Years ago I read an interesting info about this Volunteers unit that fought even if piecemeal not only at Castelidardo but also at Spoleto ecc..even if provided with surplus uniforms, inadequate meals (once they strongly protested and almost rose up cause they could nt stand the spicy Italian food and the lack of beer provisions) and lacking basic military tools , according to the Italian Official History published around 1930 from reliable sources the bersaglieri and Italian infantry sieging the fortified garrison of Spoleto were amazed to be outranged and outgunned by those very good Irish volunteers that pinpointed them with accurate shots from their rifled carbines..a weapon probably unknown in the Papal Army of that period and, as concern the Piedmontese one, probably distributed only to a few selected companies of the bersaglieri ..my only explanation could be that, maybe , the Irish volunteers carried their own weapons bought trough some sort of fundraising among catholic communities …
I very much doubt they brought their own weapons, the volunteers had to travel as private individuals, many with cover stories and bringing weapons with them would make holding up that story very difficult. I haven't seen it in the personal accounts ive read in fact most describe travelling as a tourist and becoming a soldier on arrival.
On arrival the Irish were issued with outdated Smoothbore weapons, and very little in the way of uniform, it caused a a lot of consternation amongst the men. There are stories of volunteers buying their own weapons and I'm sure one or two of the lads had borrowed weapons from other people :

Regards Ken
The Yarkshire Gamer