This is believed to be one of the calibre reduction experiments carried out by Swiss Professor Friedrich Wilhelm Hebler (1844-1932) who was a mechanical engineer from Bern, Switzerland but spent most of his time in Austria. In collaboration with Karel Krnka, he developed the copper-jacketed bullet along with advancements in bullet aerodynamics. From 1874 – 1891, Hebler carried out countless experiments in cartridge design. He was particularly interested in what he called “the smallest calibre” and published a series of books on this subject from at least 1886 to at least 1894. See also Hoyem Vol. 2 p.210 and IAA Newsletter 614 (June 2016).