RDB Gas Adjustment video.

One of the key features of the Keltec bullpups is the TUNEABLE gas system. Most rifles only feature an adjustable system (somewhere between 2 and 8 settings)
The Rdb has over 20 settings! Some folks get overwhelmed with the initial process and then get mad when the rifle malfunctions (Usually when they switch from a brassed cased to steel cased without changing the gas settings).

The benefits of a tunable system are reduced wear and tear on the rifle and lower felt recoil.

In my experience with this rifle, you really only need to know (2) settings. Those should be for:
50-75gr Brass Cased Match ammo (usually really low)
Steel Cased Ammo/Tula or Wolf usually (These usually require more gas to operate vs Brass cased)

*Suppressed use depends on the suppressor you have selected. A flow through can is what I use, and I have to reduce the gas setting by 1 vs no suppressor.