Jaime Hernandez: In 1873 the Mint struck two different major varieties for the Shield Nickel. It struck an Open 3 and Closed 3 variety. The Open 3 variety shows the serifs on the 3 digit more spaced apart from one another, hence, referred to as the Open 3 variety. The Open 3 variety is the more common of the two varieties and some believe it is about 10 times more common than the Closed 3 date variety.
In Uncirculated grades, there are possibly about 500 examples remaining. In MS60 to MS63, there are probably about 300 - 350 examples in existence. Most uncirculated examples are in MS64 grade, with possibly about 150 examples known. In MS65, possibly about 50 examples survive. In MS66 grade, about 10 examples are known with none being finer.