rechamber 310 martini - 32win?

[Rapier]

The little Martini action is a 60-65K action, so it is suitable for any modern cartridge that will "make the turn," is rimmed and has a base diameter of .422 or less. Interesting thing is that it is a BP action that in the US is not considered a firearm, regardless of what it is chambered in. Once a BP gun, always a BP gun. 99% of the buyers and sellers are not aware of the BP status of the Cadet, which makes the little guns very unique.

The 357 SM is a good cartridge, used with rifle bullets. The 180 is capable of 2100 fps. The 30 Harrett is capable of 30-30 performance in the single shot action. The JDJ cartridges have a body length that is a problem based on my conversations with JD Jones.

There is a series of cartridges that would be interesting, the cartridges designed for single shots, based on the 357 SM. Of the series the 270 Max and the 30 Max are best known. Both are very accurate and offer good performance. However, dies and a reamer will be dear.

I suggest you decide what caliber, what bullet weight and what velocity you are looking to attain Then look at the stats. If you need help, I have cartridge design software.
Ed