i cleaned my chambers 16 guage with the kean bore lead removeal pads.. it kept comming out black after many pathcs on a wire brush with the stuff, and i feared it was removeing metal from the bore.. the next time out i shot ball.. it shot low which concerned me... i use alot of lead shot, knickle plated shot, and bismuth.. ive never found anything that removes bismuth. i didnt think much about it untill i got home and noticed my groups were almost half of what they had been in the past.. any one had good or bad experiences with kleen bore lead removal pads?? dave.