I hear you, but a gunsmith can't possibly have experience on every gun out there. It is their knowledge of guns and their workings in general, along with the practical knowledge of experience, that allows a gunsmith to work on most guns, even though they may never have worked on a particular design. That is like asking an auto mechanic to know everything about every vehicle ever made (which is probably a similar variety and range compared to guns). A good mechanic may need to do some investigation and research on a particular vehicle or design, but if he or she is a good mechanic, that research will help to get the job done right, rather than driving a pin out that won't move, merely by hammering on it hard enough.