How does one go about creating .32-40 brass?  I've read where they can be made from .38-55, .30-30s, .32 special.  Which would be the best?  I know, as soon as I make a few hundred, some manufacturer, somewhere, will start producing them again.  I do remember, not too long ago, W-W .32-40 brass cases on the shelves in some smaller shops.  Day late and a dollar short again......

Hornady 32 special brass works, just lube it up and run thru the size die load and fire form.
You have to watch 38-55 brass, as the brass can get quite a bit to thick at the mouth after you size it down so sometimes inside mouth turning is necessary.
Keep a close eye out as Winchester does let out a batch of the 32-40 's every once in awhile, but you don't want to hesitate when you see it, either buy it or crab about not having any..

All the 32-40 brass you need can be made from StarLine 38-55 cases. Both the 2.080 and 2.125 length cases are currently available from StarLine.
You need to anneal the brass approximately half way down the case body, use case lube sparingly but make sure the case is completely coated. Full length size brass in multiple stages, redistributing the lube on each case between stages. Go slow and be aware of what you are doing and you will only loose about 3 cases out of a 100.
After sizing, trim brass to precisely fit your chamber. Make a CerroSafe chamber cast so you get accurate measurement for case length.
Having a 100 prepared cases for a rifle makes match day a bit easier. I've been doing this for the past 4-5 seasons for both my offhand and bench rest 32-40s.
If you are one of those shooters who prefer to use only a single case, buy a handful of cases from Buffalo Arms, then anneal, resize and trim them for your 32-40 rifle. You will be good to go for years to come.

I'm toying with the idea of have a .32-40CPA built, or changing my Savage #12 6mmBR into a 30BR, for cast PBB.

CPA's are good rifles. Another one you might consider is an  1885 from C Sharps.

Well it may be this particular lot of 38-55 brass was a bit thick to begin with. The person I bought this Ballard from said he couldn't shoot black powder in the rifle it would pull the brass in two. Sure nuff, he was right. Upon further investigation, the reformed Starline he included in the sale, would not take a sized bullet back in the fired case, the neck thickness is to thick.. Even expanding it and loading with smokeless it is hard to chamber, but at least it won't pull in two.

What about resizing .32 Win Spl?  I've read where they are a bit short, but when the actual brass case has very little to do with the OAL (breech seated bullet).  Why not take a .32 Win case and full length resize it in a .32-40 FL die?  I like the sund of Starline stepping up to the plate.  ED

Snort, I've reshaped about all the suitable caliber cases into .32-40s, and using .32spl. is the easiest of the bunch. They are not too short to use for fixed at all. A little more of the bullet lube will be outside the case, but for use at the range, who cares?
I usually only end up about .040 shorter than my "real" .32-40 brass, and cannot really see a bit of difference fixed or breach seated, as far as the brass itself is concerned.
But, if you have a big pile of ol' .30-30 don't let it go to waste- it'll just be a bit different in length- still just fine.