The Australians had been allowed to use captured Italian guns, unlike the British artillerymen. The 24th Brigade had two battalions, the 2/28th and the 2/43rd. The 2/28th Battalion had 11 guns that they used in the anti-tank role. Presumably, these were the Italian 47mm guns. By 1 May 1941, they had knocked out nine enemy vehicles. On 5 May 1941, the 2/43rd Battalion had nine Italian guns. They had field and medium guns from 75mm to 149mm. They called these captured guns "bush artillery". They had an advantage over the British field artillery units in that they had a virtually unlimited supply of captured ammunition at Tobruk. The guns often had problems, such as lacking sights, but some of these were solved either by cannibalizing or by stealing parts from the Italians during the night.
The guns were originally manned by whomever was available, but the Australians eventually were more careful about the crew compositions and they were often able to supply officers with some anti-tank or mortar experience to command the bush guns.
Over time, the enemy was less intent on land attacks against Tobruk. Instead, they concentrated on air attacks on ships and the harbor area. There were 734 sorties against Tobruk during May 1941. They forced the British to abandon using hospital ships to evacuate wounded. Instead, they had to use destroyers. The air attacks on ships caused the loss of a minesweeper on 6 May. Six days later, the gunboat Ladybird was sunk in the harbor.
At the end of April, all combat aircraft were withdrawn from Tobruk. The defenders of Tobruk desperately needed air reconnaissance to gather intelligence about the besieging forces, but there were simply not enough aircraft available to make risking them at Tobruk a possibility. After communicating with General Beirsford-Peirse, General Morshead wrote to General Blamey, the senior Australian officer in the Middle East. Morshead wrote that the sort of reconnaissance by Hurricanes that was available was very unsatisfactory. What they needed was photographic reconnaissance. This is based on the account in Vol.III of the Australian Official History.