I have shot down 20 vs the 4 that have got me. Looks like I get more than I get got, and I fly planes with 50 cals most of the time.
So ya I think your exaggeration is a bit out there.
You have all of 7 kills this tour of B-17, 6 flying F4U-1A and 1 flying the P-51D, against 1 death. That's not many for a whole tour, you must be ignoring buffs a lot of the time for whatever reason. Also the raw stats don't tell me much about hows of these kills, such as whether you had help in attacking the formations or not, whether or not you pulled off when the defense fire proved too accurate, how often you RTBed with oil out, or what have you. My own K/D against B-17s and B-24s combined is 9-0, but I will flatly tell you that comes from the simple expedient of only attacking buffs in good situations and pulling off of them if the gunner is too apt.
Against B-24s you have 2 kills, both in ship guns. Your single death to B-24J is in a P-38J, a better than average buff hunting plane, strongly suggesting you did run into a competent buff gunner and it wasn't a "free kill" at all.
Against the more lightly defended Lancasters you have 9 kills, all but one of them in the P-38J. The P-38J is quite a bit better than average for buff-hunting, packing a 20MM cannon and 4 fifties in the nose for concentrated firepower and no convergence issues. And yet you, a relative "experten" in this game, still died twice in your P-38 against Lancaster formations. I suspect that what happened here was you trying to prevent Lancs from from reaching some important objective such as hangar destruction and you were forced to adopt a less-than-perfect approach to do so in a timely manner, as happens often in the MA. But there is now way of knowing.
The story of your stats is that you don't hunt buffs that often, when you do it is often in a plane that is above average for taking on buffs, and even though you are an experienced pilot, they still get you regularly. Pretty good demonstration of what I'm saying.