Load Specifications
Load data in caliber .257 Weath. Mag. with .257 | 80gr | Peregrine VLR-4 bullet and 83 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Norma MRP, ReloadSwiss RS 70 and Alliant Reloder-26.
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.
A valid access license is required to use the Personalized Load Calculator.
You can find more information in our FAQ: How can I use the Personalized Load Calculator?
Max Load - Barrel Length: 26"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 2495 | <<locked>> | 82% | 57,334 psi | 90% | 3550 fps | 100% |
| Accurate 2700 | <<locked>> | 86% | 56,449 psi | 88% | 3560 fps | 98.2% |
| Accurate 3100 | <<locked>> | 98% | 54,549 psi | 85% | 3596 fps | 99.2% |
| Accurate 4064 | <<locked>> | 82% | 54,288 psi | 85% | 3556 fps | 100% |
| Accurate 4350 | <<locked>> | 90% | 55,767 psi | 87% | 3668 fps | 99.9% |
| ADI AR 2208 | <<locked>> | 86% | 57,667 psi | 90% | 3652 fps | 100% |
| ADI AR 2209 | <<locked>> | 96% | 57,174 psi | 90% | 3714 fps | 97.6% |
| Alliant Reloder- TS 15.5 | <<locked>> | 84% | 55,085 psi | 86% | 3615 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 82% | 55,332 psi | 87% | 3645 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 92% | 56,376 psi | 88% | 3740 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 86% | 54,230 psi | 85% | 3701 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 96% | 56,376 psi | 88% | 3694 fps | 97.6% |
| Alliant Reloder-22 | <<locked>> | 98% | 54,157 psi | 85% | 3688 fps | 97.3% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 54,766 psi | 86% | 3681 fps | 100% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 47,514 psi | 74% | 3583 fps | 98.9% |
| Alliant Reloder-26 | <<locked>> | 96% | 55,579 psi | 87% | 3776 fps | 100% |
| Bofors RP15ᴾ | <<locked>> | 100% | 53,069 psi | 83% | 3665 fps | 96.9% |
| Bofors RP3 | <<locked>> | 84% | 56,057 psi | 88% | 3632 fps | 100% |
| Bofors RP5 | <<locked>> | 98% | 54,157 psi | 85% | 3688 fps | 97.3% |
| Bofors RP7 | <<locked>> | 88% | 55,477 psi | 87% | 3606 fps | 98.1% |
| Hodgdon H380 | <<locked>> | 84% | 56,492 psi | 89% | 3652 fps | 99.8% |
| Hodgdon H414 | <<locked>> | 86% | 55,361 psi | 87% | 3678 fps | 98.6% |
| Hodgdon H4350 | <<locked>> | 90% | 55,521 psi | 87% | 3648 fps | 97.6% |
| Hodgdon Hybrid 100V | <<locked>> | 94% | 56,956 psi | 89% | 3645 fps | 100% |
| Hodgdon LEVERevolution | <<locked>> | 82% | 54,288 psi | 85% | 3635 fps | 100% |
| Hodgdon Superformance | <<locked>> | 88% | 54,969 psi | 86% | 3691 fps | 98.4% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 36,376 psi | 57% | 2398 fps | 100% |
| Hodgdon VARGET | <<locked>> | 84% | 57,072 psi | 89% | 3642 fps | 100% |
| IMR 3031 | <<locked>> | 82% | 56,333 psi | 88% | 3619 fps | 100% |
| IMR 4064 | <<locked>> | 86% | 56,449 psi | 88% | 3625 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 86% | 55,230 psi | 87% | 3586 fps | 98.5% |
| IMR 4350 | <<locked>> | 92% | 56,898 psi | 89% | 3645 fps | 98.4% |
