Matt I'm from Wisconsin myself, I got my first Underhammer a few years back, I bought it because it was dirt cheap it was an old .45 chunk gun with a very rusty bore, I swamped out all the rust and actually got it
shooting pretty well, I spent several very enjoyable days shooting it
and came to the conclusion that underhammers are incredible, I think the reason you don't see many is that to the unitiated they're considered pretty ugly (I sure thought so) and they are unique or different which seldom results in wide acceptance, but to me form follows function.
I ended up re-barreling mine with a .40 cal. Grn. Mtn. and I absolutely love this gun, it's still ugly, but then again so is my main Dog, but
when I want to spend a nice day alone burning some BP it's invariably
the rifle I grab. Instantaneous ignition, my sight picture isn't disturbed by getting cap debris in my face, and I can re-barrel in a matter of minutes
almost no moving parts. I think if breech loader were never invented Underhammers would definately have become the norm. Regards fredj