I am with this idea!, that happened to me once. +1.
-Add some kind of memory that will remember the ammount of nades (For this example)
Be smart and store your ammo in a house.
A warning should be fine I guess.
It's been worked on that if you have 900 grenades then you buy 3 satchels you'll get 303 satchels.If you then bought 3 grenades it'd go back to 912 grenades.