I bought some beat up ammo cans the other day for $3.99, wiped them down thoroughly with Break Free and now they look pretty good.  I tried fitting various boxes of ammo into them but I found that none of them seem to fit in tightly, so they tend to bounce around.  My question is this - would it be safe to just empty all of the boxes of a particular caliber into the can and just store it like that?  I've heard people say in the past that it isn't so I thought I'd double check before I go ahead and do it.  

My calibers are 9mm, .45 ACP, 7.62x39mm, .223, 7.62x54mm & 12 gauge.

I keep most of my bulk ammunition (not match grade) loose within the storage cans.

Yep, its fine.
I'd use a bin liner and a desicant pack as well, just to be on the safe side.

Yep. After Break Free (or WD 40- cheaper) use a little Brake CLEANER. Wear gloves and use it outside. Better safe........

That's where I keep all my ammo.

I box mine up and fill in the voids with cardboard.

see now Im glad That I have no ammo. I dont have to deal with these sorts of problems

I should be all set on putting them in then because I didn't wipe down the inside.  The inside was already in perfect shape so I didn't touch it.  I should've said that.  Anyways, thanks for the replies.