Kel‑Tec RDB Defender | 5.56 NATO | 16.1 in | RDBDGRN

The Kel‑Tec RDB Defender is a compact bullpup carbine built around Kel‑Tec’s downward‑ejection RDB platform. This configuration preserves a standard AR‑15 magazine interface while shortening overall length for easier handling in confined spaces. For a matched optic under $1,000, the Vortex Strike Eagle 1-6×24 pairs well with the RDB Defender’s intended role and mounting options.

Applications: range training and compact‑platform target work.

Product Specifications

• The manufacturer is Kel‑Tec.
• The model/series is the RDB Defender.
• The manufacturer part number is RDBDGRN.
• The UPC is 640832008098.
• The caliber is .223 Rem / 5.56 NATO.
• The action is Semi-automatic.
• The barrel measures 16.1 inches.
• The rifling twist is 1:7.
• The finish is listed as OD Green (receiver) with black metal.
• The stock material is Polymer with a collapsible description listed in sources.
• The handguard is an aluminum M-LOK design.
• The safety is Ambidextrous.
• The rifle is compatible with standard AR-15 magazines (magazine capacity varies by configuration).
• The rifle uses a detachable magazine.
• Notable feature: downward ejection bullpup for true ambidextrous operation.

The RDB Defender combines the compact footprint of a bullpup with familiar AR‑15 magazine compatibility and an adjustable gas piston system. Its M-LOK handguard accepts modern accessories while the downward ejection and ambidextrous controls make it straightforward for both right- and left‑handed shooters. The platform is well suited to shooters who want a shorter carbine profile without changing magazine ergonomics.

Customers commonly praise the RDB series for its unusually smooth trigger feel compared with other bullpups and for the practical ambidextrous downward ejection system that keeps brass and gases clear of the shooter.