Would you explain CO2 canisters (cartridges?) and fishing?
LOL - I was going to post this before, but didn't.
Okay...
Empty CO2 canisters work great for fishing.
Use a side cutting pliers to chop up a lead sinker in small enough pieces to shove inside the canister.
Fill the canister 2/3 to 3/4 full of black, or white powder. Don't fill it totally full, you want some space so the powder can expand before the metal reaches its stress fracturing point, and the gas has somewhere to expand to. Douse the cannon fuse with superglue as you are inserting it. Crimp the neck of the canister tightly shut with a pliers or channel lock, but don't pinch it so tightly that you pinch the fuse off. Apply a little more superglue.
Light it, toss it, and collect your dinner.

1. Cannon fuse burns underwater
2. Make sure there is no powder in the neck where you crimp - you only get one mistake.
This is especially important with white powder - it's very friction and impact sensitive.
3. Only do this if the water is at least 8' deep, unless you want to dodge shrapnel.
4. The lead shot in the bottom keeps the canister from floating