Doing some searching for a Buck 110 50th, and have come up with 3 different versions.
One is general sale 50th with plaque in the scales, then there is a Federal one ,which is a limited run of the original 110 with 3 pins
and then there is a limited addition one 0-2000 with etched blade and scales, Go figure
Further searching has found a 4th being a finger groove 110 50th
http://www.ebay.com.au/itm/BU7687-Bu...item4864dfc097
http://www.ebay.com.au/itm/BUCK-KNIF...item56636c146d
http://www.ebay.com.au/itm/BUCK-KNIF...item48642ab498
http://www.ebay.com.au/itm/Buck-110-...item43c7b08287