Here I am!
I haven't been able to find any study about the Fossombrone glans, and I have only the picture I've posted - at least those glans doesn't seem inscribed. But they're exposed at the Archaeological Museum of that town and I'll go there and take some pics as soon as possible. I'll even buy the Museum's catalogue; perhaps there will be more informations. In the meantime, I'll ask some teacher of my university, one of them is digging a Roman town near Fossombrone and perhaps he'd know something useful!
I believe that lead glans are a Greek invention, but take this as a mere supposition. The oldest date I've found for an Italian lead glan is the IVth Century - that glan has been found in Southern Emilia Romagna, ancient Etrurian territory, and it is known that Etrurians were the main trading partner of Greeks. But I absolutely don't know a thing about glans foundings in South Italy, which was Magna Grecia, nor I have any information about glans in Northen Italy - North from Emilia Romagna it was all Celtic territory, more or less. I just know that Venetian slingers fought against Piceni, but this lead us again in the Ist Century b.C., and it is unimportant.
The reason why I believe that Greeks imported lead glans in Italy is that, in a Greek temple in Puglia (South East Italy), archaeologist have found a mould for lead glans - the mould has been dated to Vth Century, and is the oldest evidence, that I know, of lead glans.
About the Italian Celts: it's possible that they used lead bullets, for that there were not deep differences in weaponry, between the Italic tribes. More, the adoption of Greece's way of life concerned even weaponry, and lead to some standards: big rounded bronze shields, long iron swords for cavalry, and some others. This can be seen in warrior's tombs and in bronze small figures of heroes and divinities (such as Marte, Greek's war God). But I don't know enough about Celts to say something for sure
Wirocu, I can bet that everyone used clay, pebble and lead bullets - the sling being one of the cheapest weapon ever invented

- and this makes slingers hard to be recognized when excaving a battle's terrain
You're right Thearos, Dionysios I founded Ancona in about 385 b.C.

But before him, there was a Picenian village dating about VIIIth Century and, more ancient, a Bronze Age village. In the centre of Ancona, on the main hill, a lot of flint tools and blades have been found, dating at the Neolithic Age. There's a long valley that links Ancona with Monte Conero, 15 kilometers South: I want to make some archaeological reconnaissance in that valley, to see if I can found some flint or stone tools - that could mean that the Neolithic people living near the Conero, have moved to my town. (I live exactly in that way, and I've found a Neolithic flint blade 700 meters from my house!).
What do you like about Fossombrone, Senigallia and Fano? Tell me, perhaps I can tell you more about them!

Where do you live? How do you have read Archeologia nelle Marche?
Greetings,
Mauro.