GF,
Here's the current progress report.
Soaking the assembly in Liquid Wrench, PB Blaster and ATF-Acetone didn't seem to do all that much, at least with the equipment I was using.
I finally made octagonal aluminum jaws to keep the barrel from twisting in the barrel vise. Even with lead packing in the round ones, the assembly would turn instead of loosening the action. The internal Shaper practice I got from the exercise is always worthwhile.
The barrel clamped tight in the barrel vise, and the assembly soaked for months in the various miracle juices, it still took three full-power bashes from my 5-lb maul on the action wrench handle to get the receiver loose, and I had to leave the wrench on to turn it the first several turns to loosen. Oddly, there was no rust on the threads, just light patina and whatever liquid had managed to penetrate. All it takes is to be screwed on tight and left for 100 years to get a near weld.
I then soaked the parts in Evapo-Rust. I have to say, having checked out any number of child-safe, environmentally-innocuous, nontoxic products, this is the one shining example that actually performs the office it's advertised to perform, rather than just sitting there and signaling its virtue. Except for the deeper pits in the barrel, all the rust is either washed off or turned to a gray-black sludge that can be wiped off the surfaces, leaving them clean, gray metal.
I started drawfiling the barrel and was gratified to find that there weren't a lot of really bad pits, and those there were small and mostly on the bottom.
I got a .50 caliber liner from TJs and ground a pilot on a drill to fit. The drilling ordeal will soon commence. I had a couple moulds and a couple clutches of .50-70 shells and don't have a .50 rifle, enough reason for me.
I got set-trigger parts from MVA, and a coil spring from somewhere (can't remember), and with your kind donation of a knockoff, put the action together. It doesn't always cock, and when it does, it doesn't snap, but the parts are a melange of new, old, and rejects from the bin that CSA used to have out at Gun Shows. Had to weld a lump on the front of the lever and dress it with my index table on the mill. It will have a spring off the barrel just to hold the lever closed, and the coil spring for powering.
Here's the drill, liner, barrel and action so far. The Evapo-Rust gray finish on the action is not displeasing. Maybe some company will offer it as an option some day.