Yeah, 500 rounds may seem like a goodly amount. Then again, I started a thread a while back about "How much ammo is enough?" Got some interesting replies....
http://thefiringline.com/forums/showthread.php?t=470291
I'm working at restocking my ammo shelves, which I let get somewhat depleted. As a base supply I'm looking to have on hand on the shelves 1000 rounds for each handgun. Now it may be different bullet weights and styles like .38 Special in RN lead, JHP, FMJ, etc. I pick up a couple boxes or maybe a bulk batch when I can. Yesterday when I was at Cabelas and they had American Eagle 158 grain round nose lead 400 round bulk pack (8 boxes in a GI ammo can) on sale from $165 down to $155 and I had a $20 Cabelas Club coupon for $20 off my next purchase so I got it for $135. They went on the shelf next to the other .38 Specials, which include 125 grain JHP, 130 grain ball, and 150 grain lead. This is just what I want to accumulate for on hand shooting and does not include long term cached SHTF supplies, which will obviously take longer to build up and some testing to find what shoots best for me in my guns.
Can you ever have enough .22 LR? Not when you can easily run through 500-1000 rounds in a day at the range with three kids... It's cheap enough that picking up a brick or two is affordable and you can try out a lot of different kinds of ammo from different makers to see which one each of your .22s likes best.
For rifles it depends on which ones I'm stocking for. For my oldies I want to have 100 rounds each. I have a thing for old military bolt actions, a couple of which are old enough that they are considered C&R guns. I have a couple of SMLEs that I wnat to keep the brass fired in each one seperate so that if I reload at some point I will have brass that is fire formed to that rifle and can neck size only. This is a particular issue with these rifles. Fro my hunting rifles I think I'd like to have maybe 500 rounds each, so for instance .30-30 I'll probably split that between 150 grain and 170 grain loads. For what I call "Modern Military", .223 and 7.62X39, I would like to build up to at least a couple thousand rounds of each at minimum as they seem to go so fast when playing with steel plates....
There are other threads discussing ammo cans and storage methods, use of purge gasses, oxygen absorbers, and dessicants among other things. One of the basics of ammo storage is to keep it cool, dry, and away from large or rapid temperature changes.
I'm getting there...