gnoahhh,
I will definitely look at the mold you talked about as that sounds like it would work. I definitely don't have anything against Lyman or Lee dies as I haven't cast much beside 45 and 9mm and those are all out of Lyman dies I believe.
I may have to look for a small frame Martini to do this on. Hornet would definitely work, I believe I have a bunch of K Hornet brass and dies.
Your project sounds fun, would love to see it. I just finished helping my uncle finish a 15 yr old project he had. An early Springfield 03 on a military stock with a barrel in 22-250. I head spaced it, finished the exterior and rust blued it for him. He built a barrel band etc to match his Springfield 22 trainers. I will look for a picture and throw on here.
