By 1943, the Hungarians had run out of 8x50 R ammo with the “original” RN FMJ Bullet, so they just used the 8x56R case draws, trimmed and sized to 8x50R specs, and loaded the 31M Spitzer projectile into it.
Both AH and ML factories made this round. I have both ML 43 and 44 dated steel cases with this projectile-- came out of a small batch of Mixed 8x50R ammo along with a sporterised Budapest 8x50M95 Stutzen back in the early 70s (probably from an American visitor on a boat). The ammo included AH pre-War 8x50R, some Italian “8 M 1937” (Hirtenberg contract) and some AH “Training ammo” ( two piece bullet), as well as the LM Syteel cases.
The Mixture makes me think it came from US importer in the mid 50s to 60s, when such ammo was widely available in the USA with Cheap Milsurp rifles, also in 8x50R.
Only the Hungarians made steel cased 8x50R with a 31M “S” type bullet as a wartime emergency measure…I have never seen any Austrian or Bulgarian 8x50R ammo (brass or steel) with 41 to 44 dates…
Interesting cartridge , interesting times.
Regards, Doc AV