U.S. Arms Co.’s origins can be traced back to 2016 with research-and-development efforts for military contracts, and the company came to market in 2019 with its M-905 Talon muzzle brake as a result. Since then, the catalog has been expanded to include a variety of AR-15-pattern rifles. In 2024, U.S. Arms Co. relaunched its rifle series, organizing it into three distinct lines—M4 UTAW, Pro and Gen II Champion.
Laying the foundation for the series is the baseline M4 UTAW reviewed here. The carbine is built around an upper and lower receiver pair machined from billet 7075-T6 aluminum and finished in a number of colors and camouflage patterns. Our test sample for this evaluation had been given a Flat Dark Earth Cerakote finish.
The flat-top upper receiver comes with an industry-standard 1913 Picatinny rail for optics and is outfitted with Strike Industries’ Latchless Charging Handle and polymer ejection port cover. The forward assist has been omitted from this rifle. In order to save weight, a pronounced recess has been cut into the lower receiver’s magazine well.
Outfit with an A2-style pistol grip, U.S. Arms Co.’s enlarged trigger guard, a Magpul MOE Carbine stock and a mil-spec safety selector, the lower receiver’s staked buffer tube has six positions and comes standard with an H1 buffer. Our test rifle featured a cassette-style, single-stage TriggerTech Duty trigger; in our testing, it released consistently at 5 lbs., 8 ozs., of pressure.
Perhaps the most unique feature of the lower is that it is designed to eliminate a perceived issue that has irked AR enthusiasts since the platform’s introduction in the 1950s—receiver rattle. Shooters have been using foam ear plugs, O-rings and a variety of other homebrew concoctions to tension their receiver sets. The industry has also answered this consumer desire with several products; UTG Receiver Wedges have been on the market for a number of years and many of the lowers offered by Springfield Armory, American Defense Mfg. and Radian Weapons include nylon-tipped tensioning screws to eliminate receiver wobble. Instead, U.S. Arms Co. introduced the Cam-Lock, which sets itself apart from the rest of the market by pulling the receivers together rather than just pressing up on the takedown pin lug, which actually just pushes the rear of the receivers apart.
(l.) Unlike many other companies’ efforts to address receiver rattle, U.S. Arms Co.’s patented Cam-Lock system actually pulls the upper and lower receivers together to reduce play between them rather than just pushing up on the takedown pin lug. (r.) The M4 UTAW comes from the factory with both a 15″ free-floating handguard and a mid-length, direct-impingement gas system.
The M4 UTAW rifle comes with a 15″ free-floating handguard machined from 6061 aluminum; it features a full-length Picatinny top rail and M-Lok slots at the 3-, 6- and 9-o’clock positions. There are trapezoidal cutouts on the diagonal flats for weight savings and heat dissipation. Two quick-detach sockets at the rear of the handguard allow for easy sling mounting in conjunction with the 1.25″ slots found on the six-position MOE Carbine stock.
At the heart of the carbine is a 16″ barrel chambered in 5.56 NATO constructed from chrome-moly-vanadium steel with a 1:7″ twist rate. The barrel is phosphate-treated and chrome-lined. It has a mid-length gas system that works in conjunction with a nickel-boron-treated bolt carrier with an MPI-tested bolt; choosing to use a mid-length system results in a softer recoil impulse and less parts wear compared to the carbine-length gas system seen on many M4-type rifles. The muzzle has 1/2×28 TPI threads to accept most common .223-cal. muzzle devices. This particular rifle comes with the Strike Industries Venom four-prong flash hider attached.
The U.S. Arms M4 UTAW comes with a one-m.o.a. guarantee when using match ammunition. When we set out to test the rifle’s accuracy potential using the American Rifleman protocol of shooting five consecutive, five-shot groups at 100 yards, we gathered three loads featuring different types of projectiles and headed to the range. We topped the rifle with a SIG Sauer Whiskey 5-25X riflescope and commenced fire from a bag-supported position; we were pleasantly satisfied with the results.
The rifle attained its 1-m.o.a. promise with two of the three loads tested, and nearly met it with the third as well. It delivered a 0.54″ group with Federal’s 77-grain Gold Medal match load and—more surprisingly—a 0.85″ group with SIG’s 55-grain FMJs. For all 15 groups fired through the rifle, it managed an average of 1.45″, which is quite serviceable for a carbine of this type. The firearm was perfectly reliable, with no malfunctions during the 200-round course of fire.
While representing its entry-level trim, which lacks the upgraded triggers, furniture, barrels and muzzle devices that the more deluxe Pro and Gen II Champion models offer, the U.S. Arms Co. M4 UTAW nonetheless does incorporate some of the company’s nicer features and innovations, a free-floating handguard and Cam-Lock lower, at a more attainable price point. As a result, it offers quality and accuracy in a lightweight carbine deserving of a place in any enthusiast’s collection.
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