Since damaged bullets can damage your gun, it's important to know which stack of ammunition in your inventory is pristine and which is not. You can see this by the normal mouse over effect and wait until the description window is loaded in. To improve the inventory and make it more user-friendly, you could color the slots in the inventory based on the current status of the item which takes place in those slots. i.e.

empty slots = grey
runied = red
prisitine = green

This way you can easily see which stack of ammunition is damaged and which is not. You just need to open "Tab".