"Ask the Rabbi" by R. Mermelstein
Shalom!
I would like some information on reloading the .357 SIG. Dies are available, but I have not seen any recipes. Can one use standard 9 mm 124 gr. slugs? Do they need to be jacketed to hold together at the high velocity achieved by this round? How about other slug weights? Which powders are best?
Yours in peace and prosperity,
Peter Lenz
The Sierra Handgun Reloading Manual, 4th Ed., lists loads for the .357 SIG. The singular difficulty in loading for this cartridge is using a suitable 9 mm bullet. Since the maximum overall cartridge length is 1.140-inch, the majority of jacketed 9 mm bullets have such a short full diameter shank that when seated to the correct depth in the SIG case, that area is below the short (.150-inch) case neck. This leaves nothing for the case neck to grip, and the bullet can be pressed down through this neck with mere finger pressure. Much greater impact is exerted on the bullet when a round is stripped from the magazine and the bullet strikes the feed ramp on its way into the chamber. For this reason, Sierra lists only two of their jacketed 9 mm bullets from the seven they manufacture with a sufficiently long shank for the .357 SIG: their 95 gr. FMJ and 115 gr. JHP. Powder selection is no problem, though. From Alliant Unique to AA-No. 9 are all listed in the Sierra manual for the 115 gr. JHP. Western Nevada Bullet Co. (telephone (800)248-3941) makes a far less expensive Total Metal Jacket 124 gr. FP bullet that works extremely well. Load it over 9.0 gr. of Alliant Blue Dot for a very pleasant to shoot target and practice load. Velocity is between 1150-1200 fps. Use standard, not magnum, small pistol primers. I've used Winchester small pistol primers, but Federal or CCI should work equally well. This is not a maximum load. There is no need to start below this load to work up to it. Bullets designed for autoloaders have no cannelure or crimp groove, so use a taper crimp crimping die and don't try to seat and crimp in one operation. This can cause the case mouth to buckle. Also, no carbide sizing dies are available as the .357 SIG bottle neck case design would make the cost prohibitive. Use a good spray case lubricant, such as RCBS Case Slick or Hornady One Shot. Spread the cases flat on a sheet of newspaper without overlapping them, and spray evenly.
Sincerely,
R. Mermelstein
