I have a Parker which was re-colored twice within the first ten years of its life, which began in 1897. I know this because the factory records state so. That should give you an idea of how much the gun was used. In the ensuing 100 years it may have been recolored after that as well, though there is no record of it and the gun has little color left on it now.
The frame must have been faulty as it has no signs of cracking.
Regarding the Fox, I wonder how a ugn which was recently refinished by a well know refinisher could have a doubling problem. I would expect that if the gun had been properly put back together any cause of doubling would have been remedied. Is this a case of putting a new paint job on car with a gerasy engine?