Many years ago, I inherited several boxes of 45-70 brass. I'm not totally unfamiliar with the cartridge but had no need to reload it..until recently.
My son just bought a Marlin Guide Gun and I sent him three boxes of new Winchester brass. While sorting through the boxes I realized I had several with government markings, used as blanks for a line throwing gun. These cases are all the semi-balloon head type, a slight improvement over the old standard balloon head. They appear to be in excellent shape, almost new. Would I be correct in that they'd be adequate for low/moderate pressure loads, say in the 1873 trapdoor pressure range, using smokeless? They show no signs of having been used with black powder, i.e. no residue, corrosion, etc. Nice, clean looking old brass.
These cases would be for my own use, not given to anyone who might load them like a solid head case.