7.5m/m Schmidt-Rubin nomenclature

I have a Schmidt-Rubin cartridge for which the proper ID has so far escaped me. It has a paper-patched plain lead bullet (no steel cap) and is in a M90-type case with a flat brass primer. The headstamp is B T 12 11 (B at 9 o’clock, 12 at 12). I’ve had this round for a very long time & have never been sure what I had. Can anyone help? JG

JG, I may have the same round. and I would also like to have an answer. Does the primer have black seal, and is the neck paper patched down to the shoulder on yours?
Thanks,
sam

Hi
Do you have this round ??
this is a 7,5 GP 90/03 Mod.1889

headstamp D 11 T 3

reagards
gyrojet

gyrojet, I have it with T 10 T 06 headstamp, and have both rounds as 7.5x53 Model 1890. I would like to know what they should be called, as the full patched lead bullet, looks a lot different.
Thanks,
sam

I hope I’m not adding to the confusion but I have two rounds in this calibre with the 53mm caselength and have come up with the designations of;

7.5mm GP90 - (T 6 T 06) paper-patched roundnose lead bullet - pretty much as described by J.G.

7.5mm GP90/03 - (T 12 T 00) paper-patched, steel-capped lead bullet - as pictured.

I cannot remember where I found these designations but it was very likely from Gordon Conway’s Collector Cartridges catalogues. These are generally extremely reliable for those that haven’t seen them.

Jim

Jim has the right designations for the lead bullet, and the metal-capped bullet. The basic 7.5 ball rounds were:

Model 90 - Round-nose, hollow-base, paper-patched lead bullet wieighing 211 grains. MV approximately 1,970 fps from a compressed charge of semi-smokeless blackpowder called P.C.88 developed by someone named “Schenker,” a chemist who became the manager of the Federal Ammunition Works (Eidgen

Certainly of great help and interest to me!! Thank you John.

bullet’s for the 7,5

Thanks to all for comments. I’m sorry I had to be away from this thread for a couple of days. My cartridge does agree with the one mentioned by Sam, having a very long paper patch coming almost to the bullet tip. I have the Grieder article & for a very long time it was my sole source on Swiss rifle ammunition. There are some aspects of his ID that concern me however–one is that he mentions a rounded primer cup (which is correct for very early S-R rounds) whereas mine has the flat brass cup and why the M90 would have been produced as late as 1911, long after being superseded by the M90/03. Finally my cartridge is does not have a compressed propellant charge, as it can be heard easily when shaken. Again, thanks to all for information and interest. JG