I try to have at least 1,000 rounds for any working/using gun that I have. I have quite a few guns that don't see much use but I still keep a decent stockpile for them. I tend to use large GI ammo cans for most of it. I label them with masking tape and a marker for easy reference.
"A Liberal is someone who doesn't care what you do, as long as it's mandatory". - Charles Krauthammer