.338-378 Weatherby Magnum

Due to the continued popularity of the KT, Weatherby introduced the.338-378 Weatherby Magnum in 1998 to its line of commercial ammunition, using a full-length 2.908" case. Although based on the.338-378 KT, the.338-378 Weatherby Magnum and the KT have different load data and chamber sizes and are not interchangeable.

• Name —.338-378 Weatherby Magnum • Origin — United States • Type — Centerfire/Rifle • Designer — Elmer Keith and Bob Thomson • Design Date — 1963 • Manufacturer — Weatherby • Production Date — 1998 • Parent —.378 Weatherby Magnum • Case Type — Belted, bottleneck • Bullet —.338 • Neck —.361 • Shoulder —.560 • Base —.582 • Rim Dia —.579 • Rim Thick —.059 • Case Length — 2.905 • Length — 3.65 • Case Capacity — 125 • Rifling — 1 in 10 • Primer — Magnum Rifle • Max Pressure — 63817 • Bw1 — 250 • Btype1 — Partition type • Vel1 — 3060 • En1 — 5197 • Bw2 — 225 • Btype2 — Truncated solid • Vel2 — 3180 • En2 — 5052 • Bw3 — 200 • Btype3 — Boat-tail soft point • Vel3 — 3350 • En3 — 4983 • Test Barrel Length — 28 in (71 cm) • Balsrc — Weatherby The.338-378 Weatherby Magnum is based on the.338-378 KT, a wildcat cartridge created by Elmer Keith and R.W. "Bob" Thomson in 1966. The KT is based on the.378 Weatherby Magnum cartridge but is shorter by 1/4" and necked down to a.338 caliber bullet. This design was chosen for elk hunting, using the powders available at the time, such as Hodgdon H-4831. Due to the continued popularity of the KT, Weatherby introduced the.338-378 Weatherby Magnum in 1998 to its line of commercial ammunition, using a full-length 2.908" case. Although based on the.338-378 KT, the.338-378 Weatherby Magnum and the KT have different load data and chamber sizes and are not interchangeable.