Today,me and an archeologist went to see some ceramic projectiles in a museum bout 75km from my place.
There was also a brick with a COH III HISP stamp on it,and there are two stones with inscriptions mentioning the prefect of the COH HISP. nearby. There was a fort near Enlaka,where this Cohort was stationed.
I'm a bit excited,because equites cohors means mixed troops of cavalry and foot. From 500-1000 strong,depending,we don't know exactly,for now . Usually about 2/3 infantry. And they found ceramic sling ammo,still need to be confirmed if around the fort.  That could mean Hispanic or even balearic slingers were stationed in that fort.
I'm just too excited,and searching for more info on this. With permission from the "boss" of the museum we took out the balls, measured their diameter,and their weight. 12 pieces. 10 were 100-130g (which what i make and use) and two would have been about 200g ,but they had pieces broken off,like many of the smaller ones. I've seen very similar pieces broken off of my ceramic balls after impacting hard surfaces. They all had sand mixed in,which is totally sane and normal,so they could fire them without bursting such thick and solid ceramic pieces. Felt good to hold them in hand,and of course they felt very familiar,just something i would make for battle. The smaller caliber for range pounding,and the big ones for closer helmet crushers. They are turned up with their intact side up.The smaller calibers are around 50mm diam.

Thats great! Now that you have seen the real thing, could you do a tutorial on how to reproduce them?

This is a great find! Thanks for sharing with us.

fantastic find.

But it doesn't necessarily mean there were mercenary slingers attached to the 'romans'. Might simply have been the legionnaires hunting ammo. Plus roman soldiers were trained in sling usage.

Is there any evidence that balearic slingers used clay ammo ?
I'd have thought that would have been something that would have passed down the generations - don't they pretty much all use stones these day ?

Not mercs, but infantry auxiliaries as part of the cohors equitata-- i.e. non legionary, non-citizen infantry. Could be for infantry use (and I posed earlier links showing the surprising prevalence of clay ammo in Roman forts), could of course be for use on horseback.

DUring the republic, some might be volunteer mercs, some might be conscripts from allies or delivered as part of military obligations.

During the empire, auxiliaries are professional soldiers, volunteers, and as you say, after 25 years, they get citizenship.

I just found some molded ceramic sling ammo from Malaga.
Lightweight,from 42-52g,for distance slinging,mass produced.
So perhaps Balearic slingers also used ceramic. Why not? If they were famous for accuracy,and molded ceramic ammo can give you way better consistency than even selected stones..

http://www.britishmuseum.org/research/collection_online/collection_object_detail...

They may have been manufactured in the same series of moulds, in one place or carried on campaigns...