I decided to test if "Hydro-forming" could be a better way to do this. I have yet to destroy a can using this method. Fill the bottom half to the top with water. Using an unopened can insert it vertically. It will not go very far into the bottom can due to the water. Start to work the unopened can at a slight angle using a circular motion. This is similar to working a mortar and pestle. There will be small amounts of water that leak out when it is angled. This allows a deeper penetration each time water is removed. The can actually stretches when it goes from an angle back to vertical. The water provides lubrication which makes the movements easier.  Make sure to do similar motions completely around the circumference to get an evenly stretched can.