Carson City Dollars, among the provisions of the omnibus Mint Act of February 12, 1873 was one attempting to introduce metric weights for our national coinage. The nickel 5 cent coins were already supposed to weigh 5 gms. apiece (though in practice they varied enough to be useless as weight standards); henceforth the dime, quarter dollar, and half dollar were to weigh, respectively, 2.5, 6.25, and 12.5 gms. each. This provision hardly merits praise. Mint tolerances were broad enough on all denominations that the coins could not be safely used as weights (let alone legally), even if there was any reason at the time to use metric weights outside a laboratory. The new weights differed little enough from the old that beyond doubt planchets made before the new standard could have been used and many doubtless were: 38.58 +-1.5 grs. completely overlaps 38.4 +- 0.5. There is no foolproof way to distinguish new and old planchets, and no way to identify coins struck on obsolete blanks. Over 100 years after this act of Congress, the USA still lags behind the rest of the civilized world in introducing metric weights and measures; and though our silver coins had metric weights 1873 - 1964, this feature had no discernible effect on public awareness of the metric system.
For reasons unknown, the new coins were given a distinguishing mark: a reappearance of arrows at dates. Older issues were theoretically to remain current, though the incomplete records indicate that many pieces without arrows were melted down beginning July 10, 1873. These included silver from both San Francisco and Carson City; and the Philadelphia Mint also melted proofs of 1871 - 1873 without arrows in all denominations, as well as unsold 2 cent, silver 3 cent and half dimes, proofs and business strikes. These mass melting possibly account for the rarity of earlier Carson City Coins.
Dimes with arrows at date have long been prized as type coins, and some dealers long since began promoting them as alleged rarities, which fact is evidence less of scarcity than of cupidity. Quantities made were ample in Philadelphia, moderately small in San Francisco, and really small only in Carson City : this last from official orders restricting coinage to amounts well below capacity. Enough survive from the 5,327,700 Philadelphia business strikes and 1,500 proofs that the coins are always available for a price. The 695,000 S mints pose no sever problems except in mint state, in which condition both dates are very scarce.
On the other hand, the Carson
City issues (1873 Arrows [18,791] and 1874 [10,817] are both
rare, only a tiny fraction of 1% surviving in all grades; mint
state specimens are prohibitively rare, and the 1874 CC is of
extreme rarity in any condition: Newcomb said all six known
were from "circulation."
Some 500 proof sets of silver coins with arrows were struck in 1873, with the trade dollar included; there were extras of some denominations including possibly 300 more dimes. Collectors routinely broke up these sets in order to add the dimes to their date runs of the denomination, and similarly with the other denominations. This accounts for the rarity of original sets.
However, most collectors interested in pre-1936 proof sets have been content with assembled sets. These can usually be identified by different kinds of cleaning on individual specimens.
Arrow positions vary on both 1873 and 1874. However, whether higher or lower, arrow points on 1873 are level, whereas they point up on 1874. Claims of large and small arrows for either date remain unverified. The new metric weights continued for almost a century, but their importance to the Mint has consited solely in a multiplicity of decimal points in the operations of strip rolling, planchet cutting, and planchet weighing. They have remained as another instance of government tokenism.