Ammo boxes are items that are used to replenish weapon clips to allow them to fire. Each weapon has its own ammunition, and therefore are not cross compatible with each other. Note that in Hardcore mode half as much ammunition will be contained in uncollected boxes compared to Softcore.
Each box of ammunition has filler text and some humorous details included in their textures.
Pistol Ammo has the labels 'Federal Junkies Incorporated', 'Gun Junkies Federal Series', 'National Rifle Association of America (Incorporated 2156)' and 'Under the Hood (From 2157)'. The instructions 'Do not eat, dring or hope // Kill 'em all. Let God them sort // Kill or Baus' appear as well.
Magnum Ammo also has the label 'Under the Hood (From 2157)' in addition to 'ACC Federation'. The instructions 'Kill 'em all. Let God them sort' appear again, as well as the filler text 'Some Bullshit over here. // Typing Typing Typing. // So here I am. // Big as Life, but twice Ugly. // Boobs Boobs Boobs. // You don't see this!'.
Submachine Gun ammo is labelled 'Under the Hood (From 2157)' and 'Matriot // Fun Club'. The warning 'Inappropriate for Children, Birds and other Fauna. Another Bullshit text to fill.' can be seen, in addition to the comment 'As I walk through the Valley of the Shadow of Death, I take a look at my life and realize not much left. // Cause Black and White and Green // And even Yellow are still a Bullshit Colors for the same Blah-Blah-Blah. // Nobody reads this anyway!'. Strangely, instructions for Haydee herself are present; 'Turn your back to the ledge. // Beware of Boobs, Tits and Breasts etc.'. Also, despite being clearly labelled as '6mm Auto', the text '12mm Automatic' also appears, the same calibre as the Magnum.