The enormous mintage of 1964-dated nickels from the Denver Mint was the product of a date freeze imposed by Congress. In fact, more than two-thirds of 1964-D nickels were actually coined during 1965.
With such a large number produced, one would expect a significant population of full step pieces, but the opposite is true. These nickels were a rush job intended to address a nationwide coin shortage, and very little care was used. Weak strikes from worn dies are the rule, though gems do exist if one overlooks full details as a criterion.
This issue offers one of the better RPM varieties in the Jefferson series, as well as several lesser ones. The few doubled-dies known for 1964-D are of little interest to anyone but variety specialists