In the state of South Carolina you would be breaking no law. Open carry of a long gun, or concealed carry if you could figure out how to do it, is entirely legal. Those of us who live in far less populated areas do it all the time with no problem. That being said, in less rural/more populated areas you could probably expect at a minimum to be harassed by your uneducated local LEO and at worst be caged on some trumped up charge. I understand that "going to the terror of the public" is/was popular. I suppose they may be "in fear for their life" and shoot you as well giving them reason to shoot you.
Now, before any of the local know-it-alls tell me I'm wrong, I'm willing to engage in intelligent conversation. But any responses had better start with a citation of whatever SC laws make it illegal to do so. Carry on.