I've heard from my uncle that he knew a guy that carried .36 cap and ball in a cut down 1851 Navy because it's "not a firearm and thus didn't require a permit to carry it."
Despite being ok under federal laws,,,,,,I'm positive state & local laws took a different view.
(I tried the same thing myself & it didn't fly...state and local laws called BP "guns")
Anyhow - along that line,,,,,most of you newcomers don't go back far enough - 1998,1999,2000 - to remember when CCW was a "privilege enjoyed by only part of the US" - as represented here on TFL.
At that time, the real darling of CCW was - the 9x18 Makarov.
Years prior to that - when concealed carry was a crime in most of the US, the overwhelming favorite was - the .25 acp.
Even a major company - Ruger - was so dead set against civilian carry, they refused to make anything, other than the SP101 (which was really only aimed at the LE market), for concealed carry. It wasn't until long after old Bill kicked the bucket Ruger went down that path.
I prefer to watch the "new stuff" come out and see how innovative they can get. Those tiny pocket .380's just fascinate me no end.
I'd really like to see someone bump up the caliber a bit to something in the 40'-ish range, yet still keep the power level down.
Maybe a 5 shot - .40 or something.
Obviously not the .40 S&W, but, something with a lot less operating pressure.