256 WM was my first Contender caliber back around '89 and I still have it, although it is a 10" octagon barrel not a carbine. Bullet selection is somewhat limited. The only 60 gr jacketed bullet is the Hornady 2510 flat point at around 2300 fps from my pistol. They'll do quite a bit better from a 24" I imagine. My barrel also shoots 75 grain spire points very well, albeit slower. The heavier bullets carry their energy out a bit further than the 60 because of better BC and more momentum, but they don't shoot quite as flat. I never did get around to trying any cast bullets. My barrel would not stabilize Nosler 87 grain boat tail ballistic tips and I'm almost certain that to do what mcwoodduck alludes to (imulate the whisper) would take a custom barrel with a fast twist as the whisper also requires.
I really enjoyed shooting the 256, although all I did was punch paper. However, my 223 barrel does everything the 256 did and bullet selection is greater so I seem to shoot it more. Muzzle blast is about equal between the two in a short tube (in other words, lots of blast). I had good accuracy with H-110 and not as good with H4227. It's a dandy little caliber though.
Curtis
P.S. Forgot to add......... Forming dies are very expensive, but if you are patient and use only brass 357 cases (no nickel) you can form them using only your sizing die by working it a little at a time. You'll get losses due to split necks though. I have about 200 rounds of factory 256 brass though so I didn't play with forming very many from 357.
