One of the odd curiosities among the earliest U.S. coins are the Silver Plug Half Dollars and Dollars. These coins were the result of a strict adherence to the government-mandated technical specifications of the time - most notably, the weight of the coin. Neither underweight nor overweight coins were acceptable, but because of the technology used at the time, off-weight planchets appear to have been the norm. To correct underweight planchets, a hole was drilled in the center of the planchet and a silver plug was inserted to bring the planchet to the proper weight. The planchet was laid in the press, with the silver plug placed in the hole, the coin was struck, and the plug was flattened and spread out to fill the hole. In many cases, the presence of the plug can be detected by a thin seam around some, most, or all of the circumference of the plug on one or both sides of the coin.
To correct overweight planchets, a metal file was used to scrape away excess metal. This resulted in what are known today as "adjustment marks" -- marks in the planchet that were not obliterated in the striking process. To the neophyte, these appear as scratches in the coin; to the knowledgeable numismatist, they are a normal part of the striking process.
In rare instances, certain coins will have both a silver plug AND adjustment marks, indicating a correction of both an underweight then an overweight planchet.
The 1795 BB-18 Silver Dollar is one of the most available of the Silver Plug Dollars, but it should be noted that all are rare. This variety includes the finest of all the Silver Plug Dollars -- the PCGS MS65+ example from the D. Brent Pogue Collection.
William Strickland Collection - Charles Winn (husband of Priscilla Strickland, son-in-law and cousin of William Strickland), Rowland Winn, 1st Baron St. Oswald of Nostell - Rowland Winn, 2nd Baron St. Oswald of Nostell - Rowland George Winn, 3rd Baron St. Oswald of Nostell - Rowland Denys Guy Winn, Major the Lord St. Oswald, M.C. - Christie, Manson, and Woods 10/1964:141 - Spink & Son, Ltd. - Lester Merkin 10/1973:451 - Dr. Herbert Ketterman, sold privately - James A. "Jimmy" Hayes Collection - Stack's 4/1983:1220 - RARCOA, sold privately in 9/1987 - D. Brent Pogue Collection - Stack's/Bowers & Sotheby's 9/2015:2043, $705,000
Richard Winsor Collection - S.H. & H. Chapman 12/1895:388 - David S. Wilson Collection - S.H. Chapman3/1907:366 - T. James Clarke Collection - New Netherlands 11/1956:612 - Jacque C. (Mrs. Alfred) Ostheimer Collection - Lester Merkin 9/1968:230 - Robert W. Barker Collection - Stack's 10/1986:102, $14,300 - Hain Family Collection - Stack's 1/2002:1500, $161,000 - D. Brent Pogue Collection - Stack's/Bowers & Sotheby's 9/2015:2044, $282,000