RDB stands for Rifle Downward-ejecting Bullpup and the 17 points to the barrel length. This variant is the original and features a high-impact resistant Zytel forend with built-in Picatinny-style rail on the bottom for mounting accessories. Like all the RDB variants, it’s completely ambidextrous, accurate and compact. Downward Ejection This unrivaled design sends spent brass downward through the stock, behind the magwell making it a truly ambidextrous bullpup rifle. Gone are the days of hot gas & brass flying out of a side-ejection port… you’re welcome, southpaws. Unparalleled Trigger System Bullpup triggers are notoriously bad, so we tackled that issue head on and won. This trigger is incredibly smooth, with a nice take-up and clean break. Combined with a 1:7 twist barrel, all RDB models offer excellent accuracy. Adjustable Gas System All of the RDB models operate off of the same adjustable gas piston system. This feature allows the user to tailor the bolt carrier speed to eliminate excessive recoil while running a suppressor and ensure reliability for various loads. Caliber .223Rem/5.56 NATO Weight (Unloaded) 7 lbs Magazine Capacity 20rd Overall Length 27.3″ Barrel Length 17.3″ Twist Rate 1:7″ Trigger Pull 4.5-5.5 lbs