Load Specifications
Load data in caliber .257 Weath. Mag. with .257 | 80gr | Impala LWHV LS bullet and 75 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Alliant Reloder-26, Ramshot Grand and Norma MRP.
Important Notice: DO NOT go below Minimum Charge or above Maximum Charge. Since we have no control over the equipment and components used, any responsibility and liability for the results achieved is rejected.
Only powders/loads that match the current filter criteria are displayed: max pressure of a load ≤ 90% of max. standardized pressure, fill rate ≥ 80% and propellant combustion ≥ 95%. Use the sliders above the tables to adjust these thresholds.
Charge: Powder weight in grains. Start with the minimum load and work up carefully.
FR (Fill Rate): Case fill as a percentage. Values above 100% mean compressed loads.
MaxP / %: Maximum chamber pressure in bar and as a percentage of the standardized maximum for this caliber.
V(0): Muzzle velocity in feet per second (fps) at the standardized barrel length.
z (Powder Burn): Estimated propellant combustion percentage at bullet exit.
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Max Load - Barrel Length: 26"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 2700 | <<locked>> | 84% | 55,347 psi | 87% | 3524 fps | 97.9% |
| Accurate 3100 | <<locked>> | 96% | 54,607 psi | 86% | 3583 fps | 99.1% |
| Accurate 4350 | <<locked>> | 88% | 55,680 psi | 87% | 3652 fps | 99.9% |
| ADI AR 2208 | <<locked>> | 84% | 56,420 psi | 88% | 3615 fps | 100% |
| ADI AR 2209 | <<locked>> | 94% | 55,753 psi | 87% | 3675 fps | 97.2% |
| ADI AR 2213 | <<locked>> | 98% | 57,232 psi | 90% | 3730 fps | 96.3% |
| Alliant Reloder- TS 15.5 | <<locked>> | 82% | 54,462 psi | 85% | 3589 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 90% | 55,201 psi | 87% | 3707 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 86% | 56,913 psi | 89% | 3734 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 94% | 55,201 psi | 87% | 3658 fps | 97.2% |
| Alliant Reloder-22 | <<locked>> | 98% | 56,971 psi | 89% | 3734 fps | 97.7% |
| Alliant Reloder-23 | <<locked>> | 98% | 54,288 psi | 85% | 3665 fps | 100% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 50,357 psi | 79% | 3632 fps | 99.3% |
| Alliant Reloder-26 | <<locked>> | 94% | 54,752 psi | 86% | 3757 fps | 99.9% |
| Bofors RP15ᴾ | <<locked>> | 100% | 55,912 psi | 88% | 3707 fps | 97.4% |
| Bofors RP3 | <<locked>> | 82% | 55,956 psi | 88% | 3615 fps | 100% |
| Bofors RP5 | <<locked>> | 98% | 56,971 psi | 89% | 3734 fps | 97.7% |
| Bofors RP7 | <<locked>> | 86% | 54,621 psi | 86% | 3576 fps | 97.9% |
| Hodgdon H380 | <<locked>> | 82% | 55,724 psi | 87% | 3622 fps | 99.7% |
| Hodgdon H414 | <<locked>> | 84% | 54,346 psi | 85% | 3645 fps | 98.4% |
| Hodgdon H4350 | <<locked>> | 88% | 54,389 psi | 85% | 3609 fps | 97.2% |
| Hodgdon Hybrid 100V | <<locked>> | 92% | 56,028 psi | 88% | 3619 fps | 100% |
| Hodgdon LEVERevolution | <<locked>> | 82% | 57,029 psi | 89% | 3668 fps | 100% |
| Hodgdon Retumboᴾ | <<locked>> | 100% | 49,400 psi | 77% | 3671 fps | 96.8% |
| Hodgdon Superformance | <<locked>> | 88% | 57,537 psi | 90% | 3727 fps | 98.7% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 36,738 psi | 58% | 2392 fps | 100% |
| Hodgdon VARGET | <<locked>> | 82% | 55,825 psi | 87% | 3609 fps | 100% |
| IMR 4064 | <<locked>> | 84% | 55,361 psi | 87% | 3589 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 86% | 57,537 psi | 90% | 3615 fps | 98.7% |
| IMR 4350 | <<locked>> | 90% | 55,840 psi | 88% | 3609 fps | 98.2% |
