Are tail-gunners bullet-proof?

[Jack_Aubrey]

It's not that difficult, I get my gunners killed more often than i like; but of course when proper technics are used.... most of the times we (because we try always to fly 4 bombers in diamond) get fighters coming to us from our six.... thats almost a secure kill for our gunners, but if you try the frontal or falling over us from 2-3 or 10-9 you probably gonna hurt us badly or kill our crew members.