Description
US Palm made its name on AK magazines and grips, so when the brand rolled out its first ground-up firearm at SHOT Show 2026, plenty of people took notice. The STORM CAT4 Pistol is the compact version of that debut, and it skips the usual entry-level shortcuts. Both the upper and lower receivers are machined from billet 7075-T6 aluminum with a Type III hardcoat anodized finish, and the upper gets a user-serviceable hardened steel case deflector and forward assist housing, the kind of detail that matters once round counts start climbing.
What Sets the STORM CAT4 Pistol Apart
The 11.5 inch barrel is cold hammer forged from 4150 chrome moly steel with a nitride finish and a 1:7 twist, so it stabilizes everything from 55 grain plinking loads up to 77 grain match ammo. The bolt and barrel extension both wear a DLC coating for smoother cycling and better corrosion resistance. Up front, US Palm's own Hurricane hybrid muzzle device uses a helical prong design to knock down flash and tame muzzle rise at the same time, which is a welcome touch on a short-barreled 5.56. The trigger is a genuine Hiperfire EDT Designated Marksman unit, a single-stage trigger with a crisp break that normally shows up as an aftermarket upgrade, not standard equipment.
Built for Either Hand, Ready for Accessories
Every control on the CAT4 is truly ambidextrous: safety, magazine release, bolt catch, and charging handle. Lefties get the same speed as everyone else, and righties gain options for awkward positions. The Mono-Loc handguard system locks into the upper receiver for serious rigidity, free-floats the barrel, and gives you a full-length Picatinny rail on top plus seven-sided M-LOK real estate for lights and lasers. A Magpul BTR brace and US Palm's reduced angle grip handle the ergonomics.
Running the CAT4 Pistol at the Range
At roughly six pounds with a 30+1 capacity and a flared magwell for quick reloads, this is an easy gun to move with. Add an optic to the rail, load up the included 30-round magazine, and it is ready to work for home defense, truck duty, or fast-paced range sessions.
Key Specifications
- Manufacturer: Century Arms / US Palm
- Model: STORM CAT4 Pistol
- MPN: HG00010001AAN
- UPC: 787450951501
- Caliber: 5.56 NATO / .223 Rem
- Action: Semi-Auto, Direct Impingement
- Barrel: 11.5" Cold Hammer Forged 4150 Chrome Moly, Nitride Finish
- Twist Rate: 1:7
- Muzzle Device: US Palm Hurricane Hybrid Flash Hider/Compensator
- Thread Pattern: 1/2"x28
- Receivers: Billet 7075-T6 Aluminum, Type III Hardcoat Anodized
- Trigger: Hiperfire EDT Designated Marksman
- Handguard: Mono-Loc Free-Float 7-Sided M-LOK with Full-Length Picatinny Rail
- Brace: Magpul BTR Adjustable
- Capacity: 30+1
- Weight: Approx. 6 lbs
What’s Included
- US Palm STORM CAT4 Pistol
- One 30-round magazine
Frequently Asked Questions
Does the STORM CAT4 Pistol come with sights?
No, it ships optic-ready with no iron sights installed. The full-length Picatinny rail running across the receiver and Mono-Loc handguard gives you plenty of room to mount a red dot, LPVO, or backup irons of your choice.
Is the US Palm STORM CAT4 fully ambidextrous?
Yes, and that is one of its biggest selling points. The safety selector, magazine release, bolt catch, and charging handle are all mirrored on both sides, so left-handed users can run the gun without workarounds and right-handed users get extra flexibility for reloads and malfunction clearing.
What kind of trigger does the CAT4 Pistol use?
It comes from the factory with a Hiperfire EDT Designated Marksman trigger, a single-stage design with a light, crisp break measured at roughly 3.25 pounds in published testing. That is a trigger most people buy separately as an upgrade, so getting it standard is a real value here.
Can I suppress the STORM CAT4 Pistol?
The barrel is threaded 1/2×28, the standard pattern for 5.56, so most common suppressors and muzzle devices will fit once you remove the Hurricane hybrid device. US Palm even makes a companion 5.56 suppressor designed to pair with the CAT4 platform.


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