All of the comments are true and helpful. Other considerations.
Which Sprite is which: if you fly a plane with machine guns and cannons, often time the machine guns will find the target first because the rounds have higher muzzle velocities. So if you're in a Spitfire you could be hitting the bandit with the two machine guns and missing with the 20mm cannons.
Solution: Make use of two triggers on your joystick. Have one set for Machine guns and a different one for cannons. use the machine guns to range the enemy, then position for a little more lead and fire the cannons. Practice this and it will save you cannon ammo and help you get more kills because it will allow a higher hit percent for your cannon rounds.
Scattered Rounds: Convergence means there is only one point where the rounds are concentrated. short or long of that they spread out. Add to that planes are at different attitudes toward each other. this means rounds will be spread around the enemy aircraft over time. So lots of sprites can mean you hit lots of different parts only a couple of times. which may not be enough to break them.
Solution: try something with concentrated firepower so sprites usually mean victory. P-38, 110, 109 w/30mm.
Crossing speed: If a target is moving very quickly through your guns sight due to scissor maneuver, or a crossing shot, the number of rounds you can land in the same place is decreased. So you may just put a few holes in him.
Solution: 1) Getting a kill on a high speed crossing shot required lots of firepower. Many pilots, even the good ones, are surprised by a crossing shot (snap shot). They feel they can survive a fast scissor long enough get there opponent (focused on making a shot) to slide out in front after a few turns. Heavy firepower that kill a bandit on a quick snap shot can make for a lot of easy, quick kills enabling you more time to get in position for the next bandit in. P-38, 30mm equipped German planes, N1K1, Hurricane C, La7 with
(3) 20mm pack, 110 w/4 20mm, A-20 with 8 50 cal in the nose.
2) Other wise you need to saddle up behind him so you're firing more of a tracking shot. This effectively slows down how fast the plane is moving through you firing solution. The trade off is the smaller size of the silhouette (or cross sectional area) that your trying to hit. so a plane with lots of ammo is your friend where. F4U, Pony, hellcat, Jug, P-38,
Personally, I don't like have to take that long to saddle someone up, and stay there for a longer tracking shot because I'm usually picked by his wingman by then.
Hope that helps