The .256 Win was one of two barrels I bought with my first Contender 35 years ago. I used it, with a 2.5 Bushnell, to hunt prairie dogs around Lubbock where I was a graduate student. After moving to Missouri, I used it to hunt ground hogs. I've also acquired a Texas Contender carbine chambered to it - fun - and have a Merrill Sportsman in that caliber (others, too, of course). It works fine on both prairie dogs and groundhogs, although something flatter shooting is nicer for prairie dogs. Oh yeah, almost forgot - it gave the most spectacular results on armadillos of anything I ever used on them. The .256 is certainly overshadowed by many more chamberings available today, but it is a fun little cartridge and is useful as I've indicated. The down side is ammunition and brass availability. It's not too hard to form from .357 Mag, but I get better brass life using .221 fireball and changing the extractor to a rimless one. It's a bit more work because of the initial trimming, but case loss is nil (not my experience with .357) and brass life is better. This strategy won't work in the Merrill, so I found a supply of .22 Jet to neck up and form. They seem to give better life than even the original Winchester brass, but maybe I'm getting more conservative with my loads in my old age :lol: I say go for it. If you decide to do that and need some brass I could probably be persuaded to part with some of my new Winchester brass - not a great deal of it mind you, but some.
Good shooting!
RonF