Handloading the .25 WSSM
Date: Mar 01 2011
Being a bit of a fanatic about .25-caliber cartridges, I was more than slightly interested in Winchester Ammunition’s announcement in 2004 of its .25 Winchester Super Short Magnum (WSSM). Winchester stated the stubby cartridge delivered the performance of the .25-06 in an action two sizes smaller, and factory loads certainly lived up to that claim. U.S. Repeating Arms chambered several of its Model 70 rifles in .25 WSSM, and Browning did the same with five models of its A-Bolt rifles that had receivers an inch shorter than standard actions.
I thought the little cartridge was great for hunting coyotes, deer and pronghorn and that it would become fairly popular, but a perfect storm of events killed the cartridge. Internet bloggers shrieked through their keyboards about what terrible cartridges the .223, .243 and .25 super shorts were before these rifles were even stocked on sporting goods store shelves. The cartridges supposedly rapidly burned out barrels and jammed when they made the jump from a rifle’s magazine to the chamber. Production of Model 70 rifles in WSSM calibers abruptly ended when Winchester closed its plant in New Haven, Connecticut, in 2006. When Winchester started making Model 70s again in South Carolina in 2008, the Super Short action was noticeably absent. The loss of a patent infringement lawsuit on the design of the short magnum case also resulted in companies having to pay a royalty on any Winchester Short Magnum and Super Short Magnum ammunition and rifles they sold. The Super Short cartridges were so new they had not become all that popular, so Browning soon dropped its rifles chambered in .223, .243 and .25 WSSM. A very few AR-type rifles are the only ones currently chambered in .25 WSSM.
This is unfortunate, because the .25 WSSM is an excellent cartridge. Its case has about the same propellant capacity as the .257 Roberts, but it is loaded to a much higher maximum pressure of 65,000 psi. The .25 Winchester’s maximum pressure is also higher than the .250 Savage, .257 Improved Ackley and the .25-06 Remington. Thumbing through my handloading records, I came up with the top velocities for a variety of bullet weights for the five .25-caliber cartridges listed in Table I.
The .25 WSSM’s velocities are from my early handloads for the cartridge. Velocities are right in there with the .257 Improved Ackley. However, in the last
few years, new loading data and new propellants and bullets have been introduced that have boosted the .25 WSSM’s velocities and made it an even better hunting cartridge.
The Barnes 100-grain Triple-Shock has worked very well the last few years from an A-Bolt Hunter for hunting pronghorn at long range and whitetails close up in the timber. The Barnes leaves the A-Bolt’s 22-inch barrel at 3,286 fps pushed with 48.5 grains of H-4350. According to the Sierra Infinity ballistics program, the Barnes bullet should drop 1.69 inches at 300 yards if it is sighted 2.50 inches above aim at 100 yards, but the bullet actually hits 2 inches high at 300 yards with that sight setting. I used that flat trajectory to kill a pronghorn at 390 yards on a day of howling wind in Wyoming. The bullet was recovered under the skin on the off-side of the buck, and it had expanded perfectly and still weighed 100 grains.