what does the "z" Mean

[Son]

Where are the Australians when you need them...............?

this one is still sorting out the files recovered from a computer change out.... I'll dig through my HT "H" pics and see if I can find another with the mark....

Ok, just checked pics of the "H" on nearly 20 more Lithgow snipers, none of them have the little z mark on them....

It may remain a mystery