That is a very good idea, I went out in search of some suitable brass today but all I could find is tiny 3/16" 0.18" diameter rod. I will look around my spare parts bins and see what I can find later that might be suitable.

I will see about dismounting the barrel and making some vise blocks out of wood, from there I will see what can be done.

One another note I did manage to find some Oak dowel in various size and length which I need for another project. Hardwood dowel can be a challenge to find these days, loads of useless poplar and other softwoods are the most common.