No need to use lead shot; there is a cheaper alternative.
In a 44 Magnum or 45 Colt, use 1 grain of Bullseye. Make a punch out of a discarded case by sharpening the case mouth, and then use this to make wads out of scrap cardboard, such as from a pizza box, etc. Next put one of these wads over the powder, and seat with a 3/8" wooden dowel. Now fill the case with dry rice or grits, and then put another cardboard wad over this. If you have a good tight fit, and if you aren't going to carry them around, they can be used just as-is. However, if you are going to be carrying them for any length of time, you should glue the top wad to the case with a ring of super glue, or some other glue or sealant.
The best part of not using any lead shot is that the load will not do any damage to windows or paint on nearby buildings if the distance is more than only a few feet away.
Have fun.