Sad sad day when a human being - and a gun/tool-user no less - is defeated by a tin can.
(1) Screwdriver, Flat blade, Large
(1) Hammer, Any
(1) Pliers, Channel-Locks
Start near the upper bead, near a corner. Aiming away from the ammo contained inside, drive the screwdriver into and through the metal, and preferable through the outer sidewall.
Taking care to avoid mauling the ammo, use the leverage inherent to the Screwdriver, Flat blade, Large, and work it back and forth within the puncture until you have torn and raised a portion of the sheetmetal.
Withdraw the Screwdriver, Flat blade, Large and using the Pliers, Channel-Locks firmly grasp the protruding bit of metal and again with the leverage granted by this particular tool, commence winding said metal around the head of the pliers, tearing / enlarging the opening in the container as you go.
Once you've made the hole large enough, extract your prize.
/and before you make another bulk ammo purchase, spent the money on a basic set of tools, or turn in your Man card.