Jim,

It is not an inertia driven trigger. I just shot a few clays and I have to operate the tang selector to switch to the UB.

Daryl, your sequence makes sense. I am somewhat used to double triggers, this new toy takes a lot of thinking to fire, so much that the clays get in the snow long before I can find the underlever safety, triggers, selector,...But it's so exhilarating!
Is it you I bought the WRichards 21/2 from last week?
Try this link for the pictures of the gun:
http://www.sitemason.com/page/gEyuIM

Rocketman, thank you for the story. It brings so much more flavor to my enjoying the gun and may explain my confusion.

I saw a description of a tribarrel Hambrusch with a single trigger that would fire the barrelsin this order: UB/Cyl, RB1/4, LB1/2.