This is an example of a professor, steeped in scholasticism, dispensing his unsupported version of knowledge to the naive and unsuspecting. The damage that he is creating at this level of education is possuibly irreparable. Here we have an eager mind, paying good money for an education, only to get half or non-truths pumped into him (her), to gratify a professor's ego or misguided philosophy. What most all the above have told you is the real truth. Only FOOLS would stand a table or walk a gunshow with guns with filed numbers, illegal machineguns, etc, and expect to walk freely for long. Many legit gunowners attending a gunshow would not even tolerate a fool like that, and might turn them in just to keep the reputation of the gunshow intact. The police (usually working for the event holder)even INSPECT carried in guns at the gunshows here in Ohio, and would most likely spot a filed serial number gun immediately. I guess we need to be vigilant of our educators, even at the college level, and challenge them accordingly, or report them to THEIR bosses. Constant vigilance and challenging authority is what makes this country FREE.