The gun is an underlever. There are two triggers, the front one operates the RB and the UB(under). The rear trigger operates the LB. The triggers do not operate unless the underlever is returned to its full position after cocking the gun. Therefore the underlever serves as universal safety. In this position I can shoot the RB pulling on the front trigger and the LB pulling on the rear trigger. To shoot the UB I need to slide the tang selector to forward position and pull the front trigger. The tang button, I believe serves only as barrel selector between the RB and UB which are both operated by the front trigger.
Silver, everything is clear. Just imagine you got ordinary sxs gun, but with extra 3-d barrel (UB) and you'll figure out maker's logic.
Nice gun!
