110 grain Jacketed ball
1900 Feet per second
Remember the .256 Hawkeye versions of the Ruger Blackhawk, and, I believe in the Ruger singleshot #1 rifle or carbine for a year or two?
A pal of mine reworked a Martini Cadet singleshot to take the .256 cartridge but with the case neck expanded to use a .308 bullet, which offered a much wider selection of bullet weights and styles. That was a good bit more esoteric than the usual reworking of the Cadet actions to a .38 or .357 revolver cartridge, common at that time, but the resulting rifle was a little joy both to carry and shoot, and took a good many whitetails in the Kentucky woods for its owner. I suspect a .38/.357 would have done about as well, and even an M1 carbine will do okay with a good hollowpoint bullet for such work. But that was a sweet little setup.
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I bought it not too long after the Ruger pistols were introduced.
It was far more accurate than I would have thought and of course would fire about half a dozen different cartridges. I don't know exactly what the ballistics were from that longer barrel but they must have been pretty decent.
For a couple of years just about every time I would traipse through the woods I would carry the rifle and stick a Beretta model 70 .22lr in my pocket.