Wilbus,
not doubting you, but I've rarely seen a bomber take more than 2 hits to the wings, at any point along their length. To the wingtips I've never seen one survive 2 hits, rarely even 1. I knocked out a B-26 and A-20 the other day like this, and got an A20 shot out from under me by a single ping to the wing. You don't want to hit the engine, either the tip or the wingroot. If you are shooting fuselage you can wait 5 or more hits sometimes before you even notice damage.
My aim in an Ostie tends to be a little lagged anyway and I tend to hit wings and not the fuselage. Barely ever used the PT 40mm but can remember one time several tours ago where I was knocking out fighters with it like crazy.
-Soda
The Assassins.