.264 Winchester Magnum

Type

Rifle

Place of origin

United States

Production history

Designer

Winchester

Designed

1959

Manufacturer

Winchester

Specifications

Bullet diameter

.264 in (6.7 mm)

Neck diameter

.299 in (7.6 mm)

Shoulder diameter

.491 in (12.5 mm)

Base diameter

.515 in (13.1 mm)

Rim diameter

.532 in (13.5 mm)

Case length

2.5 in (64 mm)

Overall length

3.34 in (85 mm)

Rifling twist

1:9

Primer type

Large rifle

Maximum pressure

64,000 psi (440 MPa)

Ballistic performance

Bullet mass/type	Velocity	Energy
100 gr (6 g) Nosler Ballistic Tip	3,510 ft/s (1,070 m/s)	2,735 ft·lbf (3,708 J)
125 gr (8 g) Nosler Partition	3,180 ft/s (970 m/s)	2,806 ft·lbf (3,804 J)
140 gr (9 g) BTSP	3,200 ft/s (980 m/s)	3,183 ft·lbf (4,316 J)

Source(s): Terminal Ballistics Research

The .264 Winchester Magnum is a belted, bottlenecked rifle cartridge. Apart from the .244 H&H Magnum and .257 Weatherby Magnum, it is the smallest caliber factory cartridge derived from the 2.85 in (72 mm) Holland & Holland belted magnum case. It was introduced in the late 1950s and early 1960s with the .338 Winchester Magnum and the .458 Winchester Magnum as one of a family of short-cased 2.5 in (64 mm) belted magnum cartridges developed by Winchester based on the .375 Holland & Holland parent case. It was officially introduced to the public by Winchester in 1959. After many years of dwindling use it began enjoying a mild resurgence in popularity in the mid-2000s among long range rifle enthusiasts and reloaders due to the high ballistic coefficient of the heavier 6.5mm bullets and increasing popularity of cartridges such as 6.5mm Creedmoor, .260 Remington, 6.5 Grendel, benchrest and wildcat cartridges in 6.5mm.

Winchester had been manufacturing the shortened Holland & Holland cases under a contract for Weatherby for use in their .257 Weatherby Magnum, .270 Weatherby Magnum and 7mm Weatherby Magnum cartridges. The Weatherby cases had been based on Winchester's .30 Super cartridge. This new series of shortened Holland & Holland cases was based on the .375 Holland & Holland case. The advantages of the shortened case were twofold: the cartridge could function through the standard length rifle action as used by the popular .30-06 Springfield and .270 Winchester. It was also close to the efficiency limitations of powders available at the time given the case capacity of the cartridge. The longer, full length .375 H&H case would not have resulted in a great performance improvement due the powders available at that time. It was similar to the reasoning behind the shortened cases used by Weatherby as DuPont's IMR 4350 was the slowest burning powder available then.

...
Wikipedia