Hi Taz,

I don't really have experience of calibres that small but I would suggest that you may have to experiment to find the best ball and patch combination.

I do have a .54 cal patched ball rifle and that uses a .53 nominal ball and a 0.010" patch quite happily. On that basis, you might like to try a ball around 0.41" and then get a small quantity of different thickness patches and see how easy each combination is to load.

There may be some rook and rabbit gun shooters on the forum who haven't seen your post yet.

Steve.