The Germans kept track of how their planes were shot down. They assumed that bullet holes in the front came from a bomber's deffencive guns and those with holes from the back were downed by fighters. The bomber gunners "Claimed" they shot down over 28,000 Nazi planes, But German records show that it was closer to 10-11,000, IIRC! The vast majority, 2/3rds, by B-17s!