Lancasters and 0.50 Cal Machine Guns

[forget]

Late in the war, the Lancaster's lack of defensive armament finally began to be corrected. Aircraft began to arrive with two 0.50 Cal. machine guns located in both the Rear and Mid-Upper turret positions. Although, the 0.50 caliber had a far greater range and more destructive hitting force than that of the 0.303, it still did not equal the German 20mm (0.75") cannons which were installed in most night-fighter aircraft.

http://www.ian.com.au/contact/lancaster5.htm