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25 WSSM Load Data & Ballistics Calculator

Estimate chamber pressure and muzzle velocity for the 25 WSSM with the free, in-browser MyLoads internal ballistics simulator. The figures below are illustrative estimates from a physics model — not a recommended load. Always cross-check a current published loading manual.

25 WSSM reference

Maximum average pressure (MAP)65,000 psi
Nominal case capacity53.0 gr H₂O
Groove / bullet diameter0.257 in (6.53 mm)

Example simulation illustrative

Bullet
Hornady 0.257 117 gr InterLock BTSP
Powder
IMR 4350
Charge
42.5 gr
Barrel
24 in

Muzzle velocity

2,817 fps

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

40,376 – 49,621 – 59,842 psi

nominal is 76% MAP (65,000 psi)

Illustrative example — every figure is an estimate; always confirm your load against a current published manual before loading.

Popular 25 WSSM powders

Powders and bullets handloaders commonly use for the 25 WSSM, drawn from public discussion and listed most common first. They appear as the Popular group in the calculator's pickers. This is not a load recommendation — always check your load against a current published manual.

Popular 25 WSSM bullets

Use MyLoads as a 25 WSSM velocity and pressure calculator: it estimates muzzle velocity, muzzle energy and the full chamber-pressure curve for your own powder, charge and barrel length, compared against the reference facts above.

Open the 25 WSSM in the MyLoads calculator →

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