UO: A neat reminder is that many firearms don't take the same ammo type, some take 7.62, some take 5.56, some take .388, and some take unique types, like 12 gauge, Rockets, grenades, there's a number of ammo types. Each casing says which caliber it is at the bottom, so it's easy to remember.
*UO takes the empty shell out from the water, the shell is now cold to the touch, and safe to handle. He hands it to PM.*