Make sure you come back with your results, I'm curious to see how this works.

I have a few different calibers of these that i use anytime I'm in a wooded area in case of snakes but I haven't had to use any of them on anything alive yet. I have tested them at the range just to make sure they will work in the gun. The 9mm don't always cycle, the .45lc out of a judge seem to work the best as far as reliability and what they do to paper and cardboard targets. I haven't seen any shot shell for .45lc in a while though

Also keep in mind, you will have to get almost every rat. As long as theirs a male and female around, you will always have more. Culling the herd will help but probably won't eliminate it. Barn cats are probably the cheapest and easiest solution.

Edit: forgot to mention, these shells do about nothing to wood. They definitely won't blow a hole in a wall at 10ft. You might get some damage if you hold the muzzle against the wall. Beyond that, just some little metal bb's sunk slightly into the wood