Armourers work on the barrels of 0-303in Browning machine-guns in the wings of a Hawker Hurricane, probably during the Battle of France. The Hurricane was fitted with eight Brownings, Air Ministry Specification F.5/34 having stipulated six or eight 0.303in Browning machine-guns, each of 300 rounds, to give 15sec of fire.

The North American Mustang I was introduced into RAF service in early 1942 and was fitted with a mixture of 0-303in and 0-50in machine-guns; the lower engine cowling accommodated a pair of 0-50in Brownings which fired through the propeller arc, and each wing housed one 0-50in and two 0-303in machine-guns.

In common with its RAF fighter and bomber contemporaries, the Fairey Battle light bomber was fitted with 0-303in-calibre machine-guns - a fixed forward-firing Browning in the starboard wing and a Vickers K on a Fairey high-speed mounting in the rear of the cockpit, which, curiously, in this case is fitted with a 0-303in Lewis gun.
The air gunner in a Fairey Battle wields his Lewis for Flight's cameraman. The windscreen folds down to complete the line of the cockpit enclosure.
The Battle normally carried a crew of three, 1,000lb of bombs, a forward firing Browning .303 and a Vickers K .303 mounted in the rear cockpit.

Avro Lancaster I W4154 of No 1662 Heavy Conversion Unit, based at RAF Blyton in Lincolnshire (and thus close to the Rose factory), is seen here with a Rose tail turret in 1944. Although the latter showed much promise in increasing the defensive firepower of the RAF’s bombers, only 227 examples of the twin-0-50in turret were built.

The Rose Bros turret assembly shop at the company’s factory at Gainsborough in Lincolnshire circa 1944. The production line incorporated eight stations, each of two stages, and work around the clock resulted in the completion of a turret in as little as 7hr. The production version was designated the Rose Type R Mk I turret.

The Rose turret was designed with a great deal of input from Gp Capt A.E. Rice of Bomber Command’s No 1 Group, and incorporated a pair of 0-50in machine-guns, as seen here. The Brownings were set wide apart, which not only allowed for easy servicing but also enabled the gunner to bale out directly through the generous clear-vision panel.
The Rose turret - an example of which is shown here at the company's works - was large enough to accommodate two gunners, although there was, of course, no operational requirement for this.

Lancaster Mk VII NX791 of No 617 Sqn in 1945. The Mk VII was fitted with a Glenn Martin Type 250 dorsal turret armed with two 0-50in Browning machine-guns, as was the Frazer-Nash FN82 tail turret. Had the war lasted another year, it is likely the Martin 250 would have replaced the 0-303in turrets of all the RAF’s heavy bombers.

Air Ministry Specification F.9/35 called for a two-seat “Day and Night Fighter” fitted with a “midships turret armament”, resulting in the Boulton Paul Defiant, the prototype of which, K8310, is seen here fitted with the company’s own Type A powered turret design, accommodating four 0-303in Browning machine-guns. No forward-firing armament was fitted.

By the time Air Ministry Specification F.37/35 was issued in 1935, it had been recognised that striking power superior to the eight-gun armament specified in F.5/34 was worth investigating. This led ultimately to the Westland Whirlwind, fitted with four fixed Hispano 20mm cannon concentrated in the nose, as seen here.

Along with their fighter counterparts, the RAF’s bombers were also fitted with 0-303in machine-guns. After early wartime operations revealed that the Vickers Wellington had inadequate defensive firepower, the Mk III was fitted with eight 0-303in guns, the new Frazer-Nash FN20 tail turret incorporating four 0-303ins instead of just two.

Four 0-303in Brownings in an aft-facing Boulton Paul Type A electrically operated dorsal turret fitted to an Armstrong Whitworth Albemarle. The Albemarle’s dorsal turret was offset slightly to port to allow space for a passageway through to the rear fuselage, and the fairing forward of the turret retracted automatically when the turret was trained to fire forwards. The Albemarle saw only very limited service.