I have 3 tins of the hunters in .177 bought in 2006 and 2007 and they are very light. Not as listed.
I weighed them with a SHIMADZU UW220H lab scale at my job (very expensive scale). This is what I got in grams and cal. to grain. This scale is in closed so air will not affect the total, and I zeroed it for each pellet.
Gamo Hunter 8.4gr (.177)