wow, it let me log on!! the last time i got on, i made a quick post and it froze just after hitting the submit button......lets see this time.....
anywho, welcome to pondboss david u. i was involved w/ a major clean up at a local former air force base some years back. one of the projects was investigating and cleaning up the shooting and skeet range for redevelopment of the area. the skeet range was used from the late 1930's through the early 1990's.....i.e. about 60 yrs. over that time i am not sure how the composition of clay pigeons changed if any, i'm sure the EPA found early clay pigeons contained some potentially toxic stuff, and they are made differently today....but the clay pigeon debris was so thick at this site it formed a "geologic layer" over 10 feet deep. we pulled out and sampled some 10,000 cubic yards of dirt and analyzed for heavy metals and heavy carbon chain organic contaminants which could have potentially leached out of the debris field including PAHs, SVOCs, dioxins, etc......basically everything was clean and of extremely low environmental risk.......there's my input (long answer) to your (short) question
have fun