| IMR 4451 Enduron | <<locked>> | 88% | 57,072 psi | 89% | 3645 fps | 98.7% |
| IMR 4831 | <<locked>> | 96% | 57,261 psi | 90% | 3671 fps | 100% |
| IMR 4895 | <<locked>> | 82% | 56,797 psi | 89% | 3681 fps | 100% |
| IMR 7828 SSC | <<locked>> | 98% | 56,637 psi | 89% | 3743 fps | 96.4% |
| Lovex S062 | <<locked>> | 84% | 57,188 psi | 90% | 3622 fps | 100% |
| Lovex S065 | <<locked>> | 90% | 57,392 psi | 90% | 3638 fps | 99.6% |
| Lovex S070 | <<locked>> | 90% | 55,390 psi | 87% | 3622 fps | 98.7% |
| Lovex S071ᴾ | <<locked>> | 100% | 48,211 psi | 76% | 3471 fps | 98.2% |
| Norma 203B | <<locked>> | 82% | 54,636 psi | 86% | 3625 fps | 100% |
| Norma 204 | <<locked>> | 90% | 54,172 psi | 85% | 3629 fps | 96.8% |
| Norma MRP | <<locked>> | 96% | 53,867 psi | 84% | 3720 fps | 98.5% |
| Norma URP | <<locked>> | 90% | 54,331 psi | 85% | 3645 fps | 99.8% |
| Ramshot Big Game | <<locked>> | 82% | 55,651 psi | 87% | 3648 fps | 100% |
| Ramshot Grand | <<locked>> | 96% | 56,666 psi | 89% | 3750 fps | 96.9% |
| Ramshot Hunter | <<locked>> | 92% | 57,159 psi | 90% | 3707 fps | 99.4% |
| Ramshot Magnum | <<locked>> | 98% | 53,751 psi | 84% | 3642 fps | 98% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 36,883 psi | 58% | 2448 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 84% | 56,304 psi | 88% | 3625 fps | 99.1% |
| ReloadSwiss RS 60 | <<locked>> | 86% | 57,595 psi | 90% | 3763 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 90% | 55,956 psi | 88% | 3684 fps | 99.8% |
| ReloadSwiss RS 70 | <<locked>> | 90% | 54,331 psi | 85% | 3717 fps | 99.8% |
| ReloadSwiss RS 76ᴾ | <<locked>> | 100% | 47,253 psi | 74% | 3612 fps | 97.6% |
| Rottweil R 902 | <<locked>> | 82% | 55,506 psi | 87% | 3579 fps | 100% |
| Rottweil R 903 | <<locked>> | 86% | 56,405 psi | 88% | 3632 fps | 100% |
| Rottweil R 904 | <<locked>> | 94% | 54,737 psi | 86% | 3606 fps | 96% |
| Rottweil R 905 | <<locked>> | 96% | 55,680 psi | 87% | 3678 fps | 97.5% |
| Rottweil R 907 | <<locked>> | 88% | 55,477 psi | 87% | 3606 fps | 98.1% |
| Shooters World Long Rifle | <<locked>> | 90% | 57,392 psi | 90% | 3638 fps | 99.6% |
| Shooters World Precision | <<locked>> | 84% | 57,188 psi | 90% | 3622 fps | 100% |
| Shooters World SW4350 | <<locked>> | 90% | 55,390 psi | 87% | 3622 fps | 98.7% |
| SNPE Vectan SP 11 | <<locked>> | 84% | 54,433 psi | 85% | 3632 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 86% | 56,913 psi | 89% | 3501 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 90% | 57,334 psi | 90% | 3579 fps | 98.9% |
| SNPE Vectan Tubal 8000 | <<locked>> | 96% | 55,216 psi | 87% | 3671 fps | 97.4% |
| Somchem S355 | <<locked>> | 86% | 56,130 psi | 88% | 3625 fps | 100% |
| Somchem S365 | <<locked>> | 92% | 54,143 psi | 85% | 3652 fps | 100% |
| Somchem S385 | <<locked>> | 96% | 56,536 psi | 89% | 3652 fps | 98.4% |
| Unknown powder | <<locked>> | 88% | 54,824 psi | 86% | 3655 fps | 99.6% |
| Vihtavuori N133 | <<locked>> | 82% | 55,419 psi | 87% | 3481 fps | 100% |
| Vihtavuori N135 | <<locked>> | 82% | 55,869 psi | 88% | 3537 fps | 100% |
