257 Weatherby Magnum

Handload Data

Warning: Bullet selections are specific, and loads are not valid with substitutions of different bullets of the same weight. Variations in bullet length will alter net case capacity,  pressure and velocity. Primer selection is specific and primer types are not interchangeable. These are maximum loads in my firearms and may be excessive in others. All loads should be reduced by 5% as a starting point for development where cartridges have greater than 40 grains in capacity and 10% for cartridges with less than 40 grain capacity following safe handloading practices as represented in established mainstream reloading manuals. Presentation of these loads does not constitute a solicitation for their use, nor a recommendation.

Cartridge – 257 Weatherby Magnum
Firearm Weatherby Mark V® Ultra Lightweight
Barrel Length 26.00″
Min – Max Case Length 2.549″ +0.000″/-0.020″
Max COL 3.170″
Primer CCI 250
Bullet Diameter 0.258″ +0.0″/-0.003″
Reloading Dies RCBS
Bullet Type  Bullet Weight
Grains
Net H2O
Grains
Capacity
COL” Powder Type Powder Charge
Grains
Muzzle Velocity
fps
Muzzle Energy
ft/lbs
Barnes TTSX 80 79.0 3.170 AA MagPro 77.0 3847 2629
Barnes TTSX 80 79.0 3.170 Alliant Reloder 22 74.0 3883 2679
Barnes TTSX 80 79.0 3.170 IMR 7828 SSC 74.0 3899 2700
Speer SP 87 81.1 3.150 AA MagPro 77.0 3740 2703
Speer SP 87 81.1 3.150 Alliant Reloder 25 76.0 3753 2721
Speer SP 87 81.1 3.150 RS Magnum 79 3713 2663
Barnes TTSX 100 76.6 3.170 Alliant Reloder 25 72.0 3597 2873
Barnes TTSX 100 76.6 3.170 Norma MRP 70.0 3610 2894
Barnes TTSX 100 76.6 3.170 RS Magnum 74.5 3547 2794
Speer SP Hot-Cor 100 79.4 3.150 Alliant Reloder 25 73.5 3591 2864
Speer SP Hot-Cor 100 79.4 3.150 IMR 7828SSC 71.0 3600 2878
Speer SP Hot-Cor 100 79.4 3.150 Norma MRP 71.5 3622 2912
Hornady ELD-X 110 77.5 *3.195 AA MagPro 71.5 3447 2902
Hornady ELD-X 110 77.5 *3.195 Alliant Reloder 25 70.5 3414 2847
Hornady ELD-X 110 77.5 *3.195 RS Magnum 73.0 3390 2807
Nosler Partition 120 77.2 *3.210 AA MagPro 70.0 3331 2957
Nosler Partition 120 77.2 *3.210 Alliant Reloder 25 69.0 3313 2924
Nosler Partition 120 77.2 *3.210 Alliant Reloder 33 78.5 3367 3021
*Exceed recommended cartridge overall length. Check for bullet to rifling leade clearance.

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