I've been using up my old lead shot for my 10 ga. 3 1/2" shells loaded with BB shot. I haven't lost a turkey yet and with the rate that I am going I'll run out of these shells in about another couple hundred years.
Now if I drag out my 12ga I'll use 3" mag shells with #2 lead shot which I have a lot of also.
From the books that I have read, there is a lot of importance in knowing every nook and cranny of your hunting territory as well as the animal that you are hunting. So scouting as much as possible, just walking the land, will give you a good idea of what's around the corner or what's on the other side of a hill. Which can be very beneficial.
Making your own maps of human and deer trails, and different types of foliage such as group of pines,...