| Vihtavuori N140 | <<locked>> | 82% | 55,550 psi | 87% | 3540 fps | 100% |
| Vihtavuori N150 | <<locked>> | 90% | 54,302 psi | 85% | 3543 fps | 100% |
| Vihtavuori N160 | <<locked>> | 88% | 55,274 psi | 87% | 3615 fps | 99.8% |
| Vihtavuori N165ᴾ | <<locked>> | 100% | 53,896 psi | 84% | 3573 fps | 97.6% |
| Vihtavuori N540 | <<locked>> | 82% | 55,477 psi | 87% | 3566 fps | 100% |
| Vihtavuori N550 | <<locked>> | 88% | 55,666 psi | 87% | 3668 fps | 99.8% |
| Vihtavuori N555 | <<locked>> | 98% | 57,276 psi | 90% | 3717 fps | 100% |
| Winchester 6.5 StaBALL | <<locked>> | 90% | 56,478 psi | 89% | 3593 fps | 100% |
| Winchester 760 | <<locked>> | 86% | 55,361 psi | 87% | 3678 fps | 98.6% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 51,343 psi | 80% | 3757 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 94% | 54,752 psi | 86% | 3602 fps | 97.2% |
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 2495 | <<locked>> | 80% | 53,679 psi | 84% | 3494 fps | 100% |
| Accurate 2700 | <<locked>> | 80% | 46,093 psi | 72% | 3350 fps | 95.9% |
| Accurate 3100 | <<locked>> | 88% | 38,203 psi | 60% | 3235 fps | 95.3% |
| Accurate 4064 | <<locked>> | 80% | 50,850 psi | 80% | 3494 fps | 100% |
| Accurate 4350 | <<locked>> | 80% | 39,015 psi | 61% | 3301 fps | 97.2% |
| ADI AR 2208 | <<locked>> | 80% | 47,630 psi | 75% | 3458 fps | 99.4% |
| ADI AR 2209 | <<locked>> | 90% | 46,543 psi | 73% | 3494 fps | 95% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 48,428 psi | 76% | 3488 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 80% | 51,648 psi | 81% | 3573 fps | 99.8% |
| Alliant Reloder-16 | <<locked>> | 80% | 37,710 psi | 59% | 3314 fps | 97.2% |
| Alliant Reloder-17 | <<locked>> | 80% | 43,265 psi | 68% | 3474 fps | 99.6% |
| Alliant Reloder-19 | <<locked>> | 90% | 46,151 psi | 72% | 3478 fps | 95% |
| Alliant Reloder-22 | <<locked>> | 94% | 47,065 psi | 74% | 3537 fps | 95.4% |
| Alliant Reloder-23 | <<locked>> | 82% | 29,718 psi | 47% | 3061 fps | 95.4% |
| Alliant Reloder-25 | <<locked>> | 92% | 36,376 psi | 57% | 3281 fps | 95.2% |
| Alliant Reloder-26 | 65 gr | 84% | 34,809 psi | 55% | 3278 fps | 95.3% |
| Bofors RP15 | <<locked>> | 96% | 46,398 psi | 73% | 3520 fps | 95.1% |
| Bofors RP3 | <<locked>> | 80% | 48,863 psi | 77% | 3497 fps | 100% |
| Bofors RP5 | <<locked>> | 94% | 47,065 psi | 74% | 3537 fps | 95.4% |
| Bofors RP7 | <<locked>> | 80% | 42,699 psi | 67% | 3327 fps | 95% |
| Hodgdon H380 | <<locked>> | 80% | 49,371 psi | 77% | 3510 fps | 99.1% |
| Hodgdon H414 | <<locked>> | 80% | 44,657 psi | 70% | 3448 fps | 96.3% |
| Hodgdon H4350 | <<locked>> | 84% | 45,818 psi | 72% | 3438 fps | 95.1% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 35,186 psi | 55% | 3179 fps | 97.8% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 50,865 psi | 80% | 3573 fps | 100% |
| Hodgdon Superformance | <<locked>> | 82% | 43,555 psi | 68% | 3445 fps | 95.6% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,050 psi | 42% | 2156 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 50,212 psi | 79% | 3517 fps | 100% |
