Some reason you can't stack amour heavy ammo abilities. For my stacking- "The Artmamentarium" - Carry more ammo for heavy weapons (+1) "Karb's forceful greaves" - "Carry more ammo for heavy weapons (+ ?) and on top of that im using hezen vegeance.. Meaning that my rocket launcher because of its abilities has 3 pieces of ammo plus the artmanmetarium makes it 4 but after equiping the Karbs forceful greaves there is no +1 to my heavy ammo.