Which way did the Beardmore S.B.3F's machine gun fire?

The Beardmore W.B.III was derived from the Sopwith Pup, which Beardmore was then building under licence, but it was specially adapted to operate from ships. It had a redesigned wing cellule, without stagger and with an additional set of inner struts that made it easier to fold for stowage. Those straight, parallel struts, unlike the staggered arrangement of the Pup, met the Navy's requirement for hand-foldable wings.

The prototype and the first 13 production W.B.IIIs had a folding main undercarriage and were known as the S.B.3F, for Sopwith-Beardmore 3 Folding. According to All-Aero, that first batch of around thirteen aircraft was later replaced by the revised S.B.3D variant.

All-Aero describes the armament as a single fixed, upward-firing .303 in (7.7 mm) Lewis machine gun, firing through a cutout in the upper wing. British Aviation – Projects to Production speaks of a .303 Lewis on a special mounting in front of the pilot's cockpit, firing through an opening in the centre section. Another specialist work, The British Fighter since 1912, by Peter Lewis, places it on the wing centre section, offset to starboard and angled slightly upward to fire over the propeller. The three descriptions agree: the gun fired forward, with a slight upward angle to clear the propeller arc.

Small numbers served aboard Royal Navy ships. All-Aero cites three: the aircraft carrier HMS Furious and the seaplane carriers HMS Nairana and HMS Pegasus.