Contrary to popular belief, South Carolina state law does not forbid the open carry of firearms.
Now, read on, because all is not as it seems. (And do not go strapping a pistol to your side for a stroll through Wal-Mart.)
What the law forbids is possession of a handgun unless you meet a long list of exceptions. That’s right: possession. The law doesn’t state how you can carry (or not) the handgun. It states you cannot have it unless you meet an enumerated exception. General open carry is not an enumerated exception for possession of a handgun. Some exceptions include hunting, being on your own property, and going to and from a range or gun shop. Where an exception does not limit how you can carry the gun then you could carry it openly when meeting that exception.
Notice that above we were talking about handguns. And handguns only. South Carolina state law specifically exempts rifles and shotguns from regulations on carry. Long guns you may carry in plain sight or concealed without violating state law. This is the true open carry that South Carolina allows.
Unfortunately, that is not the end of the story. Counties, and more likely cities, may further attempt to restrict the right to carry a firearm. Whether or not such laws would withstand a challenge under SC preemption law is another question.
So before you decide to take your AR to dinner, you better know your local laws! And remember, even if legal, you will likely receive attention, unwanted or not: So be an upstanding citizen.