Have about 50 .348 cases formed and trimmed to .44-77, but the rims are .076-.077 and fit the Shiloh chambers, but not the C. Sharps chambers, which take a thinner .067 rim -- like the .45-70. This must have been the reamer my gunsmith used. So I need to find a "cartridge machinist" who can uniformly shave .01 off the forward edges of the rims on these cases. Anyone out there wants to raise their hand or direct me to a good source for this work? There will be cookies ... and biscuits for the dogs, if ye have 'em.

Jerry, it would involve at least $80 worth of shipping back and forth from Texas to Idaho, where John Taylor did the chamber and barrel -- probably using the reamer that C. Sharps uses -- and then more for John's time. The receiver and barrel have been beautifully polished, cased and blued by Allen Springer at Snowy Mountain. 
An alternative, suggested when I was searching for brass, was to simply form it from slightly undersized .45-90 brass.

Have you seated a primer and checked to see if by chance it seats below flush? I had a bunch of donor brass for my original Rolling Block in .44-77 that was too thick at the rim, but primers sat well below flush when seated. So I just turned off enough on the headstamps until the block closed and they worked. It was a lot easier, and simpler than turning the leading edge of the rim, and didn't require a mandrel to hold the case. Just flush the cases into the chuck, and run the cutter in. Then just repeat quickly until all were done. Anyone near you with a hobby lathe could turn the rims in a few minutes if the primer depth allows it.

Gert, that is an interesting option. I had not even heard of a rim swage die. Hope all is well with you!
Vall, a primer seats perfectly flush as near as I can tell. 
One of the chaps over at Castboolits has offered to do the lathe work for me, so for now, my problem is solved.
Gnoahh, the reamer is in Idaho and I am in Texas ...

You might want do a chamber cast,
The early CSA chambers for the 44 bn cartridges were designed to use 45xx cases

I use the lee 43 mauser dies for a lot of my 44-77 reloading 
The 43 Spanish sizes the neck down to far for everything except for drasticallyunder sized patched bullets

Just lay some 220 grid sand paper on a smooth surface and figure 8 the case head down to what you need to close the breach block.
I did this with my .44-90 bn using .082" rim thickness the Bell .44 basic brass had before Jamison started making brass or HDS had some.
Then just ream the primer pockets deeper or use pistol primers. 
Or find a friend that has a lathe with a collet chuck, that works best and chuck the case with the rim against the collet and just the traverse cuts. 
I just used that a lot for a large number of cases.
Also I used a mill with two V blocks sitting on the parallel bars and run the end mill over the case head. I liked doing it this way better than using the lathe. It's just a matter loosing the vise lift the case out or just dropping it in and tighten the vise.         

It seems ridiculous to have three different rim thicknesses. When I sent my .44-77 rolling block to C. Sharps for rebarreling, I specified it to be chambered for Jamison brass that has a ..073" - .074" rim thickness. He had no problem doing that. This is the rim recess of the original Remington barrel. The recess measures about .090"!