Mayor Michael R. Bloomberg, a leading advocate of stricter gun control, said yesterday that there was nothing wrong with owning a gun for hunting. In fact, he said he even had one himself as a teenager. Mr. Bloomberg told listeners on his weekly radio program on WABC-AM that he participated in riflery at a Boy Scout camp, and that his parents later allowed him to own a rifle while he was growing up in Medford, Mass. "When I was 15 or so, I had a .22-caliber rifle, but I used it only at a range, and you know there's nothing...