.264 Winchester Magnum
Date: Dec 24 2014
Notes from the Lab: .264 Winchester Magnum
The .264 Winchester Magnum was first offered in 1958 in the Winchester Model 70 Westerner rifle but was soon offered by most major manufacturers. It was one of four Winchester cartridges that were the original "short magnums" designed to function in a standard (3.340 inch) .30-06 length action. Previous belted magnums, such as the .300 and .375 H&H, required a long action to accommodate their 3.600 inch lengths. The .264 was advertised to push 100-grain bullets to 3,700 fps, or a 140 at 3,200 fps. These velocities were obtained from a 26-inch barrel, but like most factory loads from that era, they were optimistic to say the least. Recent testing of vintage Winchester factory loads in an original Winchester Model 70 rifle with a 26-inch barrel produced 3,066 fps, while today’s factory loads hovered below 3,000 fps.
The .264 Winchester Magnum became an overnight sensation with strong sales, but that soon ended. In 1963 Remington necked the .264 case up to accept .284-inch bullets and called it the 7mm Remington Magnum introduced in the Model 700 rifle. It boasted of greater bullet selection and versatility and all but killed the .264. Today the .264 still has loyal followers and is an excellent, flat-shooting cartridge for hunting deer and pronghorn in open country. With correct bullets, it will reliably take elk, moose, etc. It is still produced in limited quantities from several rifle manufacturers.
The .264 Winchester Magnum has some unusual engineering that handloaders should be aware of. In order to reach desired velocities, Winchester engineered early factory loads with a two diameter bullet. The forward ogive is several thousandths of an inch smaller than the .264-inch diameter shank seated inside the case. The ogive effectively rides the bore, while the shank engages the rifling and fills the grooves in a normal fashion. For this design to work properly, the throat is necessarily short. When using conventional .264/6.5 bullets that are not two diameter, bullets must necessarily be seated deeply to prevent their contacting the leade, which can raise pressures and often results in a bullet being stuck in the bore when extracting a live round from the chamber. Many early Winchester rifles have had their throats lengthened to allow more conventional bullet seating; however, in handloading for rifles produced by other manufacturers there is a notable difference in throat length.
The .264 thrives on slow burning powders such as IMR-4350, IMR-4831, IMR-7828, Alliant RL-22 and others with similar burn rates.