Sig, the only problem with an interchangeable bolt gun for those two would be the issue with having different rim diameters, needing different bolt faces. Also there would be the problem of needing two different types of magazine. However, since you mentioned it, I thought about it for a few minutes, and if a guy had a rifle with a removable bolt head (along with the machine tools to do the work himself), he could have two different bolt heads for the two cartridges. Kind of like on a savage 10/110, only in this case a magnum size bolt head would most likely have to be bushed down to fit the colt rim. It's a decent idea, though it would cost more than building two separate rifles if you had to pay for the work I imagine.
Scorch, that's pretty much exactly the type of info I was after, though I've heard or suspected the biggest part of it already, I still like hearing from the folks on here. I couldn't find anything on the carbine you referenced though, just the 22 tcm rifle. If you have or can find a link, I'd greatly appreciate it being posted. It definitely sounds interesting.
Sevens, just like you, I'm not a typical rifle buyer. I like odd stuff, or just something different. I don't know what it is about bolt guns in pistol calibers that I'm attracted to...actually I do.
I like the fact that I won't just burn through ammo super quick like with a semi-auto or even a lever gun can. I don't have to chase brass near as bad as the others, and they're not "normal". I'd love to have one in everything from a .32 something up to maybe one of the .50 caliber handgun rounds, mostly just cuz.
Shootist, where I shoot and hunt, there aren't a whole lot of places to shoot at anything beyond 100 yards or so. There are some exceptions, farm open fields and such, but (for deer at least) there's usually enough hunting pressure on public ground that the game is moving at a decent pace there anyway. The rifle that you're building sounds like it'll be a sweet little thing for the woods.
Jim, as far as the size and weight of the rifle, I'm used to carrying heavy guns anyway, and there aren't any appropriate sized actions around that I'm aware of. I'd love it if someone could produce an inexpensive action that was scaled down for pistol cartridges, but I don't see it ever happening. As for the DeLisle carbines, I've never heard any official numbers that were made, but I've heard several things they were used for. One being executing enemy dogs, and another that I hear often is to take out enemy sentries (spelling?). Not sure if any of it is true or not, but I think they're neat carbines anyway, and I like the fact that they found a use for the otherwise unusable rifles.
Thanks for the replies y'all, if I end up getting one of these put together, I'll post some pics if anyone is interested.