I only speak for VF-17 when I say this, but the reason we didnt score very many kills is that our job was to protect the bombers or clear airspace. We never really got the opportunity to chase down and kill the enemy. We could push them down, but then we would be out of position to protect the bombers. While the B-29 is so fast the Japanese got one head on pass, and then it turned into a tail chase, which is bad enough against B-17/24s