.257 Weatherby Magnum
- Bullet diameter
- 6.53 mm
- Case length
- 64.64 mm
- Max pressure
- 448 MPa
- Introduced
- 1944
Specification
Everything measured
IdentityWhat it is, who designed it and what else it is called.
- Cartridge type
- Belted
- Introduced
- 1944
- Designer
- Roy Weatherby
- Parent cartridge
- 375-hh-magnum
- Also known as
- .257 WM, .257 Wby Mag, .257 Weatherby
DimensionsThe case and the bullet, to a hundredth of a millimetre.
- Bullet diameter
- 6.53 mm
- Neck diameter
- 7.19 mm
- Shoulder diameter
- 12.50 mm
- Base diameter
- 13.00 mm
- Rim diameter
- 13.50 mm
- Rim thickness
- 1.30 mm
- Case length
- 64.64 mm
- Overall length
- 81.51 mm
BallisticsWhat a typical load does, and the pressure it runs at.
- Max pressure
- 448 MPa
- Max pressure, psi
- 65,000
- Typical bullet weight
- 6.48 g
- Typical muzzle velocity
- 1140 m/s
- Typical muzzle energy
- 4210 J
ConstructionWhat the case, primer and projectile are made of and shaped like.
- Case shape
- Bottleneck
- Case material
- Brass
- Primer
- Large rifle magnum
- Projectile
- Bullet
- Bullet profile
- Spitzer
- Mouth closure
- Bullet
- Specification standard
- proprietary
Documentation
Working with cartridge data
This page is one record. These are about the endpoint behind it.
- API referenceEvery cartridge endpoint, its parameters and what it returns.
- SDK methodsThe same calls in JavaScript and Python, with working examples.
- Reading ballisticsWhich figures are measured, which are typical, and how to compare loads.
- Data qualityHow complete the cartridge records are, and where the figures come from.
Provenance
Where these figures came from
Every figure above was taken from one of these pages. The confidence reflects how much of the record came from a page a claim can be checked against.
Confidence in this record
90%
API
The call that returns this record
The same fields, in the same units, from the same endpoint the page reads.
curl --request GET \ --url 'https://api.gunspec.io/v1/calibers/257-weatherby-magnum' \ --header 'X-API-Key: your_key'