.270 Winchester

Type: Rifle
Country of Origin: United States
Production History
Designer: Winchester
Designed: 1923
Produced: 1925-Present
Specifications
Case Type: Rimless, bottleneck
Parent Case: .30-06 Springfield
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: 66 gr. H₂O (4.29 cm³)
Rifle Primer: Large Rifle

The .270 Winchester is a rifle round that was developed by Winchester Repeating Arms Company in 1923 and was officially produced in 1925 as a chambering for Winchester's Bolt-Action Model 54. When it was introduced, it offered better long-range performance than any other big game cartridge available in America. This .270 Winchester is based on the .30-06 Springfield cartridge necked down to .277-inch and it is also 0.050-inch longer. Except for these two differences, it is otherwise identical to the .30-06. The .270 Winchester initially gained most of its popularity from a well known gun writer, Jack O'Connor, who praised the cartridge for its outstanding performance. It became a popular hunting cartridge because of its' flat trajectory, long-range performance, and stopping power. It outmatched many of the other hunting cartridges of its time. The .270 Winchester was originally introduced with an 130-grain bullet. Eventually, two additional bullet weights were introduced: a 100-grain hollow point bullet for varmint shooting and a 150-grain larger deer, elk, and moose in big game hunting. This cartridge was not an immediate success, but the popularity of this round increased as time went on, especially in the World War II period. It's high velocity and long range efficiency led to it becoming one of the most widely used cartridges worldwide among gun owners and hunters. Today, the .270 Winchester has been adopted by practically every manufacturer of standard bolt-action, high-powered sporting rifles in the world and it is commercially loaded by all large domestic and foreign ammunition manufacturers. 


Ballistics:


                                                                           Velocity (fps)                                                              Energy (ft.-lbs.)
Bullet Wgt. (grs.)                                  Muzzle  100 yds.  200 yds.  300 yds.  400 yds.           Muzzle  100 yds.  200 yds.  300 yds.  400 yds.
100                                                        3430      3021      2649        2305         1988                 2612     2027       1557        1179         877
115                                                        2710      2482      2265        2059         NA                   1875     1485        1161         896          NA
130                                                        3060      2776      2510        2259         2022                2702     2225        1818         1472        1180
140                                                        2940      2700      2480        2260         2060                2685     2270        1905         1590        1315
150                                                        2850      2585      2336        2100         1879                2705     2226        1817         1468        1175




                                                                              Trajectory (in.)
Bullet Wgt. (grs.)                                  100 yds.   200 yds.   300 yds.   400 yds. 
100                                                        +2.0          +1.0          -4.9          -17.5
115                                                          0.0          +4.8          -17.3           0.0
130                                                        +2.5          +1.4          -5.3           -18.2
140                                                        +2.5          +1.8          -4.6           -17.9
150                                                        +2.5          +1.2          -6.5           -22.0