A short Shank comes out of your Tank barrel and stabs any enemy it hits, it does not alter the terrain but it can pass through it. Though the effect radius is not clearly determinable, there is a practical trick which helps you calculate whether Shank will hit your target or not, based on the length of your shot bar (the "white part" of your shot bar, which can be calculated in "power units" ranging from power 0 to power 100). Specifically, if the distance between you and your target is less than ~29 "power units", Shank will hit its target.
Is the tank too far for the Shank to reach it? Well, there's a solution for that! The Dagger can reach further than the Shank can for the same amount of damage. Using the above trick to determine whether your Dagger will hit or miss, you will find out that Dagger will hit its mark as long as the distance between you and your enemy is less than ~46 "power units".