Most cops don't know $h!t about guns, or gun laws. Knife laws either for that matter. They get paid to enforce laws that they have no clue about. I found this out after getting a gun and some knives confiscated, each on seperate occasions.
This is true, many cops have no clue as to the gun laws in their jurisdiction. I do not ENTIRELY blame the individual Officers though. 1) incomplete training and lack of communication to officers of laws and changes in laws is part of the problem but also, WE are only concerned with one set of laws, the ones pertaining to fire arms, Cops are supposed to know about Traffic laws, drug laws, search and seizure laws, rules of evidence, property laws etc etc.
Often, if I've got enough pockets, I will carry a copy of the NH gun laws, if I'm ever confronted over the matter the officer does not have to just take my word, He may not believe me, but it raises a question in his mind and gives him an incentive to ask some one before he does something that gets Laconia into another losing lawsuit.