The 1916 McKinley memorial dollar struck in nickel. It was likely deliberately struck for profit as opposed to being a true die trial. This used to be J1802 in earlier editions of Judd. The coin is believed to be unique and has the following pedigree - Raymond 4/46, Curtis, Farouk, (described as silver P2060),Sloss-79 ANA, Superior 10/92, Heritage 3/99. An obverse die trial JA1916-1/P3551 is also known. Photo courtesy of Heritage.