Rost Martin's New RM1S: The Best Subcompact 9mm?

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Almost exactly one year ago, we introduced Shooting Times readers to the then-new Rost Martin Firearms Co. with our report on the compact polymer-frame, striker-fired Rost Martin RM1C 9mm semiautomatic pistol. Of course, it was the company’s first production pistol. Since then, Rost Martin has introduced the RM1C California Compliant and RM1C Comped versions. New for 2025, Rost Martin has a subcompact version, and it’s called the RM1S. Here’s what you need to know about the new pistol.

The Best Features

The new RM1S has a 3.6-inch barrel with 1:10 twist, and it comes with two magazines. A flush-fitting magazine holds 12 rounds of 9mm ammo, and an extended mag holds 15 rounds. The pistol is 4.4 inches tall, 1.12 inches wide, and 6.72 inches long. It weighs 19.76 ounces. The grip circumference is 5.25 inches. Just for comparison purposes, the earlier RM1C comes with 15- and 17-round magazines, and it is 4.92 inches tall, 1.23 inches wide, and 7.96 inches long. It weighs 21.1 ounces.

The RM1S’s steel slide has wide grasping grooves at the front and the rear. It has glare-reducing striations on top. And it is finished in matte black. The rear sight is dovetailed into the slide, and it has a U-shaped notch and fine horizontal striations. The front sight also is dovetailed into the slide. It has a single white dot, and it is angled to help facilitate a snag-free draw. By the way, the RM1S fits holsters for similar-size Glock pistols. The top of the slide is cut for installing a red-dot sight, and the pistol comes with one optic-mounting plate that fits the RMR footprint. Plates with other footprints are sold separately, and they can be ordered through the Rost Martin website.

The polymer frame has an integral accessory rail with two cross-slots. The only color offered at the time of this writing is black. The fact that the RM1C is offered in black, Flat Dark Earth, green, and stone gray colors may indicate that someday down the line perhaps the RM1S also will be offered in those options, but that’s not an official statement. It’s simply my personal prognostication. The RM1S’s frame has expanded textured areas on the grip and on both sides of the frame where the trigger finger can rest. Rost Martin calls the texturing pattern Responsive Grip Texture (RGT). It is a proprietary laser-stippled texture, and it is effective while not being too aggressive. The front of the trigger guard has horizontal ridges, and the back inside of the trigger guard has a molded-in trigger stop.

Like that of the RM1C, the backstrap of the RM1S’s grip frame can be switched between three different backstrap sizes. They also wear the RGT texturing. The company calls attention to the new RM1S’s beavertail at the top of the grip. It provides a higher handhold. There’s a hidden lanyard slot on the back side and bottom of the grip, and the bottom of the grip frame is flared for easier magazine insertion. Speaking of the magazines, the RM1S comes with two high-capacity magazines. The bodies are steel, the followers are synthetic, and the baseplates/bumper pads are synthetic. Like I mentioned at the beginning of this report, one magazine holds 12 rounds of 9mm ammo, and an extended mag holds 15 rounds. The backs of the magazines have numbered witness holes.

The pistol’s trigger has a flat face, and the mechanism incorporates a trigger safety lever similar to other striker-fired pistol designs. Our sample’s trigger pull averaged 6 pounds, 6 ounces, according to five measurements with an RCBS trigger pull gauge. It had some take-up, but it broke crisply and consistently. The back of the slide features a cocking indicator. When the pistol is cocked, a red dot is visible. Also, the top rear of the barrel’s chamber and the slide have a witness notch that allows a chambered round to be viewed. For anyone interested, the pistol will fire with the magazine ejected. And the pistol’s slide stop and magazine release are ambidextrous.

The RM1S disassembles much like other striker-fired pistols; however, the procedure does not require the trigger to be squeezed. By the way, with my jury-rigged setup, I measured the amount of force required to rack the RM1S’s slide, and it averaged 22 pounds. That’s right in line with other striker-fired pistols that I have measured in the past. Like I said earlier, the new-for-2025 RM1S is chambered for the 9mm Luger. I’ll remind readers that the 9mm Luger cartridge has been around for a very long time. It was originally developed by Georg Luger and introduced in 1903 for use in autoloading military pistols. It has served as a duty and defensive round for militaries, law enforcement agencies, and civilians around the globe.

