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357 Magnum Load Data & Ballistics Calculator

Estimate chamber pressure and muzzle velocity for the 357 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.

357 Magnum reference

Maximum average pressure (MAP)35,000 psi
Nominal case capacity26.5 gr H₂O
Groove / bullet diameter0.355 in (9.02 mm)

Example simulation illustrative

Bullet
Hornady 0.357 158 gr FP-XTP
Powder
Alliant 2400
Charge
11.5 gr
Barrel
4 in

Muzzle velocity

904 fps

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

13,325 – 16,913 – 20,981 psi

nominal is 48% of the 35,000 psi maximum average pressure

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.

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