My Mk 14 Spitfire had two 20mm Hispanos and two .5 Brownings fitted..

Rather oddly the F8F Bearcat , which was to replace the F6F Hellcat, went back from 6x0.5 guns to only 4x0.5 guns

The F8F Bearcat was designed as an interceptor where rate of climb was an overarching requirement, for weight saving armament was stipulated as 4 X .50 cal and ammunition load was reduced by 25% compared to the F6F, weight savings were also found in armour protection. Test pilots of the prototype requested installation of six guns, but never occurred, though the .50 cal were latter changed to 4 X 20mm cannons. The four .50 were deemed to be adequate against the lightly constructed opposition, who also lacked armour protection and self sealing tanks. Never saw combat, though a squadron was enroute to the zone when Japan surrendered.