These are slow zombies.
The thing is, regarding hat you said about shotgun vs. pistol for close range, unless you saw off some of the shotgun's barrel, it will be extremely cumbersome indoors. That is where a pistol will really shine. Also, considering the size of ammo, if I had to chosse between shotgun and pistol, I'd probably choose pistol, as the smaller ammo will let me carry many more rounds.
Nolifer, I be likin' that idea! We bassists could unite, using T-40's and B.C. Riches to bash every zombie that comes near!