10 para 1868 from Serbia weight variation help

Hi to all ! I have a question about this coin.I know and all catalogs confirms thet this coin is 10.00 g weight,but i have found a lot of coins that have weight between 9.65 to 10.00 g so i checked other references like diameter,material,magnetism and details and can not find any fake preferences but weight.I have found this coins in both versions,in medal and coin alignment.I have spoke with some other people and they said that coins are genuine.I must say that coins was not worne or damaged to lose that mauch of weight.I also know that in old Serbian coin documents the coins in 1868 were strucked as 1 para is 1 g ,so is there anyone to help me and explain what is going on with this coins? Thank you! 

Mine is 9.65 grams in vf- grade, which is normal.

Hi and welcome!

My examples:
9.80g, rotated, first issue coin alignment
10.03g “normal", medal alignment

My 1879 is 10.18g.

I would say these are normal variations, although admittedly large(more than usual 5% of the time!). Legal weight is 10.00 indeed, these are well documented both from legal sources and numismatic sources.