Tell me about the .256 Winchester Magnum.

Q: I recently obtained a Marlin Model 62 lever-action rifle chambered in .256 Winchester Magnum in as-new condition. The guy I bought it from threw in 60 once-fired cases and assured me that loaded ammunition is available as well as loading data. What can you tell me about this rifle? Where can I get new ammo? My local gunshop has never heard of this rifle and cartridge.
Don Burgess

A: The Marlin Model 62 has a Micro-Groove barrel with .257 groove diameter and 1:14 twist , which will allow the handloader to use 87gn bullets. The .256 was designed for handguns, but it was Marlin who brought out a rifle for it back in 1962. Winchester loaded ammo with a 60gn open point expanding bullet at 2760fps generating 1060 ft/lb of muzzle energy. This makes it considerably more powerful than the old .25-20. It can be loaded with heavier 75gn and 87gn bullets to velocities of 2500 and 2300fps respectively. You may think that you’ve bought a pig in a poke as Winchester was the only commercial manufacturer to offer .256 Win. Mag. ammo, and they discontinued it in the 1990s. They do not list unprimed brass any more. However, you can make .256 cases by buying .357 Magnum brass and then running it into a .256 full length die. You may or may not have to anneal the.357 cases first. The only reloading manual that currently lists data for the .256 Win. Mag. is, I believe, my Practical Reloading Manual.