Can't you just skip to the 20 or 30 mm? Or just like the gradual approach?
I'm running out of steps to take!
I do like the jump in caliber between projects. The current one should be done soon (CZ 527 conversion to 6.5 Grendel), and then I'll get this one going. Here's the Grendel next to a parent case for the new 338 projecct.

Since the 375 Chey-Tac case wasn't big enough already, I'm going to go with an improved version.

If you're going to go overbore, go all out! This is what happens when I find a good deal on odd caliber brass.

Andrew