I purchased a 1993 Harrah's 7 dollar strike with a mint mark of NCM Nev. coin mint ... I realize that weights vary & the weight of the 7 dollar is is approx. .65 troy oz's , I weighed my strike & it is .79 (my scales are fairly accurate ... is this cause to be concerned or grateful for the extra little bit of silver ( the strike is great.... looks,strike & reeded) .... thanks