Although Sommer himself didn't add to his tally that day, Heinz Knoke and his pilots of sister-squadron 5./JG 11 had a degree of success by air-to-air bombing - dropping bombs into the middle of the bomber formations, primed on a short time-delay fuse, to break up and scatter the formation to make individual aircraft more vulnerable. Sommer did score a B-24 victory (his 4th overall) on the 14 May raid (Mission #56 on the submarine pens at Kiel), and his 5th a week later (a B-17 over Wilhelmshaven). About this time, II./JG 11 was re-equipping with Bf109G-6 'gunboats', carrying a pair of underwing 30mm cannons for a far-heavier punch. Now an experienced pilot against the "Viermots" Sommer's tally steadily rose and he scored a victory on most of the American raids in 1943. The odds were now stacking up against the American bombers, still without fighter cover over a good third of their mission, and with increasing numbers of Luftwaffe fighters drawn into Reich Defence. For example, on 13 June, where Sommer scored his 7th victory, the Mission #62 on Kiel lost a catastrophic 22 bombers out of 60 sent. Desperate to provide any sort of fighter cover, the Allies were trying to develop jettisonable fuel-tanks on their P-47D Thunderbolts to give them extra range. The last week of July was designated by the Allies for Operation "Gomorrah" - a 6-day round-the-clock pounding of the Reich by the Americans by day and the British by night (including the devastating Hamburg fire-raid of 27 July). Sommer shot down 3 bombers that week, taking his tally now to 11 victories. Missing the carnage of the combined Schweinfurt/Regensburg raids (#84) in August, Sommer's next victory was a B-17 on 27 September. This raid marked the operational debut of the long-range P-47s, now finally able to escort the bombers well into the Reich, and despite Sommer's success, II./JG 11 took its heaviest losses to date. Reflecting the change in the airwar over the Reich, Sommer's three victories (15-17v.) in December 1943 were all P-47 escort fighters. Another aspect was the vast increase in numbers - his 18th victory, a B-17, was one of 650 bombers sent on Mission #182 to bomb the aircraft factories in the Brunswick area.