Here is what I did. I used a chamber reamer to make five dies that head spaced (more or less) on a case in a shell holder. The raw material for the dies was a piece of 7/8-14 threaded rod (3' for ~$28), this saved a bunch of time since I didn't have to thread the stock. I then drilled the chambered dies out in roughly .020" steps. This gave me a set of forming dies that basically keeps the should where it should be and cost near nothing to make (except time, but I don't charge myself much).
I then performed the following steps:
- Cut 223 case at the shoulder
- Trim all case to same length, squaring the mouth and then deburr
- Run case into each of the five forming dies
- Runt he case into a small base 223 to shrink the body (probably not needed)
- Run the case into the 17 FireBall
- Inside neck ream (I made a guide that fits into the depcaper that holder a .168 chucking reamer
As long as the I start with a good square case mouth I have zero loss. I haven't fired these, but I have popped a few primers, I confident the shoulder will blow out. What do you think?