One other possibility -- if "tracking close to the thumbhole" means close to the right side instead of to the left side, he could be a full roller with a ball drilled for a 3/4 roller. Again, if he has a savvy driller this won't be the case. Of course, there's always the possibility the thumping he's hearing is actually the finger holes. Then, he probably has the pin out of the safe zone and is catching the finger holes on the last couple of flare rings. -- JohnP