Interesting question. I'm not sure a wood tip is really desirable on a cob pipe. I definitely don't think soft wood is a good idea. Both of the working pipes I have use some kind of acrylic tip. (They are cheap models, though.) I am guessing there are a few reasons for that. IMHO, it would probably be less costly in the long run to invest in a briar pipe or two, than to re-fit your current pipe.