Complex sentence: The weaponry was impressive, all concentrated in the nose, all built by Breda: a 20 mm gun with 110 rounds and four 12,7 mm heavy machine guns with 2,000 rounds.
Split into simpler sentences: The weaponry was impressive, all concentrated in the nose. A 20 mm Breda gun with 110 rounds and four 12,7 mm Breda heavy machine guns with 2,000 rounds.