| IMR 4451 Enduron | <<locked>> | 86% | 55,695 psi | 87% | 3602 fps | 98.5% |
| IMR 4831 | <<locked>> | 94% | 56,724 psi | 89% | 3648 fps | 99.9% |
| IMR 7828 SSC | <<locked>> | 96% | 55,274 psi | 87% | 3704 fps | 96% |
| Lovex S062 | <<locked>> | 82% | 56,608 psi | 89% | 3596 fps | 100% |
| Lovex S065 | <<locked>> | 88% | 56,695 psi | 89% | 3609 fps | 99.4% |
| Lovex S070 | <<locked>> | 88% | 54,882 psi | 86% | 3596 fps | 98.6% |
| Lovex S071ᴾ | <<locked>> | 100% | 52,069 psi | 82% | 3533 fps | 98.8% |
| Norma 203B | <<locked>> | 82% | 57,232 psi | 90% | 3658 fps | 100% |
| Norma 204 | <<locked>> | 90% | 56,739 psi | 89% | 3668 fps | 97.3% |
| Norma MRP | <<locked>> | 96% | 56,855 psi | 89% | 3763 fps | 98.8% |
| Norma URP | <<locked>> | 90% | 57,145 psi | 90% | 3688 fps | 99.9% |
| Ramshot Grand | <<locked>> | 94% | 55,100 psi | 86% | 3704 fps | 96.3% |
| Ramshot Hunter | <<locked>> | 90% | 56,086 psi | 88% | 3675 fps | 99.2% |
| Ramshot Magnum | <<locked>> | 98% | 56,579 psi | 89% | 3684 fps | 98.4% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 37,565 psi | 59% | 2448 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 82% | 55,405 psi | 87% | 3593 fps | 98.9% |
| ReloadSwiss RS 60 | <<locked>> | 84% | 56,115 psi | 88% | 3727 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 88% | 55,288 psi | 87% | 3661 fps | 99.8% |
| ReloadSwiss RS 70 | <<locked>> | 90% | 57,145 psi | 90% | 3757 fps | 99.9% |
| ReloadSwiss RS 76ᴾ | <<locked>> | 100% | 50,212 psi | 79% | 3671 fps | 98.2% |
| Rottweil R 903 | <<locked>> | 84% | 55,985 psi | 88% | 3609 fps | 100% |
| Rottweil R 904 | <<locked>> | 94% | 57,217 psi | 90% | 3638 fps | 96.4% |
| Rottweil R 905 | <<locked>> | 94% | 54,679 psi | 86% | 3645 fps | 97.2% |
| Rottweil R 907 | <<locked>> | 86% | 54,621 psi | 86% | 3576 fps | 97.9% |
| Shooters World Long Rifle | <<locked>> | 88% | 56,695 psi | 89% | 3609 fps | 99.4% |
| Shooters World Precision | <<locked>> | 82% | 56,608 psi | 89% | 3596 fps | 100% |
| Shooters World SW4350 | <<locked>> | 88% | 54,882 psi | 86% | 3596 fps | 98.6% |
| SNPE Vectan SP 11 | <<locked>> | 84% | 56,971 psi | 89% | 3661 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 84% | 55,709 psi | 87% | 3468 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 88% | 56,260 psi | 88% | 3543 fps | 98.7% |
| SNPE Vectan Tubal 8000 | <<locked>> | 94% | 54,201 psi | 85% | 3638 fps | 97.1% |
| Somchem S355 | <<locked>> | 84% | 55,724 psi | 87% | 3602 fps | 100% |
| Somchem S365 | <<locked>> | 92% | 57,246 psi | 90% | 3691 fps | 100% |
| Somchem S385 | <<locked>> | 94% | 55,883 psi | 88% | 3622 fps | 98.2% |
| Unknown powder | <<locked>> | 88% | 57,406 psi | 90% | 3688 fps | 99.8% |
| Vihtavuori N150 | <<locked>> | 90% | 57,261 psi | 90% | 3579 fps | 100% |
| Vihtavuori N160 | <<locked>> | 86% | 54,201 psi | 85% | 3583 fps | 99.7% |
| Vihtavuori N165ᴾ | <<locked>> | 100% | 56,623 psi | 89% | 3609 fps | 98% |
| Vihtavuori N550 | <<locked>> | 86% | 55,071 psi | 86% | 3645 fps | 99.8% |
| Vihtavuori N555 | <<locked>> | 96% | 56,898 psi | 89% | 3701 fps | 100% |
| Vihtavuori N560 | <<locked>> | 98% | 57,232 psi | 90% | 3760 fps | 96% |
| Winchester 6.5 StaBALL | <<locked>> | 88% | 55,042 psi | 86% | 3560 fps | 100% |
| Winchester 760 | <<locked>> | 84% | 54,346 psi | 85% | 3645 fps | 98.4% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 54,346 psi | 85% | 3806 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 94% | 57,464 psi | 90% | 3638 fps | 97.6% |
Recommended = one of the top powders for this cartridge and bullet combination.
