The way to do it is the 30mm on the Hog has a longer range than the guns on the BMP/Shilka. So you have to fire your burst before entering the tgts umbrella and break away. So fire from further away and break off, also use the terrain to mask your ingress and egress if there is some available.

BTW CBU105s/97s are the best weapon against tanks you can easily take out 9 with just 2 CBU97s. The idea though is to drop the CBU in the middle of the convoy whilst flying towards the centre rather than approaching from the rear or front of the convoy. Because of the way the spread pattern of the CBUs skeets from my experience most kills are gained by using this approach.