You're not thinking outside the box.
A semi auto shotgun with a huge ammo load in a box or ammo drum would be my choice of firearm..it does the job up close and far enough for me to get away..and with area effect damage.
As for 'other'... well, thats the out of the box thinking one.
I'd take along a good supply of dermestid beetles (Dermestes maculatus). These are the beetles that eat dead flesh in a matter of hours.
Now, granted, a matter of hours wont save you from a zombie hoard but if you saturate an area with they're like a self-replicating landmine. Any zombie coming inside the area will get gobbled up by them. And they expand as they reproduce. These beetles do not eat living flesh but will rabidly consume any decaying flesh (including gangrene on a living person)..and the undead are certainly decaying.
