The only place I can gain access to the beach at Kiawah is at the county park at the south end of the island.
I have tried walking for a couple hours up the beach and detecting back and found very little.
I hit the south end of the island a couple times each year in Nov and usually dig up some clad I have found a couple 14k rings down there but my trip early in Nov only wielded some clad in one small area Lots of flat beach with deep sand so targets can be difficult to find
Good Luck