- 5 June
- Coastal guns at a range of 25,000 m. Eight shells fired.
- Fort Stalin. Six shells fired.
- 6 June
- Fort Molotov. Seven shells fired.
- "White Cliff" aka "Ammunition Mountion": an undersea ammunition magazine in Severnaya ("Northern") Bay. The magazine was sited 30 meters under the sea with at least 10 meters of concrete protection. After nine shells were fired, the magazine was ruined and one of the boats in the bay sunk.[3]
- 7 June
- Firing in support of an infantry attack on Sudwestspitze, an outlying fortification. Seven shells fired.
- 11 June
- Fort Siberia. Five shells fired.
- 17 June
- Fort Maxim Gorki and its coastal battery. Five shells fired.
By the end of the siege on 4 July the city of
Sevastopol lay in ruins, and 30,000 tons of artillery ammunition had been fired. Gustav had fired 48 rounds and worn out its original barrel, which had already fired around 250 rounds during testing and development. The gun was fitted with the spare barrel and the original was sent back to Krupp's factory in
Essen for relining.
The gun was then dismantled and moved to the northern part of the eastern front, where an attack was planned on
Leningrad. The gun was placed some 30 km from the city near the railway station of Taizy. The gun was fully operational when the attack was cancelled. The gun then spent the winter of 1942/43 near Leningrad.