The original strings used by Mills were steel and needed considerable
weight to tune them.  If working on a machine with the original unaltered
weight buckets, only steel will tune properly.

On the Violanos I have worked on, including my own, I have used wound
strings with gut core, but the lead in the weight buckets for the D and
the G strings must be melted out with a torch, and very small lead
pellets (shot) used to re-weight the buckets at the lighter weights
required.  I believe most restorers today use the gut core strings.

Dick Hack