I won this over a month back and just now got it. Brazilian Steyr 1912 model. Bolt doesn't match and yes that black paint was likely over all exposed metal except the butt plate. Sadly that is too bad as the exposed parts as the stuff appears to have worked pretty well. The markings appeat...
That's my thread for it. Steyr made mauser sent to Brazil.
The link below is still active and contains a Gunboard list that ct241 started to try to catalog the various Romanian Vz24s that are still around. Your rifle pictured with serial FR21380 is not on that list so I'd pull up the link below and add your info to the list. According to the link below, your rifle probably was a Second Contract rifle with a King Carol crest before it was scrubbed and it was likely shipped to Romania on February 16, 1940.