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Reloading .357 Mag

The famous .357 Magnum, the original magnum pistol cartridge, was introduced in 1935 by Smith & Wesson as the world's most powerful handgun cartridge. For over 20 years it was simply known as "the Magnum," as there was no other. Newer magnum cartridges eventually surpassed it in power, but not in popularity or usefulness. The .357 remains the best selling of all magnum handgun cartridges and among the top 10 best selling handgun cartridges.Any .357 Magnum revolver can also shoot all .38 Special ammunition. .38 Special +P loads make particularly good practice ammunition and with 125 grain bullets shoot sufficiently flat for small game hunting.

.357 Magnum factory ballistics tables call for a muzzle velocity of 1450 fps for the 125 grain JHP with 583 ft. lbs. of muzzle energy. For the 140 grain JHP the MV is 1360 fps and the ME is 575 ft. lbs. For the 158 grain JHP the MV is 1235 fps and the ME is 535 ft. lbs. These figures are all for a 4" revolver barrel.

I have been reloading the .357 Magnum since the middle 1960's. I have found Winchester W231 and Hodgdon HS-6 powders excellent for low and medium velocity loads and H-110, W296 and Hercules 2400 powders excellent for maximum loads with bullets weighing from 125-158 grains.

The various 125-129 grain bullets are the top choices for personal defense against "bad guys", but have not provided top accuracy in my .357 handguns. I have found the 140-146 grain bullets to be a good all-around choice for use in the field and very accurate. The heavy 158-180 grain bullets are the ticket for many big game hunting applications and for defense in the field (against large predators).

The Handgun Reloading section of the Speer Reloading Manual Number 14 shows that 16.5 grains of 2400 powder will drive their 125 grain bullets to a MV of 1335 fps, and 17.5 grains of 2400 will drive the same bullets to a MV of 1409 fps.

The 140 grain bullet can be driven to a MV of 1005 fps by 8.8 grains of HS6 powder, or 1142 fps by 9.8 grains of HS-6. I have found these to be useful practice and small game loads.

On the other hand, 16.2 grains of H110 powder will drive the 140 grain bullet to a MV of 1323 fps, and a maximum load of 17.2 grains of H110 will drive the same bullet to a MV of 1352 fps. These are good full power hunting loads.

For heavy loads, the Speer Reloading Manual shows that 13.9 grains of H110 will drive their 158 grain bullets to a MV of 1151 fps, and 15.5 grains of H110 will drive those bullets to a MV of 1217 fps. These Speer velocities were measured in a 6" S&W revolver barrel using Speer cases and CCI primers.