I have a sporter done on a 1903 Greek action to 256 Gibbs Magnum cartridge.
From what I've found (and I believe everything I read on the internet), the cartridge is based on the 6.5 Swede.
Another proprietary cartridge, and probably not unlike some of the other more modern short 6.5's mentioned above.
Gibbs probably had a machine set up just to do the magazine rotor cuts for the conversion.
Not that it can't be done and hasn't been done, but the number of failed and now project '03M/S caliber conversion guns I've seen far outnumbers the successful conversions.
The successes are usually taken at the word of the seller/owner. Not much of a chance to try before you buy at a shop or show.
The 05,08 & '10 M/S conversions seem to work out much better as the magazine spool cuts are so much closer to the conversion caliber size .
There's really nothing wrong with the original chambering. It's an old one and that seems to bother more than few people. It doesn't hint at a magnum status either,,another black mark in some circles.
A set of 6.5x54 dies is easy to get. Buy a couple hundred new cases, scrounge some older stuff trolling the shows forever, or even make them from 220Swift like I do.
6.5 Mannlicher Rimmed is a nice round too for an early Mannlicher or a singleshot.
I haven't really searched to find what I need to cobble cases and rounds together for the 256Gibbs Magnum yet. It won't be as easy as the original caliber though.
RCBS probably has special order stuff for just under $200 or something like that. I'm thinking a less expensive route!
Meanwhile, it's kind of nice to look at.
