Actually there is a point here. I do a lot of stip and relays, it is surprising when you get the ribs off what the barrels are like in between . Most will have some rusting and pitting . It is not certain what was the original cause of this. It is also a fact that some comparatively modern guns have serious rust and pits. It is also a fact that some 100 plus year old guns have virtually no rust or pits at all. It has in my opinion to do with how well the ribs and barrels were tinned up before the ribs were soldered down and how long the ribs have been either loose or have had water get inside them ,as much as it has to do with the fluxes used in the actual soldering.
This runs true with guns of all makes and from different countries.
I think the point must be stressed that no gun maker built guns that were meant to last forever and the fact we are shooting guns that are 100 years old is testament to the skill and ability of those men.
But whether it is fair to say all old guns have rust pits under the ribs and are unsafe is a sweeping statement and is akin to saying all drivers are dangerous .