For your consideration is a Civil War era Cavalry picket pin. It looks to be a non-dug specimen retaining a good deal of original black paint. Figure 8 swivel complete and in working order.
The top looks to have an applied well hammered sacrificial cap on top. It is 19 5/8 inches long. The diameter of the cap is 1 1/8 inches and the swivel is 4 5/8 wide.