I did some basic testing of the B-25H cannon last night.
Here's a few facts we discovered.
You can sit behind a formation of heavy bombers and pick them off with the cannon at ranges out to 2,000 yards. I fired 8 rounds at 2k to score 3 hits. One hit is more than enough. Closing to 1,500 yards, I needed 5 rounds to score 3 hits. Practiced using .target command. At 2k, aim for upper ring to get bullseye. At 1.5k, aim mid-way between 2nd and 3rd ring. There's no defense against this for buff pilots, other than to maneuver the formation.
One issue. The cannon fires with the all guns trigger unless you have bombs aboard and select the bombs instead. I use secondary trigger to squeeze off cannon rounds.
Those 8 fifties will shred anything that gets in the way. Very concentrated firepower.
My regards,
Widewing