An explanation: 1772 Mo FM versus 1772 Mo MF               
                 1773 Mo FM versus inverted FM


    All 1772 and some 1773 Portrait 8 Reales have inverted initials (KM 106.1).

    KM  is unclear when it desecribes the "inverted MF error"

      The "error" KM refers to is substituting "MF" for ""FM".
 The inversion may be a second  "error", but this is the style for all 1772 pieces.

     These illustrations should clarify.


      Is the rarity of the 1772 Mo MF overrated? See below.
 
1772 Mo FM  KM 106.1

1772 Mo MF KM 106.1
1773 Mo FM "inverted" KM 106.1
1773 Mo FM "normal" KM 106.2

      Although my experience is limited to the two pieces I had purchased, I suspect that the rarity of the 1772 MF piece may have been exaggerated by misidentification.

       1772 8 Reales  (both varieties) are not commonly offered.  
 
      I had been looking for quite some time for both the 1772 FM and the 1772 MF.
I had purchased the 1772 "MF" 8 Reales first. It was identified as  "FM".

      It was only after I purchased the 1772  "FM" piece a year or two later from  a dealer specializing in Mexican coins that I was fairly certain that the first piece was "MF".

    Maybe I was just lucky,

    My feeling is that ALL 1772 portrait eight reales are rare, so most dealers and collectors   who haven't seen both varities read the letters from left to right in continuity with 8 R of the legend  and misidentify the MF as FM.