Review: Kel-Tec RDB-C 5.56 Nato
July 25, 2018
Kel-Tec's RDB-C is a modern, state-compliant take on the traditional bullpup concept. Since its inception, the bullpup category has been described with having a pistol grip mounted ahead of the magazine, which allows engineers to design a very compact firearm without compromising barrel length. Such a definition describes Kel-Tec's RDB (Rifle, Downward-Ejecting, Bullpup), which revolutionized this market in 2010. But you won't find that it applies to the RDB-C because it lacks a pistol grip.
How does the RDB-C operate? For starters, there's an adjustable in-line, short-stroke gas piston system. The valve is positioned above the RDB-C's 20½-inch barrel. The rifle utilizes a seven-lug bolt with the extractor located at the 6-o'clock position to feed and clear the action. When the bolt body reaches its most rearward position, a pair of spring-powered ejectors strike the case and propel it downward through the aluminum-lined ejection port toward the shooter's feet. The return spring shoves the bolt forward and strips another round from the top of the magazine and shoves it into battery.
There's a charging handle located on the left side of the RDB-C near the adjustable gas valve, but its position can be swapped for lefties. When the handle is pulled rearward, it locks into place when engaging a small cutout. As you change magazines, you can either press the bolt-release button or slap the handle down to send the bolt assembly into battery.
The selector switch on the original RDB model has been replaced with a crossbolt safety on the RDB-C, and there's an ambidextrous bolt-release button located near the top of the stock between the magazine well and ejection port. There's also a large, round magazine-release button on the right side just below the bolt-release button. Operating the rifle is simple for both right- and left-handed shooters. Since spent cases are ejected downward and not laterally, a left-handed shooter won't have to worry about hot brass whistling past their face.
The RDB-C's green stock is made from Zytel polymer developed by DuPont. It's well known to be lightweight and extremely durable. With the rifle's center of balance located at the trigger, the rifle's overall length measures only 30.4 inches. It feels great between the hands and offers excellent maneuverability.
Chambered in 5.56, the rifle comes standard with a 10-round Magpul PMAG, but it will accept other AR mags as well.
For G&A's test, I mounted Aimpoint's new CompM5 red dot followed by Aimpoint's 3X magnifier on a flip mount. This combination was the perfect complement to the RDB-C's versatile design. For close, fast shots, the magnifier could be flipped out of the way to allow the CompM5's 2 MOA red dot very fast, both-eyes-open shooting. When I was shooting at 100-yard targets, I rotated the magnifier back in line for more precise shooting. Kel-Tec lists the weight of the RDB-C at 6.9 pounds. With both Aimpoint optics in place, the total weight was 8.4 pounds.
From the bench, the RDB-C performed well with a variety of different .223 Rem. loads ranging from 50 to 77 grains. The best results appeared with Black Hills' 68-grain Match HP load producing a test-topping 1.29-inch group at 100 yards.
The trigger offers considerable takeup but broke cleanly at 23/4 pounds on my test gun - much lower than Kel-Tec's spec of 4 to 6 pounds. Once you shoot this rifle a few times, operation becomes intuitive, although the downward ejection of hot spent brass will teach you where not to position your nonshooting hand when firing from the bench.
The RDB-C is a compact rifle that's an interesting alternative to short-barreled rifles (SBRs) - and for less money.
Type: Gas piston operated, semiautomatic
Cartridge: 5.56 NATO
Capacity: 10 rds.
Barrel: 20.5 in.
Overall Length: 30.4 in.
Weight: 6 lbs., 14.4 oz.
Finish: Matte black (steel); olive green (Zytel polymer)
Trigger: 2 lbs., 12 oz. (tested)
Manufacturer: Kel-Tec CNC Industries Inc.,