289475
A pair of synchronised Vickers machine gun s fixed to the fuselage fired forwards through the propeller arc ; in addition the rear cockpit was fitted with a pair of Lewis gun s of the same calibre on a Scarff ring .
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Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
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