Think in this Idea, Wolfram or (wolframio in Spanish) mean that all the bullet can be of a low caliber with the same power of penetrate an armour. Other materials like Molybdenum Vanadium add to this material and put in a bullet, give a power destruction armor incredible. This idea wasn't new, the Pak41 try to put in practice, but the German can't have this strategical materials in quantity enough.
Imagine, a antitank rifle of 13mm introducing a bullet in 50mm of iron. Logically this elements can used to reinforce the armour, making this more lightweight.