please note you would not have 100% chance of a crushing blow, the only way of getting 100% is to have a mod on an item which says is 100% CB. with this set up it would be possible to get 5 crushing blows in 1 hit although the chance would be like 0.01%. With these items i believe that the chance to get at least 1 CB is around 80%, with diminishing chances to get 2, 3, 4 and 5 CB's with 1 hit.

i can only think of a couple of ways of getting very high crushing blow on an item. an ettin axe can have 5 sockets so 5 ber runes would give you 100% of a crushing blow with pretty decent damage, i think this would be a real waste of runes and would much prefer a eth ettin axe with a zod and 4 gul's in it. the other way i can think of is a cranium bahser with a ber rune which would be 95% CB.

it would take long time to work out the crushing blow percentages for this set up but it hink it would be around