I found a post which say that SBR AAA kill ratio was 10% max:
What Larry says have flaws, and contradict to to base mechanic.
It should be like this:
1. Attacking fighter escorts roll dice, each 1 is hit, and defender move casualties to casualty zone.
2. Defending AA-gun roll dice, each 1 is hit, and then defending fighters roll dice, 2 or less is hit. Attacker choose his casualties.
3. Surviving bombers roll SBR dice against factories.
In real world, the attacking airfleet would first face the intercepting fighters, and then the escort fighters would do dog-fight. Later, the bombers would face AA-fire at the target. This AA-fire killed historically less than 10 % of the aircrafts. Using Larrys rule where AA-guns target bombers, you could be lucky and roll two 1’s and kill both attacking bombers, and get an unhistoric result of thousands bombers killed and no harm to the factories. Since its an abstract game, let the attacker pick a fighter as casualty to represent a % loss, and still have bombers survive to SBR.
He is talking about an older version of SBR (AA50 Anniversary).