I couldn't find anything like this for CSS, but there is such plugin for CS1.6
HERE.
Version for CSS could be alittle different, if someone would like to create it:
- pick up ammo left and not loaded (i.e. if the player died with 28/46 ammo left, only 46 bullets can be picked up)
- pick up ammo of the same type only (player running with AK47 can't pick up ammo from player, who died with MP5 i.e., but can pick up ammo from player, who died with AK47 or M4A1).
It would be great to have such functionality I think.