Why Are There So Few 1873-CC No Arrow Dimes?

The PCGS Pop figures are wrong, the 1873-CC no arrows dime is still unique. I believe two of the three are the same coin (cracked and resubmitted) and the third one was the result of an entry error that has never been corrected.

As to why it is so rare, the weights of the silver coins were increased in 1873 (hence the addition of the arrows) by the Act of Feb 12th 1873. The act, coming so early in the year, cut off the no arrows coins before very many had been made, And you can see from the mintages of the all of the 1871 - 1874 dimes that this denomination just wasn't called for very much so very very few 1873 no arrows dimes were struck before the law passed, and once it did they could not be issued becuse they were not of legal weight. So officially none of them were actually issued. The one unique coin was one of the coins retained for the Trial of the Pyx, the annual assay of the nations coinage. That dime was not selected for destruction in the assay though, and it was purchased for face value by one of the Assay Commission members once the assays were completed.