Ron Guth: Judd 160 and Judd 161 are from identical dies, struck in copper and bronze, respectively.
Judd (7th edition) diffrentiates the two by weight: 100 grains for the copper; 96 grains for the bronze. However, Pollock (1994), lists a range of weights from 90.9 to 100 grains, plus two additional pieces with weights of 113.4 and 113.9 grains, presuming that the two heaviest weight pieces were restrikes.
PCGS recommends non-destructive analysis to determine the actual composition, because it is impossible to differentiate between copper and bronze by sight.
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