It is still common in America (not MD) to go to flea markets and yard sales and see long guns for sale. While it isn't legal for someone from out of state to make such a purchase without going through an FFL, I'll bet you a doughnut it happens every day. I've never seen a sale at a fleamarket where anyone asks to see ID. And if you want my humble opinion... that is how it should be.
Yep, I found a rifle I liked for a really inexpensive price, last month. Went to a local FFL to make the transfer and came back from Ohio with a new (to me) rifle.