Definitely the RMC has been my best brass for the 50-140, very consistent and about the right metallurgy for repeated reloading. You'll love the caliber both smokeless and true black. It's amazingly accurate especially once you get into the paper patching world. With paper patch I have chosen a bullet and paper thickness combination to give me a diameter that when wrapped, I don't have to re size the brass after firing-- you understand why when you price out the brass -- otherwise you can anneal every so often if you re size a lot. The friction fit is enough to hold the loaded wrapped bullet, and there is a small amount of spring back after firing - the reloaded round chambers just fine. Accurate powder has quite a few listings for loads - pressure is about 28,000 for loadings -- email them for heavier bullet loadings. Good luck and keep us posted. Shiloh's web site has lots of info for patching - but it's mostly geared to patching to bore diameter instead of groove diameter for the wrapped bullet.
Surprising to me you guys don't try the paper patching in the 45-120 or even the 45-70. It's another whole new adventure.
Bob.