Let's say you replaced the copper alloy case with an identical case made of tin-silver-copper alloy, plated to be the same colour. The copper-alloy case normally seals the chamber of the gun, preventing gases from escaping during firing, and normally slips free from the chamber when ejected. If you fire a gun loaded with the new case, it will melt to the sides of the chamber and squirt into the receiver, making it impossible to load new ammunition. You'd need a good machine shop to render the gun usable again.
Next, replace the lead bullet with a mixture of tungsten grit, iron oxide, and powdered aluminum, held together with a plastic binder. Plate it with a layer of lead. It will weight the same as a regular bullet. However, when you fire the gun, the bullet will ignite and give off massive amounts of heat. The case will melt to the sides of the chamber. Molten iron will ooze down the length of the barrel, clogging it. The tungsten grit (in addition to making the bullet weigh the same), will also make it extremely difficult to just drill out the barrel. You'll ruin your drill bit if you try.
Finally, replace the chemical propellant with something non-explosive but annoying, like ground pepper. You could use a chemical irritant like CS, but that's too nasty. Have a thin line of primercord run from the primer to the bullet, passing through the pepper. When the gun is fired, the bullet ignites, and the heat of the molten metal causes pepper fumes to burst through the melted case and squirt out of the receiver. Whoever fired the gun involuntarily drops it, both keeping them from getting burned, and keeping them from trying to pry out the sizzling bullet before it destroys the barrel.
Now, sell these to police departments and the military. They can then make attempts to contaminate the ammunition supply chain of opponents. Leave a case of fake ammunition unguarded and let it get stolen, or bribe someone to sneak it into the opponent's supplies. Some guns will be destroyed by this. However, everyone else with a gun will then become paranoid about their ammunition. The fake ammunition looks, weighs, and feels the same, and even appears the same under x-ray and handheld XRF analysis. You'd have to cut into each round to check, or else use higher-powered XRF equipment (which isn't easily field-portable). This drives up the expense and inconvenience of the opponents. More importantly, it alters the behaviour of the opponents - each verified-good round is precious, and each shot fired risks destroying a weapon, so they conserve ammunition and do less shooting.
I could hand-make these for under $100 per round, or about $10 if I invested in automated machinery.
EDIT: No, there is nothing about arming bears in the Charter. http://laws-lois.justice.gc.ca/eng/Const/page-15.html