std7mag,
I rarely use anything but a singleshot while hunting, unless it is birds (there doubles rule).
For me the "hunt of a life time" was one I spent a half century dreaming about before I could make it happen. That was the moose hunt from that other thread. The story is here
http://www.bpcr.net/forum/viewtopic.php?f=2&t=7311, but the rifle was a substitute. I had bought a multishooter - an original 1895 Marlin made in 1898. I wanted a repeater in case one of Cheyenne's study subjects got lost and came my way. The rifle was completely bubba'ed so it needed new wood, new barrel, new magazine, sights, and some internals. Along the way, I had a set back, so at the last minute the Ballard .45-70 went, and it was a much more interesting rifle. Made in the 1880s and completely original. It acquired more patina and it got the job done. It has also killed many antelope. Of all my rifles, it is the most "been there, done that".
My first elk, antelope, mule deer, and all my Africritters were killed with a Shiloh Sharps. It was .45-90 the first time and .45-100 for everything else. I had bought a .577-450 Martini sporter to take to Africa but boy what a crazy gun those are. The barrel tappers almost 20 thousands from chamber to muzzle. I could not make it shoot in the time that I had. It stayed, the Sharps went. It all worked out. You can read about it here with some picts if you are interested.
http://www.bpcr.net/forum/viewtopic.php?f=23&t=753
Otherwise, I hunt with an original Highwall, also made in 1880s and owned by one family in Wisconsin until I got it. Barrel was rotted to it mutated a few times from .38-55 to .25-20, to .38-55 to .38-72. Antelope and deer and even squirrels have fallen to it. Maybe one day an elk. Super easy carrying rifle.
Squirrels usually get shot with my .22 low wall but I have had other singleshots, including a Martini 1215(I think) and a Ballard #3.
And then there are all the muzzleloaders, especially the flinter that has killed more deer than any gun I own but also squirrels and antelope and probably something I've forgotten. It is a.54 roundball gun, but I do have muzzleloaders of other calibers including 2 .45s that are long range rifles - one for targets one for critters.
That's the bulk of them I think. I have a few "in the works" too, of course, and dedicated target rifles.
I hope all of you get a chance to hunt with a single. They carry so easy, balance well, give up nothing in accuracy, and they have lots of history and are lots of fun to search for, fix, shoot, and everything else.