Getting out of the turret in an emergency means getting your parachute on, turning 90 degrees, opening the doors and falling into the ice cold sky at 18,000 feet.
ThamMalaysia - The rear gunner's job was primarily that of a lookout. It was his job to warn the skipper of an approaching fighter so that evasive action could be taken. Later on in the war, the Rose Company developed a rear turret for the Lancaster that was equipped with .50 calibre Brownings but, even then, shooting it out with a German fighter equipped with 20mm cannons was a bit of an uneven match.
IMO and with the benefit of hindsight British armaments were obsolete, they actually had Gatling guns but military command wouldn't fit these to warplanes because they thought the gunners may waste too much ammunition. And if you've ever sat on the strap seat in a ball turret of a Lancaster you will understand they were made for extremely small people and you had 2 noisey guns with hot breaches right beside you, they were not designed for human Comfort or safety, often the poor old tailgunner was hosed out of the turret because one hit from a large Calibre Shell basically you exploded with hydrostatic shock. It was not untill latter on in the war, after losing very battle for 3 years against the better equiped German wehrmacht and Luftwaffe and entry of Commonwealth ANZACs & American forces that the English up sized their calibres in their Spitfires and Hurricanes and Bombers to 50 cals and bigger, they also started to improve their armoured tanks, that came far too late to be effective. Most the time the airman & poor old foot soldier was given a WW1 Lee Enfield 303. You could say that they were very unlucky being in a war but others may say that War was Darwin's theory for survival.
tail gunner where lucky to last more than 15 seconds in combat but my grandpa survived every single last mission he went on . hard ass he was . didn't pass away till he saw me one last time .
Frankly, a single 20 mm Hispano, or even Oerlikon FF with perhaps an extended barrel for greater range, rather than four .303 pea shooters, would have been far more lethal. And they could have added in a slab of bullet proof glass just behind the perspex, to give him some chance of surviving those German shells.
Actually a lot of gunners removed the central Perspex completely for a better view. At night the ability to see an incoming fighter meant that ranges were pretty short and thus the higher rate of fire of 4x.303 was seen as the best option.
