Made a mistake above.
Here is Dixon's text for the 9,3x60, as cited in the IAA forum:
“Apparently introduced c1905 by Roth (case #724) for a PETERLONGO Repeating Rifle. It is shown in a 1909 Peterlongo catalog and c1910 Roth catalog but not listed in a c1912 Peterlongo catalog. This cartridge has been rumoured to be a Krnka design but this is now considered unlikely. This was also produced by the Czech J.Roth company (1918-1928) and both “GR////" and "JR//724/*/” hs (c1923-1928) specimens exist. “Zbrojovka Brno, AS, zavod II Povazska Bystrica” (the eventual successor to JR) stopped the manufacture of this cartridge c1937/38. Shown in a “Ceskoslovenke Munici a kovodelne zavody Bratislava, AS” (M) catalog as a 9,4 x 60”.
So there were cartridges known, both with GR and later Czech JR headstamps.
