User blog comment:Axelth/Ammo consuming/@comment-24021074-20140223224850

Ah, found the calculation, if it was still missing for you:

1 - (1 - 0.2)(1 - 0.2)(1 - 0.2)(1 - 0.5) = 1 - (0.8)(0.8)(0.8)(0.5) = 1 - 0.256 = 0.744

1 = is for the change to consume ammo (so it's the normal 100% ammo consume). Helm 0.2, Plate 0.2, Box 0.2, Gun 0.5.

So yea... Hope this helped ^^