Question about 5.7 Spitfire

[Postell]

Has anyone ever used a cutdown 223 sizing die to finish forming and resizing cases?

[scb]

Not this specific combination 5.7/223 but I tried it with something else. It was a long time ago and a dismal failure so I don't remember what it was. I do remember it was impossible for me to maintain concentricity between the neck and the body of the case. While It's not impossible to get a useable casing doing it the way you propose, I believe you'll be throwing away a lot more brass than you'll be shooting. I shoot the 5.7 and I know forming and loading dies are expensive. Maybe someone else will have a better solution.

[Postell]

Thank you..