Only way to know for sure, of course, would be dye penetrant testing (which, if you could find a lab, might cost more than the frame) - -it's like magnafluxing for non-ferrous metals.
Short of that, you may have to scrape away enough paint and clean down to bare metal for a better visual inspection.
The bear - - Friend of mine (actually my old mentor) - - an old-school illustrator and cartoonist - - did that caricature of me and the bear.
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Originally Posted by Mark Twain
"Don't argue with stupid people; they will drag you down to their level and then beat you with experience."