a heft and feel that is very different from polymer frame guns.

  • michel maranda August 23, 2021, 7:20 am

    Nice job Rock Island! Very interesting design.

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