Roman lead slingshot

[slinger]

How common is Roman lead slingshot?
I have seen descriptions of some of it as 'having been used,' yet how can one tell if it was used? Just because it is broken? I have a piece that has a good portion missing. Why couldn't this just be a manufacturing defect, reject piece etc.? It is not from the site of a -known- battle although it was found with several other lead slingshot pieces.
Also, is there a website that has a listing of the markings found on lead slingshot, to identify where they are from? This would be useful.
I would really like to know as much about Roman lead slingshot as possible, but most of what I am finding online are sellers on Ebay offering what are probably fakes for sale.

[tommy303]

Typically a defective casting would simply be tossed back into the melting pot and reused. It would be difficult at times to know if a shot had actually been used unless it hit something hard enough to flatten or deform it somewhat or leave some other tell tale mark of an impact.