Start Load - Barrel Length: 26"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 2700 | <<locked>> | 80% | 48,849 psi | 77% | 3392 fps | 96.5% |
| Accurate 3100 | <<locked>> | 86% | 39,378 psi | 62% | 3251 fps | 95.7% |
| Accurate 4350 | <<locked>> | 80% | 42,670 psi | 67% | 3376 fps | 98.2% |
| ADI AR 2208 | <<locked>> | 80% | 49,879 psi | 78% | 3491 fps | 99.6% |
| ADI AR 2209 | <<locked>> | 90% | 49,081 psi | 77% | 3533 fps | 95.6% |
| ADI AR 2213 | <<locked>> | 96% | 53,679 psi | 84% | 3655 fps | 95.4% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 51,242 psi | 80% | 3527 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 80% | 40,248 psi | 63% | 3369 fps | 97.9% |
| Alliant Reloder-17 | <<locked>> | 80% | 46,108 psi | 72% | 3527 fps | 99.9% |
| Alliant Reloder-19 | <<locked>> | 90% | 48,718 psi | 76% | 3524 fps | 95.7% |
| Alliant Reloder-22 | <<locked>> | 92% | 46,760 psi | 73% | 3517 fps | 95.2% |
| Alliant Reloder-23 | <<locked>> | 80% | 30,734 psi | 48% | 3077 fps | 96% |
| Alliant Reloder-25 | <<locked>> | 90% | 36,941 psi | 58% | 3284 fps | 95.4% |
| Alliant Reloder-26 | 62.6 gr | 82% | 35,592 psi | 56% | 3287 fps | 95.7% |
| Bofors RP15 | <<locked>> | 96% | 49,139 psi | 77% | 3570 fps | 95.8% |
| Bofors RP3 | <<locked>> | 80% | 52,286 psi | 82% | 3547 fps | 100% |
| Bofors RP5 | <<locked>> | 92% | 46,760 psi | 73% | 3517 fps | 95.2% |
| Bofors RP7 | <<locked>> | 80% | 45,629 psi | 72% | 3383 fps | 95.8% |
| Hodgdon H380 | <<locked>> | 80% | 52,170 psi | 82% | 3550 fps | 99.4% |
| Hodgdon H414 | <<locked>> | 80% | 47,558 psi | 75% | 3501 fps | 97% |
| Hodgdon H4350 | <<locked>> | 84% | 48,298 psi | 76% | 3481 fps | 95.8% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 38,218 psi | 60% | 3245 fps | 98.6% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 53,316 psi | 84% | 3602 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 98% | 46,354 psi | 73% | 3593 fps | 95.7% |
| Hodgdon Superformance | <<locked>> | 80% | 43,105 psi | 68% | 3419 fps | 95.4% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,528 psi | 43% | 2149 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 52,707 psi | 83% | 3550 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 49,327 psi | 77% | 3468 fps | 99.7% |
| IMR 4166 Enduron | <<locked>> | 80% | 48,124 psi | 75% | 3422 fps | 97% |
| IMR 4350 | <<locked>> | 82% | 43,540 psi | 68% | 3343 fps | 95.2% |
| IMR 4451 Enduron | <<locked>> | 80% | 46,456 psi | 73% | 3409 fps | 96.6% |
| IMR 4831 | <<locked>> | 80% | 36,985 psi | 58% | 3212 fps | 96.7% |
| IMR 7828 SSC | <<locked>> | 94% | 51,808 psi | 81% | 3629 fps | 95% |
| Lovex S062 | <<locked>> | 80% | 53,461 psi | 84% | 3540 fps | 100% |
| Lovex S065 | <<locked>> | 80% | 44,701 psi | 70% | 3360 fps | 97.5% |
| Lovex S070 | <<locked>> | 80% | 43,062 psi | 67% | 3337 fps | 95.9% |
| Lovex S071 | <<locked>> | 90% | 38,101 psi | 60% | 3215 fps | 95.2% |
| Norma 203B | <<locked>> | 80% | 53,824 psi | 84% | 3596 fps | 100% |
| Norma 204 | <<locked>> | 86% | 49,806 psi | 78% | 3524 fps | 95.7% |
| Norma MRP | 65.2 gr | 88% | 43,250 psi | 68% | 3468 fps | 95.7% |
| Norma URP | <<locked>> | 80% | 41,640 psi | 65% | 3356 fps | 97.8% |
| Ramshot Grand | 70.3 gr | 92% | 51,227 psi | 80% | 3622 fps | 95.2% |
| Ramshot Hunter | <<locked>> | 80% | 40,495 psi | 63% | 3330 fps | 95.8% |
| Ramshot Magnum | <<locked>> | 92% | 45,368 psi | 71% | 3448 fps | 95.7% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 28,166 psi | 44% | 2201 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 51,938 psi | 81% | 3524 fps | 98.4% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 48,776 psi | 76% | 3596 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 42,163 psi | 66% | 3383 fps | 97.8% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 40,495 psi | 63% | 3383 fps | 97.1% |
