Like others have mentioned, and I repeat;
1. Seeing "lots of flashes", actually means that your aim was inadequate. It means that your rounds are scattered all across the surface of the target plane - hence, "lighting up like a Christmas tree".. Ideally, you should only be seeing one or two sustained flashes - which means your bullet stream is grouped and concentrated at a very tight area, and thus, is visible as only one or two flashes.
2. Seeing the plane flying around does not mean "no damage." Some damages are easily perceivable, in the form of fuel trail, smoke, fire, debris, etc... while other internal damage may not be so obvious. You never know if you just gave him a pilot wound, or busted his guns, or blew his oil pan.. and etc.
3. The fact that you're pulling hard enough to black out, does not mean the enemy behind you will be doing the same. That only happens if the enemy behind you follows your exact same turn radius (or tighter turn radius) at exact same speeds. And even he does, he may have pulled a totally blind lead shot just before the verge of total black out - which is fully possible.