Well, thanks for the information.
I'm not sure how practical it is to have a handgun and a long gun that chamber the same ammo. If my pistol shoots the same ammo as my rifle, why carry the heavier gun? If I am going to carry the bigger and heavier gun, I think I want a more powerful cartridge that justifies doing this.
Having said this, I confess to owning a couple of pistol caliber carbines, but to me they are toys. I see them as fun shooters, not serious rifles.