I think you're really over-estimating how many rounds you are firing, and how many are hitting.
Are you seeing nonstop hitsprites? I doubt it. You don't see the hits, most likely you're not hitting. You will almost never "hit" a plane without a visual marker telling you "hey, this round hit, great shot!"
How many SECONDS are you seeing constant hit sprites? If you hit ANY fighter in the game for more than 2 seconds "steady" 50cal fire it is gone, period.
You really need to post a film, I think. Definitely pilot error. We're willing to help, but we need more to work on.