If you just want to play around a little, here's what you do.
1. Drop about 60 grains of powder down the barrel.
2. Ball up two sheets of toilet paper and ram it home on top of the powder. Pack it good and tight.
3. Drop about a 1/2 ounce loadof birdshot on top of the wad(number 8 or 7 & 1/2 works best).
4. Ball up 1/2 sheet of toilet paper and ram that down on top of the shot.Gently pack it tight.
5. Light her off!
I guarantee you this will kill a mouse at 15 feet.
Try patterning this load on a large sheet of cardboard at 10 yards, and let us know yourresults. The pattern out of my 50 Cal. New Englander is about 2 feet, with lots of holes.
One more thing. DO NOT shoot this load in a fire hazard area. Those toilet paper wads will smolder.