Trying to find a way to track various types of ammo and armor degradation on a custom sheet.

Im not the GM for the game just making the sheet and playing. There are various types of ammunition and armor slots head, legs and torso have armor degradation. The gm doesn't want to leave it up to or trust players to subtract the values. Any suggestions? I thought about just making a macro for him that just subtracted 1 from the attr but I don't know how to call individual players in the macro and i would have to make one for each ammo type and armor piece.

You'd need the API to actually change values in the attributes; macros can only call/reference them. There are API scripts that help with ammo tracking, though.