I'd guess that the stamp "POLDI ANTICORRO No. 280" is a steel type recipe, which was evolving at the time. It appears that Karl Wittgenstein's Poldi Hütte Kladno facilty(Krasna Poldi - Beautiful Poldi poem) in 1910 was the 1st to turn out stainless steel( Rostfreie Stähle ) and there were a couple of variants like AK(AnitKorro Stahl), AK1, AK2, AK3, etc. Poldi Anticorro contained 10% nickel was acid and corrision resistant to the point that it took 5 to 10 times the application of rust bluing for the finished product.
Baumgarten's Selbstspanner Sicherheits Drilling Patent Brennke took a great deal of effort which may have been a year or so in the making and it may have begun as early as 1910, the 1st year Poldi's Anticorro was produced. So the drilling had the latest and greatest steel type recipe at the time. There was nothing short about this drilling and the price reflected it.
Circa 1900 the Poldi Hammer hardness tested was developed and the following site has an interesting description:
http://www.alexdenouden.nl/08/poldi.htm
Kind Regards,
Raimey
rse
