Wen you use the Visor and look around you see instandly what kind of weapons/ammo theres laying around, exept for Hand Granades...

Wen your looking at a Box of Handgraneds trough the Visor is shows up as an Ammo Cash with a Bullets Symbol, and theres nothing to tell you its granades and not bullets untill you actualy get with in direct visual range of the open crate and can see the inside of the lid with the Granade symbol.

So my sugestion was to change the Symbol on the Visor for the Hand Granades to the actual Granade symbol like everything else has its own symbol in the visor, so wen your loking for Granades desperately you can just find the right box you need.