Actual offline playing with those P51 drones circling'n circling is really boring.
But we could load a film and play offline into the film against your own plane. You can fire and hit , but always with no damage effects just to keep all the filmation sequence intact. Your plane starts just behind your film plane, same angle, speed and alt, but just behind it. You can follow your own plane and practice firing against it. Once the film ends, it restarts but your current possition is kept.
An example:
You go offline with a SpitIX and start filming and doing a sequence of maneouvers, then stop film. Now you activate the filmation selecting as own plane a 109F. You start behind the filmation Spit and may try your gunnery and ACM following your filmed Spit.