.270 Winchester
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The .270 Winchester is a rifle cartridge developed by Winchester Repeating Arms Company in 1923, and it was unveiled in 1925 as a chambering for their bolt-action Model 54 to become arguably the flattest ... Wikipedia
Designed: 1923
Case capacity: 67 gr H2O (4.3 cm3)
Case length: 2.540 in (64.5 mm)
Parent case: .30-06 Springfield
Produced: 1925–present
Rifling twist: 1 in 10 in (250 mm)