I'd just buy normal rifles in .22LR, .223 (5.56x45), 7.62x39, .308 (7.62x51) and 7.62x54R. Normal handguns in .22LR, 9mm, .357mag and .45auto. This probably covers most of the calibers the home stockpiler is likely to have large stocks of (your .357 will also shoot .38spl, which is more likely to be stockpiled than .357).

You might want to go 1:8 or 1:7 on the 5.56mm. The heavier bullets need a faster spin rate to stabilize.