Until 1990, mintmarks were hand-punched into the dies. I could be wrong, but in this instance, the slight difference between the two may be due to the pressure of the strike when putting the mintmark on the die. Since many mintmarks are tapered a bit, a lighter strike would produce a thinner mintmark while a heavier strike would produce a fatter mintmark. Like I said, I could be wrong and this is just a guess. Chris
Absolutely. There's also the possibility of normal surface subsidence/wear during the die's lifetime - as the die ages, the mint mark will appear "smaller" because the punch letters are tapered. Another possible factor is die polishing during the life of the die, which would have a similar effect.
You also can go to Varietyvista.com as this site has mint mark styles used during different periods .
