I have read at this site and at google that rotation of the bullet corrects the deviation from the target.
Does anyone know how this is achieved?
If the bullet spins then conservation of angular momentum means it wants to keep facing in the same direction. That doesn't affect its trajectory directly, but it does tend to prevent it from tumbling end over end, and if it tumbles then there are wildly varying aerodynamic forces on it which push it all over the place.
No amount of material is homogeneous and there fore subject to deviation in flight, by means of rifling grooves in the barrel, the bullet takes to turning slowly giving it stability and is always correcting itself in flight, this gives a more accurate shot to target.
Your officers had it wrong.
A bullet does not drill, rather "punches" through as in nail with high kinetic energy. In fact, soft, fibrous materials packed densely, use the "spin" to slow down or stop the round, by entangling and trapping it. A bullet spins laterally (as mentioned by @T.E.M.S) to keep it on a straight path.
An arrow (in archery) has flights (feathers) in a slight "corkscrew" configuration to achieve the same goal.