Complex sentence: The Soviets then set about developing a larger gun to mount in the T-34 chassis, and produced the SU-100, one of the best tank destroyers of the war, which had enough firepower to deal with the heaviest of German tanks.
Split into simpler sentences: The Soviets then set about developing a larger gun to mount in the T-34 chassis, and produced the SU-100, one of the best tank destroyers of the war. The SU-100 had enough firepower to deal with the heaviest of German tanks.