I use 6x100 lbs bombs, 4x rockets, and strafing to kill tanks.
I have no fantasies about the accuracy of my ord lobbing skills, so I use my own method low-alt level bombing: set salvo to 1, line up with the panzer at about 1~1.5k alt AGL, medium speed. Approach level and when distance counter turns to 1.0, get ready to drop bombs. As soon as distance changes to 800 and the enemy tank starts to disappear under the nose, quickly tap the bomb drop button 6 times in rythmical interval. (Of course, you must change the ord selection once, since you are dropping two external bombs, and four internal bay bombs). By dropping it this way the bombs will fall in a straight line with each bomb crater adjacent to the other - a bomb blast pattern of a long rectangle forms. Usually with this method I can kill an enemy tank close to the base within 2 minutes of take-off, without having to grab altitude for angular bombing.
Then I use the rockets - but I admit my hit rates are very low. So rockets are usually used to damage Ostwinds.
And, after that, with the guns I can strafe and damage about three~four enemy tanks. If I want more than just damaging it, I can blow up Panzers in one pass. I approach behind a tank from far out, go in at at a low angle under 30 degrees in most cases. Then I reduce throttle, zoom in max and, and fine tune the plane by quickly trimming it exactly right so it is stable.
And when the distance comes within 600yards, I open fire. Hold the cannon button down until my IL-2 almost collides with the Panzer. My target is; the rear hull, or turret rear, or the turret/hull joining area. As I fire the cannons I can see the globs of hit sprites smashing against the tank, and then finally the globs grouping into one - indicating the rounds from both guns are landing at right convergence. With a little bit of luck, as the distance closes down to 200 yards and less the Panzer will blow up. If it does not it is at least seriously damaged.
Therefore, IMO, the IL-2 guns are powerful, about exactly good as I would expect a true anti-tank aircraft gun would perform.
