I haven't worn out any cobs lately but then I just recently returned to the pipe world (last fall). The last one that I wore out was a MM, not sure which one but I think it may have been a Legend. It burned out where the stem joins the bowl, not in the bottom where I expected it. I smoked that pipe for several years, can't remember how many exactly but I definitely got my money's worth out of it. Before it burned out, it started bulging in the middle of the bowl.