I'm pretty sure Deng doesn't get the bolts made bespoke for him. He probably get's them from one of the hundreds of bolt/cold forging manufacturers there are in China which would be rolled off off the production line in huge huge quantities. I would expect the manufacturer to produce some sort of quality control. I wouldn't be sure if Deng does his own tests, but even if he does, i'd say it was unlikely he would find a bolt out of tolerance, mainly because of the high quantities he must buy and the fact the manufacturer produces their own tests. So finding one bolt out of tolerance like you have pretty much means you're unlucky, because as a manufacturer it would be daft to check every single bolt, it's likely a guy on the production line will check one every 20-100 who knows, it depends how frequent the bolts tend to go out of tolerance and what sort of quality control measures they have. Phil.