Kel-Tec RDB: A Unique Bullpup Rifle Design

posted on December 9, 2020

To say the Kel-Tec’s RDB is an unusual take on a bullpup is understatement. The firearm’s initials—which stand for Rifle, Downward-Ejecting Bullpup—tell only part of the story. It was a big hit at the NRA Annual Meetings & Exhibits in 2014, where it was first unveiled to enthusiasts.

Bullpup designs traditionally eject up top or compromise ambidextrous use by tossing empty cases to one side or the other. In this rifle they leave from behind the magazine well and head toward the ground. The piston-driven RDB is semi-automatic and uses a short-stroke, gas-operattion system.

Versatility is key in the gun, and includes a regulator on the barrel that allows owners to adjust the amount of pressure tapped off for cycling (for suppressor work or when using light loads). It’s also modular, consisting of four assembly groups—bolt group, barrel group, grip group and where the serialized component resides, the receiver group. H&K-style push pins make disassembly for maintenance, repair or replacement fast and easy. Dual ejectors on the bolt ensure operation from unconventional shooting positions, even upside down.

All four versions available today are chambered in 5.56 NATO, feature 1:7" rifling, have a rail on top for optics and accept standard AR-15 magazines. That’s a huge advantage for enthusiasts who already own a modern sporting rifle.

Last year the Kel-Tec RDB was the seventh-most-poplar semi-auto rifle in sales on It’s gaining steam, too, because it was No. 8 in 2018.

You can expect it to move up in the rankings when this year’s totals are in, thanks to the company’s introduction of the new Defender RDB model. Its barrel is 16.1" in length, the buttstock is adjustable and it comes with an M-LOK-compatible aluminum handguard. MSRP is $1,072 to $1,142, depending on options.

The RDB Defender version has the same length barrel, but ships with folding sights and no pistol grip. Price varies from $1,036 to $1,108.

If you’re after hogs or hoping to fill a tag on opening day the Hunter model may be more to your liking. With a sleek fore-end, 20.5" barrel and swivel stud up front, expect it to set you back $930 to $1,002.

And finally, the RDB 17 wears a 17.3" barrel. It has a Zytel fore-end, Pitatinny on the bottom for accessories and MSRP is $930.


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