The first A-36A flew in Sept 1942, [they wanted to call it 'Apache', but the Brit's 'Mustang' stuck- The Mustangs, were in fact developed FOR Britain..] The A-36A's incorporating mods to strengthen it, and had special hydraulic dive-brakes to slow in high-angle dives. It had 2x.5's in each wing, 500 were ordered and first saw action over Pantelleria in June '43 with the 27th BG. They had a high attrition-rate, being vulnerable in pull-out and were known to disentegrate due to wing over-stress. They were eventually replaced by P-47's in early '44. - ALL that I've studied of the Mustang, it never had .303's, but .30's, .50's and 20mm's.