Some hang together longer than others, but they all seem to separate sooner or later. Not in a manner usually thought of in that the rib(s) fall free from the tubes but they do develope loose/gaps along the seams and eventually there's more loose area than soldered area.
Another problem is that the hot blueing salts gets inbetween the ribs just like the hot water does in rust blueing.
Hot water is easy to steam/evaporate out but the salt soln. is difficult to rinse out through a tiny weep hole.
The salts can corrode in there and grow a white 'bloom' as they absorb H2O from the air.
Oil won't kill their activity.
IIRC one of the last batches of Ithaca NID BBls were hot blued by the factory and found to be unsuitable. The bbls were scrapped leaving a number of finished small bore NID stocked actions w/ forends around for many years.
One 'trick' used by some gunsmiths was to use a small amt. of potassium cyanide in the hot salt blueing tank while doing soft soldered bbl sets. Supposedly it protected the soft solder/lead component from the attack of the blueing salt compound during the process. Wether it worked or just delayed it, I don't know.
I just view hot salt blued bbl sets (soft soldered) as haveing to be redone at some point.
I've seen Spanish and Belgian guns with silver soldered tubes. There are undoubtedly others, but never a Parker, Fox, LCS, Ithaca, etc with anything other than soft soldered ribs.
