(1965) Half Dollar Pattern - RB-4505, INCO

Coin Details

Description

INCO experimental clad half dollar RB-4505, the second composition variant in the 1965 half dollar testing series. This piece tests a different alloy formulation from RB-4500, adjusting the nickel content or copper core specifications for the half dollar's larger planchet. The half dollar denomination presented distinctive metallurgical challenges for the clad concept: its greater diameter (30.6mm versus 24.3mm for the quarter) meant more surface area where color discrepancies could be detected, and its thicker cross-section altered the electromagnetic profile of the clad sandwich relative to the smaller denominations. INCO's engineers needed to determine whether the same cladding alloy used for dimes and quarters would perform satisfactorily at the half dollar scale, or whether modifications to the composition or layer thicknesses would be necessary. RB-4505 represents one data point in this investigation, struck on Kennedy half dollar dies at the Medallic Art Company to produce a fully realized test coin. Although the half dollar would not adopt clad composition until 1971, the 1965 experimental data proved essential in ensuring a smooth transition when that change eventually occurred.

Rarity Notes

R-7 to R-8. Very few specimens documented. The half dollar experiments in the INCO program consistently produced fewer varieties and lower quantities than the quarter experiments.

Cross References

Research Blank RB-4505 (Gould/INCO experimental series)