Praxis: "From Ingot to Target: A Cast Bullet Guide for Handgunners."

An excellent resource. You might want to download this own and print it out.

While reading the chapter on bullet metallurgy I encountered this observation, of which I was skeptical:

Recovered range scrap varies from range to range, depending on the nature of the shooting at that particular locale, but it commonly runs fairly soft (in the BHN range of 8 or so) as a result of all the .22 Long Rifle and swaged .38 wadcutter ammo deposited in with the jacketed and hardcast bullets.

I should not have doubted. Yesterday I went out to the Talladega National Forest, Talladega Division, over near Mount Cheaha, to verify some finer points of geography for the final chapter of Absolved and stopped by the Shepherd Branch firing range to see if there was anything (boxes, brass, lead) worth picking up. I always try to make the gas money count. Anyway, I spent about an hour on the range, which was empty of shooters and rangers, and got a thin yield of about eight and a half pounds of range scrap bullets washed to the surface by recent rains. (I don't dig out backstops for folks take a particularly dim view of that.)

After washing and sorting between cast and jacketed (which is advantageous because the jacketed stuff is very soft compared to the cast), the percentage of cast to jacketed was significantly higher than other ranges whose backstops I routinely mine. Go figure. The fellow knows what he's talking about.

Cooking down range scrap.

Here's a description from the Cast Boolits forum on the experiences of others with range scrap.