You're aiming the shell and then aiming again. You aren't tracking because by definiton it's single fire. As I said, tracking is firing at a moving target, tracing their movement while firing and then tracking from target to target firing in bursts (or holding the trigger down if you're that way inclined
![Stick Out Tongue :p :p](/styles/default/xenforo/vbSmilies/Normal/tongue.gif)
).
That's target acquisition so comes under aiming. You aren't tracking it. You're aiming and firing. If you were firing say a laser beam at it and had to follow it as it moved around with the laser beam that would be tracking.
I think the problem is you're using the word tracking as a synonym for acquiring a moving target. Think of it like this: acquiring the target is aiming and then maintaining fire at it while moving is tracking.
So somebody good at aiming bad at tracking would hit their first bullet on somebody and nearly kill them due to the good aim but their poor tracking allowed that person to get away because they couldn't track his movement behind cover and maintain fire.