I think you explained it well.
I called my gun an Edge, because most people over here are familar with that chambering, not because it's one of Shawn's creations.
I thought I explained the history and background on this gun and chambering pretty well.
I said the barrel is stamped 300/338 Ultra Mag. You can see that in the picture. I said I thought it was backwards, as in maybe 338/300 Ultra Mag instead. Also, my Redding die box says 30/338 Ultra Mag.
Brass WAS hard to find eight years ago, not now.
You need to use 300 Rem. Ultra Mag Brass only, necked to 338, with NO OTHER CHANGES.
Maybe I'll just keep the damn thing.