| ReloadSwiss RS 76 | <<locked>> | 96% | 43,801 psi | 69% | 3504 fps | 96.2% |
| Rottweil R 903 | <<locked>> | 80% | 49,414 psi | 77% | 3484 fps | 100% |
| Rottweil R 904 | <<locked>> | 92% | 53,722 psi | 84% | 3570 fps | 95.6% |
| Rottweil R 905 | <<locked>> | 90% | 48,095 psi | 75% | 3507 fps | 95.6% |
| Rottweil R 907 | <<locked>> | 80% | 45,629 psi | 72% | 3383 fps | 95.8% |
| Shooters World Long Rifle | <<locked>> | 80% | 44,701 psi | 70% | 3360 fps | 97.5% |
| Shooters World Precision | <<locked>> | 80% | 53,461 psi | 84% | 3540 fps | 100% |
| Shooters World SW4350 | <<locked>> | 80% | 43,062 psi | 67% | 3337 fps | 95.9% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 50,125 psi | 79% | 3537 fps | 99.9% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 49,313 psi | 77% | 3360 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 43,743 psi | 69% | 3284 fps | 96.1% |
| SNPE Vectan Tubal 8000 | <<locked>> | 90% | 47,674 psi | 75% | 3497 fps | 95.5% |
| Somchem S355 | <<locked>> | 80% | 49,284 psi | 77% | 3481 fps | 99.9% |
| Somchem S365 | <<locked>> | 80% | 38,319 psi | 60% | 3307 fps | 99.6% |
| Somchem S385 | <<locked>> | 86% | 43,192 psi | 68% | 3350 fps | 95.1% |
| Unknown powder | <<locked>> | 80% | 44,411 psi | 70% | 3422 fps | 97.9% |
| Vihtavuori N150 | <<locked>> | 80% | 42,424 psi | 66% | 3291 fps | 99.9% |
| Vihtavuori N160 | <<locked>> | 80% | 44,686 psi | 70% | 3389 fps | 98.5% |
| Vihtavuori N165 | <<locked>> | 94% | 46,789 psi | 73% | 3415 fps | 95.8% |
| Vihtavuori N550 | <<locked>> | 80% | 45,324 psi | 71% | 3442 fps | 98.5% |
| Vihtavuori N555 | <<locked>> | 80% | 34,229 psi | 54% | 3182 fps | 96.2% |
| Vihtavuori N560 | <<locked>> | 96% | 53,693 psi | 84% | 3684 fps | 95.1% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 42,032 psi | 66% | 3304 fps | 99.6% |
| Winchester 760 | <<locked>> | 80% | 47,558 psi | 75% | 3501 fps | 97% |
| Winchester StaBALL HD | <<locked>> | 82% | 29,428 psi | 46% | 3123 fps | 96.2% |
| Winchester Supreme 780 | <<locked>> | 88% | 46,485 psi | 73% | 3419 fps | 95% |
Recommended = one of the top powders for this cartridge and bullet combination.
ᴾ possible press load - work up slowly to this load while watching for signs of excessive pressure.
This overview compares 88 powders for .257 Weath. Mag. loaded with the .257 | 80gr | Impala LWHV LS. Winchester StaBALL HD delivers the highest muzzle velocity at 3,806 fps; across all powders the maximum-charge window runs from 2,392 fps to 3,806 fps. ADI AR 2217 gives the best case fill at 100 %, and 88 of the 88 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (440 MPa), the top charges use 57–90 %, leaving at least 10 % headroom. The 80.0 gr projectile in 0.257" calls for a 1:9.0 twist; slower twists will usually not stabilise this weight. ADI AR 2217, ADI AR 2225, Alliant Reloder-25 reach 100 % fill or more at maximum charge, so these are compressed loads: they need a long drop tube to seat cleanly and react sensitively to the case capacity of your own brass lot. Alliant Reloder-26, Ramshot Grand, Norma MRP rank at the top here: for .257 Weath. Mag. with the .257 | 80gr | Impala LWHV LS they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Accurate MAGPRO, ADI AR 2217, Baschieri & Pellagri 109 burn incompletely and react more sensitively to barrel length and temperature. Always begin at the start load and work up in small increments while checking case and primer for pressure signs.