I mostly use plastic MTM ammo boxes; 50's and 100's, but mostly 100's. Also I have a 1-gallon paint can full of my favorite .45 Colt load (well, it's only 1/3 full right now) and a 1 pound peanut can full of .38 Specials.
GI ammo cans are probably the best way to store hundreds of bulk rounds. The plastic boxes I think are the best way to store 50 or 100.
"The only way to stop a bad guy with a gun is with a good guy with a gun"