The 8x50R (A-H Mannlicher), subsequently used also by Bulgaria, went through several variations, from the 1888 Cartridge, with semi-smokeless Powder, to the M90 Cartridge, but 53mm Long, 5o the M93 (sic) with the case length set at 50mm length.( and used in the M95 series of rifles.
The M93 cartridge design lasted in service till the mid 1930s, but was still being made up to about 1945 in Austria, Hungary and Bulgaria.
Now, the Bulgarian side of things…Bulgaria started making “8x50R” back at the Beginning of 1900s, after adopting first the M88/90 rifle, then the M95 from Steyr. CA (or “AC”) entwined stands for “Sofia Arsenal” where initial manufacture began. SFM (France) also supplied large quantities in the 1904-06 period.
With the adoption of the 8x56R (Austrian M30. Hungarian 31M) Cartridge in 1934 by Bulgaria, they started making 8x56R ammo in quantity in 1936; 8x50R production was slowed to termination, and Bulgaria in 1935 bought a large quantity of 8x50R from “Circle M” (Bratislava, then Banska Bystrica (Slovakia).
Next, using the Austrian Rifling system, the Bore is 8mm (.315") the Bullet is .324" (ie, NOT “S”, which means Spitz, or Pointed, in German), and the Grooves were .329-.330.
The Cylindrical round nose Bullet was designed with a flat, slightly concave Base, to “Upset” into the deep rifling, and create a “gas seal drive band” ( Term, “Base Upset Obturation”) common to all the early, (1880s-90s) Cylindrical Round Nose calibres, ( from 6,5 to 8mm), to create less frictional drag and heat from a perfect Groove diameter Bullet.
Only with the onset of the Boat-tailed Spire Point, and even flat based spire Point, did the Bullet Diameter equal the groove diameter, as Boat tails don’t “Upset”…Hence, the German “S” and “sS” are .323" diameter, as are the Austrian M30 “S” at .329" diameter, for the Groove diameter. Again, “sS” and “S” denote “pointed” and do not refer to Diameter at All. Even the Argentinians had a 7,65mm Projectile as “S” ( 154 grains), and SS ( 175 grains BT.): sS schweres Spizgeschoss ( Heavy Pointed Bullet).
Prime Users of the Mannlicher series of Rifles were (1) Austro-Hungarian Empire ( to 1918); (2) Republic of Austria 1918-1945); (3) “Kingdom” of Hungary (Regency) 1918-1945; (4) Bulgaria (1897? 1945);
Secondary Users: (5)Czechoslovakia (1918-1930s); (6)Poland (1918-1930s); (7) Russia/Soviet Union 1915-1930s (8) Italy Colonies 1919-1943); (9) Yugoslavia 1920s-1940s; (10) Greece (1920s-30s); (11) China Warlord Period (20s and 30s);(12) India (1941-45)
(13)British African Colonial Police (Various ) 1941—1950s;(14) Also supplied by Soviets to Spanish Republicans Late 1930s (SCW).
This List Includes Original 8x50R chambering, the 1930 8x56R chambering, and in the Case of Yugoslavia and Greece, the 7,9x57 (Mauser) Chambering. (15) Almost forgot, Kingdom of Siam, late 1890s-1902)
Manufacturers of 8x50R ammo ( from 1880s to 1950s)
Austria/Hungary, France, Germany, Poland, Czechoslovakia, Italy, Bulgaria, India and China, for sure; But Russia/Soviet Union ?
Only India still makes it, as the .315 Indian sporting cartridge ( For 8x50R-chambered SMLE rifles for Shikari (Professional Hunter) Use --Both BSA Pre-and Post-WW I export rifles, and I.B.of Ord.-Made SMLE sporters for internal commercial sales.
Note on the Czech and Bulgarian “fresh” (1935) made ammo; Brass Case: Roth-Patent Berdan Primer ( 0.199"/5,0mm) diameter, with Corrosive priming compound. Anvil has central flash hole through it; can be decapped Hydraulically or with a 0,8mm diameter Pin (on a shank of 5/16s"). Berdan Primers ( RWS #5004 and #5005) are no longer available in USA. Pocket can be milled out to Boxer .210" (LR) with a #4 Drill flattened to slot drill format (End Mill) Flash Hole can be opened up with 1/16" drill or 5/64". Cases will need neck and shoulder annealing before reloading.
Powder: European (Germanic style) Diamond Flake Rifle Powder, about 45 grains or so. Bullet: Cylindrical RN, FB, Steel Jacket Lead core ( Jacket lightly Nickeled.) 244-247 grains; Diameter .324" average.
Packet clip: M95 Packet clip ( with windows) and Factory Logo or Letters on Back ( see Gunboards archives for all the close to 50-odd Factory codes known.). It is an Asymmetrical clip (i.e., goes in Only one way); Earlier M86 (11mm ) is larger, and has no windows, neither does the M88 (8mm) clip, (no windows);
Brass clips are unknown (to me); Clips are almost all Blued spring steel, some may be Tin Plated (???).
8x50R ammo in the US is mostly the Czech Circle-M cartridges (in “Z” marked Packets of Ten rounds); ZB Brno bought the Bratislava Factory in 1934-35, and shifted it to Banska Bystrica, where it became (during WW II) part of the “dot” code location). There is some 1930s Bulgarian as well. In the 1960s, there was a lot of (Interarms) 8x50R, from Austria, Hungary (“AH” Logo, ) and Italian Made ( also Hirtenberg for Italy).
That should give you a good grounding for future research on the Web (Google, Gun Board, Parallax Curio & Relic, IAA ( cartridges) etc.)
All GB members will help where and when they can.
( Old Grizzly Bear, Curmudgeon, and Master of the Antidiluvian Order of Berdanners (SWPacific Region )