I've noticed virtually the same. Still can find some 40S&W, occasional 38spl, and pistols/bolt rifles/shotguns are in stock (mostly). 223, 22lr, 9mm, and mostly 7.62x39 are GONE.
Something that trips me out is... what's with the run on the 22 ammo? There's virtually no threat of a .22lr ban in any way shape or form. Maybe the fact that it's already cheap and easy to stock up on combined with a fear of an excise tax on it?