Steel is of course much lighter in weight than lead. The going up two sizes is to bring them to similar weights per pellet. Going up 3 sizes brings them much closer ballistically. Having less sectional density steel of course "Sheds" velocity much quicker than does lead. This is why it has to be started faster. It Doesn't "Get to the Target Quicker" because it is lighter. If started at similar velocities the lead will get there quicker because it is "Heavier". Although admittedly much more drastic but throw a golf ball & a ping pong ball with the same force & you will very quickly see the difference sectional density makes.
