.270 Winchester

Left to Right 130-grain (8.4 g) - Hollow Point, 100-grain (6.5 g) FMJBT, 130-grain (8.4 g) Soft point, 160-grain (10 g) Lead round nose.

Type

Rifle / Hunting

Place of origin

United States

Production history

Designer

Winchester

Designed

1923

Manufacturer

Winchester

Produced

1925-Present

Specifications

Parent case

.30-06

Bullet diameter

.277 in (7.0 mm)

Neck diameter

.308 in (7.8 mm)

Shoulder diameter

.441 in (11.2 mm)

Base diameter

.470 in (11.9 mm)

Rim diameter

.473 in (12.0 mm)

Case length

2.540 in (64.5 mm)

Overall length

3.340 in (84.8 mm)

Case capacity

67 gr H₂O (4.3 cm³)

Rifling twist

1 in 10 in (250 mm)

Primer type

Large rifle

Maximum pressure

65,000 psi (450 MPa)

Ballistic performance

Bullet mass/type	Velocity	Energy
90 gr (6 g) HP	3,603 ft/s (1,098 m/s)	2,595 ft·lbf (3,518 J)
130 gr (8 g) SP	3,060 ft/s (930 m/s)	2,702 ft·lbf (3,663 J)
140 gr (9 g) SP	2,916 ft/s (889 m/s)	2,644 ft·lbf (3,585 J)
150 gr (10 g) SP	2,850 ft/s (870 m/s)	2,706 ft·lbf (3,669 J)
130 gr (8 g) SST	3,200 ft/s (980 m/s)	2,955 ft·lbf (4,006 J)

Source(s): Hodgdon,Hornady

The .270 Winchester (or 6.9x64mm) was developed by Winchester Repeating Arms Company in 1923 and unveiled in 1925 as a chambering for their bolt-action Model 54. The cartridge is a necked down .30-03, which is the same length as the .280 Remington, both of which are longer than the .30-06 Springfield. The .270, .280, and .30-06 are brothers and the .30-06 is the parent case. When loaded with a bullet that expands rapidly or fragments in tissue, this cartridge delivers devastating terminal performance.

The .270 Winchester became a very popular cartridge due to the widespread praises of gunwriter Jack O'Connor who used the cartridge for 40 years and espoused its merits in the pages of Outdoor Life. It drives an 8.4 grams (130 gr) bullet at approximately 960 m/s (3,140 ft/s), later reduced to 930 m/s (3,060 ft/s). The cartridge demonstrated high performance at the time of its introduction and was marketed as being suitable for big game shooting in the 370 to 910 metres (400 to 1,000 yd) range. Two additional bullet weights were soon introduced: a 6.5 grams (100 gr) hollow-point bullet for varmint shooting, and a 9.7 grams (150 gr) bullet for larger deer, elk, and moose in big-game hunting.

While not an immediate success, over the succeeding decades and especially in the post-World War II period, the .270 Winchester attained great popularity among gun owners and hunters, ranking it among the most popular and widely used cartridges worldwide. Internationally, firearms manufacturers now offer this chambering in all firearm varieties: bolt-actions, single-shots, lever-actions (such as the Browning BLR), pump-actions (such as the Remington 7600), autoloaders (such as the Remington 7400), and even a few double rifles.

...
Wikipedia