Developments over the last several decades have established the round’s potential for effectiveness and accuracy. Typical choices for defensive purposes are 115-grain, 124-grain, 135-grain, 147-grain, and 150-grain expanding-type bullets. The loads I fired in those bullet weights (note that I did not shoot any 150-grain loads) in the new RM1S’s short 3.6-inch barrel produced velocities ranging from roughly 950 fps to more than 1,300 fps, with energies ranging from 291 ft-lbs to 443 ft-lbs. The 9mm Luger is undoubtedly the most popular handgun cartridge in the United States and has been for many years now. It is well suited for personal defense, match competition, and plinking. Heck, it also can be effective for hunting small game, too.

Subcompact Shootability

I put the RM1S through a thorough shooting evaluation by firing three, five-shot groups from a benchrest at 25 yards with a dozen 9mm factory loads. The results of all that shooting are listed in the accompanying chart. The loads ranged from the Black Hills 100-grain HoneyBadger +P to the Browning, SIG SAUER, and Winchester 147-grain loads, with 115-grain, 124-grain, and 135-grain offerings from Black Hills, Federal American Eagle, Hornady, Nosler, Remington, SIG SAUER, Speer, and Winchester in between.

As you can see, all loads averaged 3.75 inches or less, which is well under the old self-defense standard of 4.25 inches at 25 yards. Overall average accuracy was 2.96 inches, and at 2.00 inches, my best average came with Nosler Match Grade 124-grain JHP ammo. That load’s average velocity was 1,104 fps from the pistol’s 3.6-inch barrel measured 12 feet from the gun’s muzzle with a Competition Electronics ProChrono Digital chronograph.

My second-best average accuracy was achieved with SIG SAUER 115-grain JHP ammunition. The three-group average for it was 2.25 inches. That load produced an average velocity of 1,222 fps. The third-best average accuracy came with Black Hills 100-grain HoneyBadger +P ammo. The three-group average for that was 2.50 inches, and the average velocity was 1,164 fps.

Three loads tied for fourth place, and they averaged 2.75 inches for their three, five-shot groups at 25 yards. They were the American Eagle Syntech 115-grain TSJ, the Black Hills 124-grain JHP, and the Hornady Critical Duty 135-grain FlexLock loads. Their average velocities were 1,110, 1,092, and 1,122 fps, respectively. Rounding out the top five in terms of accuracy was the SIG SAUER 147-grain FMJ ammo. Its average velocity was 1,013 fps, and its group average was 3.00 inches.

Function was 100 percent throughout my entire shooting session. Muzzle jump and recoil were easy to manage. And the pistol was very comfortable to shoot. While the RM1S’s grip frame is noticeably shorter than that of the RM1C, three fingers of my shooting hand fit easily and comfortably, without needing to drop the little finger under the magazine. And for the record, I wear medium-size gloves. I like the new RM1S a lot. You can’t beat its feature set. You can’t beat its 100 percent functionality. And you can’t beat its retail price of just $469.

RM1S SPECS

• MANUFACTURER: Rost Martin, rostmartin.com
• TYPE: Striker-fired autoloader
• CALIBER: 9mm Luger
• MAGAZINE CAPACITY: 12 and 15 rounds
• BARREL: 3.6 in.
• OVERALL LENGTH: 6.72 in.
• WIDTH: 1.12 in.
• HEIGHT: 4.4 in.
• WEIGHT, EMPTY: 19.76 oz.
• GRIPS: Integral to polymer frame
• FINISH: Black Tenifer slide, black frame
• SIGHTS: Black U-notch rear, white-dot front, optic ready, RMR foot-print plate included
• TRIGGER: 6.35-lb. pull (as tested)
• SAFETY: Trigger safety lever
• MSRP: $469

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