And no words about indestructible gas mines? With plasma torch you can break steel doors, but not mine tunnels. And most explosives can "mine" only few tiles per boom (and you need to avoid booming the miner somehow). It is way too slow for 20 turns you have.
The best approach I figure out is just give a pickaxe to every uber and tear down this stupid bank to the last brick. (Another discussion topic: why Mining Laser is so crappy even in comparison to the Pickaxe?)
Don't you think that Bank Robbery mission is much more challenging then any other "B" missions?
You can mine with (regular) 85mm Cannon shells. Those are the explosives I used. Sure, they blow apart 1.5 tile deep in dirt, but you can shoot a few every turn. They aren't good against metal walls and doors though.
This is also how I tend to break into the prison to rescue Reynerd.
I did not remember there were mines.