Daryl,
Funny, you beat me to it. I was about to mention Jack Lott and his .577
http://forums.nitroexpress.com/showflat.php?Cat=0&Number=294716&an=0&page=0#Post294716
Add in the guys like Ray Meyer, Cal Pappas and more that have collected and hunted with vintage hammer double rifles. Lott in his various writings mentions quite a few names from the 1950’s and 1960’s.

PH’s in the 1870’s to early 1900’s saw a lot of dangerous game killed with hammer rifles.....because that is what they had. Maybe these days a PH would have to see a guy use one to become comfortable with the idea?

Me? I hunt Jack Rabbits with hammer double rifles. Are they dangerous? Well ask the Knights in Monty Python “Search for the Holy Grail” about the ferocity of the “killer rabbit”.
- Mike