Re: Only cracking I have done is
Get a settling torch. Cut a hole with it in the top of the safe. Pump a load of water into it until it's full. Put a charge in it to cause a small explosion. Set it off. The pressure inside and shock wave from the water will blow the doors off.*
Obviously only useful if full of gold or silver. Money would kinda get wet.
*Yes I've stolen that from The Score (sorry if that now ruins the movie. Still a great movie and still not fully ruined the plot for you).