Well, I'm pretty new to the whole bear canister thing myself despite having backpacking for a time now. I've asked questions on the whole smell thing and from what I'm getting, you might as well put anything that smells good in a bear can for sure. Anything else that smells(pretty much everything), try to fit it in. So, if you've got room for your ammo after food or anything like that has been put into your bear can, might as well toss the cartridges in too my friend. It'll take expediency, despite what others might tell you, such as "make it fit" or some half-hearted advise like that.