mbogo,
Even though I use a 338 more often than not, my heart lies in the older late ninteenth and early 20th century chamberings.

I'm currently working with Ralf Martini of Martini-Hagn for a singleshot based on their Hagn action. I've owned a half dozen or so Ruger No.1's, but have always wanted a Hagn. After talking with Ralf in person at the ACGG show and actually handling a few of their rifles, I now know that I must have one.

My initial idea was this would be my mountain rifle, for sheep mostly. I had thought that the 275 H&H Mag would be an ideal fit in one of their medium size actions. A little further study into the cartridges of that era uncovers the original "hot" 7mm, the 280 Ross. While that is under consideration, the 275 H&H does carry a little more "panache" since I have a pre-64 in 300 H&H. I think it would make a nice pairing. This Halger interests me, since Taylor's work is the only time I've seen it in print. I tried referencing this in Cartridges of the World, but it's not listed.

Oh, then there are the wildcats, I had thought of just necking the 300 H&H down to 7mm (not the 7mm STW), or necking down the 333 Jeff. Of course, one could also do something similar with the 318 WR.

I guess I am looking for a case or cartridge that was introduced sometime before 1920. Ballistics are really a secondary concern. I think the 280 Ross, 275 H&H, probably the 280 Jeff, and 280 Halger would all meet or exceed the 7mm Rem Mag. I suppose if the 350 Rigby were necked to 7mm, it would give similar or slightly better velocities than the Rem Mag version while keeping pressures down. I've seen references to the 275 Rigby Magnum, was this the same animal?

Thanks for all your help. You gotta really appreciate these old cartridges.