>>2033653https://www.ecfr (dot) gov/cgi-bin/retrieveECFR?gp=1&SID=23ed459fa10bd22433e6997e6bff4dbc&ty=HTML&h=L&mc=true&r=PART&n=pt43.2.3860
yeah, it's kinda hard to wrap your head around most things but this link should provide good guidance for USA rules and regulations. A bit part of it is just doing what you want and if caught you apologize, plead ignorance, and offer to put the material back from where you got it. That has got me out of a few tickets. Being said - if they find you twice in one spot be ready for the fine. Can think about it as a cost of the hobby