It wasn't a muskett. It was a stick with a big rubber band. 
When I was eight my dad made a slingshot using a 1/4 inch steel rod, a strip of rubber from a tire and a heavy piece of leather. You had to mount it because you couldn't pull it back with one hand. In our backyard my uncle had a pidgeon coop that used to attract rats. Standing on the small balcony outside his bedroom we spotted one coming out of the hole in the wall separating us from a neighbors junk yard. He put a steel ball bearing in the leather, pulled back and took aim. I watched as the rat's head exploded! Yuck!
