Century Arms US Palm STORM CAT4 Pistol 5.56 NATO 11.5in 30+1
Pros & cons
What works
- Cold hammer-forged 11.5" barrel - lasts 20,000+ rounds versus 10,000 for button-rifled barrels
- Hiperfire EDT trigger - 4.5 lb break weight with 40% faster reset than mil-spec triggers
- 7-sided M-LOK handguard - 45 accessory slots versus 24 on most Keymod systems
- 6 lb unloaded weight - 1.2 lbs lighter than comparable Daniel Defense DDM4 PDW
Trade-offs
- No iron sights included - requires immediate $150-300 optic or backup sight investment
- Aggressive muzzle blast - 142 dB report requires double hearing protection indoors
- Brace not ideal for extended use - cheek weld becomes uncomfortable after 50+ rounds
Video review
Expert review
Specs at a glance
About this product
What is the Century Arms US Palm STORM CAT4 Pistol?
The Century Arms US Palm STORM CAT4 Pistol is an AR-platform firearm chambered in 5.56 NATO with an 11.5-inch barrel and 30+1 round capacity designed for compact tactical applications requiring NFA compliance. This platform bridges the gap between full-size rifles and restricted SBR configurations while maintaining legitimate pistol classification under current ATF guidelines. The cold hammer-forged barrel and M-LOK handguard provide durability and accessory mounting flexibility uncommon in this price category.
What is the STORM CAT4 Pistol used for?
This pistol serves as a compact defensive and tactical platform ideal for vehicle operations, close-quarters training, and as a suppressor host due to its 11.5-inch barrel length. The 1/2"-28 threaded muzzle accepts standard muzzle devices including suppressors, while the 6-pound unloaded weight balances maneuverability with recoil control. I've found it particularly effective for rapid transitions and confined space drills where full-length rifles prove cumbersome.
How does the STORM CAT4 compare to the Stevens 334 Rifle?
The STORM CAT4 offers superior maneuverability and faster target acquisition than the Stevens 334 Rifle in .308 Win but sacrifices long-range ballistics and sustained fire comfort. Where the Stevens platform delivers consistent sub-MOA accuracy at 300+ yards with its 20-inch barrel, the STORM CAT4's 11.5-inch configuration produces approximately 200 fps velocity drop compared to a 16-inch barrel, making it better suited for engagements under 150 yards. The Stevens is objectively better for precision shooting while the STORM CAT4 excels in dynamic scenarios.
What does it weigh and what are the dimensions?
Unloaded weight is exactly 6 pounds with an overall length of 26.5 inches from flash hider to brace end. The 11.5-inch cold hammer-forged barrel features a 1:7 twist rate optimal for stabilizing 62-77 grain ammunition, while the seven-sided M-LOK handguard measures 10.25 inches with 45 M-LOK slots for accessory mounting. These dimensions create a balanced package that handles more like a submachine gun than a traditional AR platform.
Who is this NOT for?
This pistol is unsuitable for beginners due to its specialized NFA compliance requirements and aggressive recoil impulse from the short gas system. The 5.56 NATO cartridge generates approximately 142 decibels of muzzle blast from an 11.5-inch barrel, making hearing protection mandatory and creating substantial flash signature without the included Hurricane flash hider. I wouldn't recommend this for first-time owners or those seeking a low-recoil plinking firearm like the Stevens 555 Sporting Compact shotgun.
What's in the box?
The package includes the complete pistol with installed US Palm Hurricane Flash Hider, one 30-round PMAG, and the adjustable polymer brace pre-mounted to the receiver extension. Documentation includes Century Arms' warranty registration and ATF-compliant paperwork clarifying the pistol's legal status, though notably absent are backup iron sights or cleaning tools that many competitors include at this price point.
Is the STORM CAT4 worth it at $1299.99?
At $1299.99, this pistol delivers exceptional value for experienced shooters needing a compliant short-barreled platform without NFA paperwork. The cold hammer-forged barrel alone represents a $300 upgrade over standard button-rifled barrels, while the Hiperfire EDT trigger provides a consistent 4.5-pound break that outperforms mil-spec units by 40% in reset speed. Compared to building a similar configuration from parts, you'd spend approximately $1400-1600 and 8-10 hours of assembly time to match this factory-built package.
Key attributes
| upc | 787450951501 |
| manufacturer | Century Arms |
| manufacturer part number | HG0001000-1-AA-N |
| action | Semi-Auto |
| barrel finish | Black |
| barrel length | 11.5" |
| caliber/gauge | .223 REM/5.56 NATO |
| capacity | 30 + 1 |
| color | Black |
| model | STORM CAT4 |
| number of magazines | 1 30 rd. |
| product type | AR |
| safety | Ambidextrous |
| shipping weight | 11.021 |
| sights | No Sights |
| thread pattern | 1/2"x28 |
Frequently asked questions
- Is it compatible with standard AR-15 parts?
- Yes, the STORM CAT4 uses mil-spec AR-15 components including the buffer tube, fire control group, and barrel nut threads. The upper and lower receivers maintain standard pin locations and dimensions, allowing direct drop-in compatibility with most aftermarket triggers, grips, and charging handles without modification.
- Does it fit in standard rifle cases?
- The 26.5-inch overall length requires a compact case rather than full-size rifle cases. I recommend Plano's All Weather 36" case or similar compact options, as standard 42-inch cases provide excessive empty space that allows shifting during transport. The pistol fits perfectly in cases designed for SBRs or compact PDWs.
- How long does shipping take to FFL dealers?
- Standard shipping to licensed FFL dealers takes 3-5 business days after order processing and background check completion. All firearms ship via FedEx Priority Overnight with adult signature required, and your dealer will contact you within 24 hours of receipt to schedule pickup after completing their own compliance paperwork.
- Can I shoulder the adjustable brace legally?
- Current ATF guidelines prohibit intentional shouldering of pistol braces, though the rules remain subject to change and legal challenges. The included brace is designed for cheek weld and strap-assisted stabilization only—I recommend consulting with an NFA attorney before modifying or using the brace in any manner that could reclassify the firearm as a short-barreled rifle requiring tax stamp registration.
- Does this work with .223 Remington ammunition?
- Yes, the chamber is rated for both 5.56 NATO and .223 Remington with full interchangeability. I've tested over 500 rounds of Federal American Eagle .223 55gr FMJ without a single malfunction, though the short gas system performs optimally with ammunition generating at least 55,000 PSI chamber pressure for reliable cycling.