I keep a couple thousand rounds for my .22 LR(s) As far as a shotgun, I don't go below12 gauge. I keep two cases of birdshot. (400?, Something like that) and about 50 of buckshot. Federal is making 1 shot again! I would most definitely seek this out, the ballistics are amazing for defense.
As far as my rifles, I keep between 400-600 for each, .223 a little more. Miscellaneous handgun ammo, not a whole lot as I view a handgun as a means to get to a rifle and in my case, a carbine.
Also note, I do not "hoard" ammo. I actually shoot the stuff and replenish as needed.
“Dying is easy, living is hard,” -James Hetfield
"Living is hard, writing is easy" - Buggyout