The 256 Winchester Magnum is nothing more than the 357 Magnum necked down to .257 caliber. It was created in response to Remington’s 22 Jet that used a 357 Magnum case necked to .224 caliber. Both of these bottlenecked cartridges caused issues with the revolvers they were initially intended for, namely, case setback tying up the cylinder upon firing full-power loads. Ruger

addressed the 256 Winchester Magnum issue by releasing the single-shot Hawkeye in 1961. Marlin followed in 1962 with its Model 62 Levermatic lever-action rifle. Both were dandy firearms, but neither these guns nor the 256 Winchester Magnum cartridge grabbed the public’s imagination.

That relegated 256 Winchester Magnum handguns to single shots offered by specialty makers such as Merrill and E. A. Brown, or Thompson/Center’s (T/C) Contender, which was used here for testing. My 256 Winchester Magnum holds a 1970s vintage Contender hexagonal barrel measuring 10 inches long, which comes up 500 to 600 feet per second (fps) short of velocities generated by a rifle-length barrel.

With the 256 Winchester Magnum – despite the superfluous Magnum label borrowed from the parent case – this introduces some obvious bullet expansion issues. It’s a hot 256 Winchester Magnum load that breaks 2,400 fps off the muzzle, so though making hits on small game and varmints at 125 to 150 yards is feasible, few .257-caliber bullets expand well on smaller targets at such ranges. I’ve achieved stellar accuracy with bullets like Sierra’s 70-grain BlitzKing, Hornady’s 75-grain V-MAX and Speer’s 87-grain softpoint, but they tend to zip through small critters with minimal expansion. That is a plus on edible small game such as cottontail rabbits, but not so much on burrowing rodents. This leaves Hornady’s 60-grain FP (Flat Point), which was designed for 25-20 Winchester leverguns and provides the most reliable expansion on small game from this cartridge – the reason I use only this bullet in my 256 Winchester Magnum pistol.

The other real dilemma is that as an essentially obsolete round, load data is scant at best, and what little information is available are loads concocted in the 1960s, with zero experimentation invested since. Hodgdon’s Reloading Center, for instance – normally a treasure-trove of load data for every cartridge imaginable – lists only Hodgdon 110 and 4198 and IMR-4227 as options. My ancient issues of The Complete Reloading Manual for the Thompson/Center Contender, Western Powders Handloading Guide Edition 1, and my Hornady 10th edition Handbook of Cartridge Reloading, offer a few more options, the latter including very low-bulk-density pistol powders (Alliant Unique, Herco and 2400, No. 32, 36 and 54 on my relative burn-rate chart) I find it difficult to take seriously.

My old T/C book includes Hodgdon 4198 and Accurate 2015, No. 76 and 80 on the relative burn rate, with Western Powders adding Accurate 1680 (No. 68). Even if you discard the pistol powders and start with Hodgdon 110 (No. 63), that excludes many more modern options, including Accurate No. 9, Accurate 4100, Vihtavuori N110, Hodgdon Lil’Gun, Alliant Power Pro 300-MP, Accurate No. 11 FS, Alliant Reloder 7 and Hodgdon CFE BLK.

I was determined to fill those gaps and discover additional options that might offer cleaner-burning characteristics and improved temperature stability. I chose 15 powders I believed were suitable, some of them older or proven powders to help form a baseline, others newer options never before auditioned. The newer powders required some very careful extrapolation, cross-referencing relative burn rates and progressing quite conservatively.

Though ready-made, properly headstamped cases can be ordered affordably from Quality Cartridge (about a buck apiece), I formed most cases for this test from Starline 357 Magnum brass. Coming up short, I used vintage Winchester W-W Super cases to load the last four powders. I have had good luck lubing a 357 Magnum case and shoving it into a 256 Winchester Magnum full-length die, but for this test I went through the recommended process, which involved Redding’s Form Die No. 1 and No. 2, 256 Form & Trim die and a Series B 256 Winchester Magnum full-length die set, believing it would result in less stress on the resulting cases and longer life. Little Crow Gunworks’ Ultimate Trim Tool was used to finish cases to a 1.271-inch trim length, followed by mouth chamfering. The resulting necks required no turning for thickness. Be sure to check every case after forming to ensure shoulders are adequately bumped to allow the T/C action to close smoothly.

The resulting Starline cases held an average of 22.5 grains of water when filled completely, lining up perfectly with formed Winchester, Remington and Federal 357 Magnum cases, as well as new Quality Cartridge and the vintage Winchester cases. All hold small primer pockets with Federal Ammunition No. 205 Small Rifle primers chosen for ignition. As established, Hornady’s 60-grain FB bullet served all loads.

I kicked things off with Accurate No. 9 powder, which sits at No. 57 on the relative burn rate chart. Conservative charges of 11.5, 12 and 12.5 grains of this fine ball powder were settled on. The best result came from 12 grains of powder, putting three shots into 1.04 inches at a respectable 2,184 fps at 75 yards. The 12.5-grain charge proved a safe maximum. Accurate 4100 (No. 58) is one I had on hand for the 22 TCM, but it has proven useful in magnum revolver cartridges like the 460 Smith & Wesson and the 22 Hornet, its fine ball makeup making for even metering. Charges of 12, 12.5 and 13 grains were settled upon. A-4100 shot its best group of .86 inch – with a charge of 12 grains of powder, with velocity at just 2,038 fps, while the safe maximum of 13 grains hit 2,249 fps but with lesser accuracy.

Vihtavuori N110 (No. 61) is another 22 Hornet standard, a fine stick powder that usually meters quite uniformly. I’ve used this powder in the 256 before, but kicked up the charges this go-round to 14.5, 15 and 15.5 grains, hoping for more velocity. This proved successful, without resulting in excessive pressure signs. Judging from the excellent combination of velocity and accuracy, N-110 certainly hit a sweet spot with this cartridge. A 14.5-grain charge printed into .71 inch at 2,397 fps, with 15 grains pushing things up to 2,453 fps while maintaining a respectable .84-inch group. I ran things up to 15.5 grains, which seemed a safe maximum load, though accuracy deteriorated.