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30-378 Weatherby Magnum Load Data & Ballistics Calculator

Estimate chamber pressure and muzzle velocity for the 30-378 Weatherby Magnum with the free, in-browser MyLoads internal-ballistics simulator. The figures below are illustrative estimates from a physics model — not a recommended recipe. Always cross-check a current published loading manual.

30-378 Weatherby Magnum reference

Maximum average pressure (MAP)4,400 BAR
Nominal case capacity130.0 gr H₂O
Groove / bullet diameter0.308 in (7.82 mm)

Example simulation illustrative

Bullet
Hornady 0.308 178 gr BTHP Match
Powder
Hodgdon Us 869
Charge
107.4 gr
Barrel
26 in

Muzzle velocity

3,151 fps

Peak chamber pressure (interval, ±10% burn-rate)

40,023 – 55,532 – 74,076 psi

nominal is 87% of the 63,817 psi maximum average pressure

This sample load runs near the maximum average pressure for the 30-378 Weatherby Magnum (about 87% of MAP at the nominal estimate; the upper interval can exceed it). It is shown only to illustrate the simulator — reduce the charge and work up from your manual's start load.

Illustrative example — every figure here is an estimate and can be wrong. Always consult a current published loading manual, and never trust these numbers on their own.

Open the 30-378 Weatherby Magnum in the MyLoads calculator →

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