If you need to consult an expert find a lawyer. You local law enforcement are not necessarily experts on the law especially when it comes to the requirements for buying and selling firearms.
The Attorney General does not provide legal advice to citizens. In some states they do have opinions, drafted at the behest of a legislator or other member of government, that you can read.
The best option is to look up and read the statutes yourself. In many instances they are very clear. One thing to remember that what is not prohibited is permitted. So don't search statutes looking for them to say hat is permissible. Many people ask "where does it say I can do this" which is the wrong question. The internal revenue code is an exception to this general rule.