There is a lot of folklore and legend about fighter pilots in ww2. but i will tell you yank pilots only broke off engagement for a few reasons....no ammo ( and then a few snookered LW pilots to bail out as they were on their tail ), low on fuel ( again...several ended up POWs rather then let the one get away especially jets), lastly the hun was on HIS ass ( and this was a desperate act of survival ). from what i know of these guys and what i have read it would have been a desperate condition for them to give up the pursuit. i give this a ( if its true): he (galland) did something bizarre at the moment they had to make a decision as to where they wanted to get home that day or risk bellying into germany and sleeping as a POW that night...that is the long and short of it.
look, just about every fighter pilot has helped to get the enemy off of someone in his SQ or the battles 6. so he would have known what a 190/109 firing would have looked like. no way would he have bought it was some nazi secret weapon to install rear firing guns. if 4 'stangs gave up on him...they passed the "point" and LET him be. he didnt out fox them...they let him off the hook....until the next time...