Well…after a lot of reading and thinking, I decided it was time to have a go. I've got plenty more brass in stock.
I basically ran the chuck as slow as possible, and moved the knurling tool along by hand whilst trying to keep an even pressure on it by constantly adjusting the tool post.
Not an easy task.
Anyway, here's the end result. It's not great, in fact it's far from great, but it is at least nice and 'grippy' in the hand.
I think I'll keep it until my Birchwood Casey brass black turns up, and see how it looks once it's blackened. If I'm not happy, I'll probably take it off and make a ribbed version, or perhaps try separate knurls interrupted by grooves. Until I get everything loctited up and peen the tang thread, I can experiment a bit, which is all part of the fun.
Funnily enough, I did toy with the spring idea, my thoughts being making some sort of spring loaded tool holder with an old airgun spring.
Certainly an interesting project. Thanks again for sharing your thoughts.
Cheers,
Ian.