While at the show I acquired a set of used 256 Win. Mag. dies. The 256 was orginally the caliber of the unsuccessful Ruger Hawkeye and Marlan chambered a rifle in the caliber in the 60's. However, the caliber is obsolete, brass is well nigh unobtainable, and boxes of ammunition sell for about $50/ea. Needless to say I didn't buy any ammo. Not to despair. The 256 is basically a 357 magnum necked down to 25 caliber. The first step was to sort through all my 357 brass and pick out all the non-nickled cases as I didn't want to subject my steel dies to the harder nickel surface when case forming. The brass cases were lubed and run part way up into my 30 mauser die (thereby creating a new 30/357 case). The 30/357 cases were then full length resized in the 256 full length resizing die. This results in a case that looks more or less like a 256 case except it was too long. This was remedied by grinding the cases by hand to slightly undersize. (My intent was to trim the cases to size with a regular case trimmer after firing them once in my chamber.) About 15% of the used 357 cases were lost due to neck splitting during the process. Repeating the procedure with new Remington 357 cases resulted in about 5% scrap. The necks on most of the scrap cases were split with a dremel cut-off tool to make dummy cases for testing overall cartridge length with different bullets.
As it happens .257" diameter bullets were left over from a reloading adventure with a 257 Roberts that never showed much promise of accuracy and ended up consigned to that great gunshow in the sky. In a case of this volume I tend to start with 4227 and AA1680 powder. The previous keg of AA1680 had been nearly used up so for this gun I started with H-116 which is, as nearly as I can guess, a non-cannister version of 1680. Loads were assembled with 75g Hornady JHP bullets using an extremely conservative starting load and tested at the Elm Fork public shooting range in Dallas. All loads functioned well, but alas the gun shot eight inches higher than the lowest setting on the Redfield aperture sight. A sketch and careful work with the calipers convinced me one of the Lyman 17A front globes would correct the position of the existing front sight. The Lyman was ordered from Spartan and my local gunsmith put it onto the gun. A second trip to the range confirmed that the gun shot to point of aim at approximately half of the vertical adjustment on the Redfield rear. Group sizes ranged from 1.25" to 1.75" inches for different loads and the the H-116 powder seemed to provide the best accuracy. Further investigation with 4227 was discontinued. During testing I ran out of Hornady 75g bullets was unable to locate any of these bullets locally. Sierra 75g bullets were substituted and no difference in accuracy was observed. At one point I also tried 87g bullets but these mostly went into groups of about six inches which discouraged further experimentation with heavy bullets.
By working up in 0.2" grain increments of H-116 I was able to put together a 75g load with measured velocity of 2600 fps with no signs of excessive pressure. To date my best group with this load is five shots into just under an inch at 100 yards. Frankly, that's about as well as I can shoot with iron sights. In the future I intend to experiment with 60g bullets and slower powders possibly 4198. At this point I am highly satisfied with my little carbine.