| IMR 3031 | <<locked>> | 80% | 52,924 psi | 83% | 3563 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 46,702 psi | 73% | 3432 fps | 99.4% |
| IMR 4166 Enduron | <<locked>> | 80% | 45,876 psi | 72% | 3389 fps | 96.6% |
| IMR 4350 | <<locked>> | 84% | 43,961 psi | 69% | 3373 fps | 95.5% |
| IMR 4451 Enduron | <<locked>> | 80% | 44,179 psi | 69% | 3369 fps | 96% |
| IMR 4831 | <<locked>> | 80% | 33,866 psi | 53% | 3140 fps | 95.5% |
| IMR 4895 | <<locked>> | 80% | 52,997 psi | 83% | 3612 fps | 100% |
| IMR 7828 SSC | <<locked>> | 96% | 52,649 psi | 83% | 3661 fps | 95.4% |
| Lovex S062 | <<locked>> | 80% | 50,328 psi | 79% | 3501 fps | 100% |
| Lovex S065 | <<locked>> | 80% | 41,771 psi | 65% | 3307 fps | 96.8% |
| Lovex S070 | <<locked>> | 80% | 40,016 psi | 63% | 3274 fps | 95% |
| Lovex S071 | <<locked>> | 94% | 39,378 psi | 62% | 3268 fps | 95.8% |
| Norma 203B | <<locked>> | 80% | 50,995 psi | 80% | 3556 fps | 99.9% |
| Norma 204 | <<locked>> | 86% | 47,224 psi | 74% | 3481 fps | 95% |
| Norma MRP | 67.6 gr | 90% | 43,221 psi | 68% | 3481 fps | 95.8% |
| Norma URP | <<locked>> | 80% | 38,711 psi | 61% | 3297 fps | 97% |
| Ramshot Big Game | <<locked>> | 80% | 51,953 psi | 81% | 3579 fps | 99.9% |
| Ramshot Grand | <<locked>> | 94% | 52,272 psi | 82% | 3658 fps | 95.7% |
| Ramshot Hunter | <<locked>> | 82% | 40,466 psi | 63% | 3346 fps | 95.9% |
| Ramshot Magnum | <<locked>> | 94% | 45,600 psi | 71% | 3468 fps | 95.9% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 27,572 psi | 43% | 2205 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 49,197 psi | 77% | 3484 fps | 98% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 45,977 psi | 72% | 3547 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 39,073 psi | 61% | 3317 fps | 96.9% |
| ReloadSwiss RS 70 | 61.4 gr | 80% | 37,840 psi | 59% | 3320 fps | 96.2% |
| ReloadSwiss RS 76 | <<locked>> | 98% | 43,743 psi | 69% | 3517 fps | 96.3% |
| Rottweil R 902 | <<locked>> | 80% | 52,069 psi | 82% | 3517 fps | 100% |
| Rottweil R 903 | <<locked>> | 80% | 46,006 psi | 72% | 3432 fps | 99.8% |
| Rottweil R 904 | <<locked>> | 92% | 51,271 psi | 80% | 3537 fps | 95.1% |
| Rottweil R 905 | <<locked>> | 92% | 48,414 psi | 76% | 3527 fps | 95.8% |
| Rottweil R 907 | <<locked>> | 80% | 42,699 psi | 67% | 3327 fps | 95% |
| Shooters World Long Rifle | <<locked>> | 80% | 41,771 psi | 65% | 3307 fps | 96.8% |
| Shooters World Precision | <<locked>> | 80% | 50,328 psi | 79% | 3501 fps | 100% |
| Shooters World SW4350 | <<locked>> | 80% | 40,016 psi | 63% | 3274 fps | 95% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 47,413 psi | 74% | 3494 fps | 99.7% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 46,978 psi | 74% | 3330 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 40,857 psi | 64% | 3232 fps | 95.2% |
| SNPE Vectan Tubal 8000 | <<locked>> | 92% | 47,993 psi | 75% | 3520 fps | 95.7% |
| Somchem S355 | <<locked>> | 80% | 46,253 psi | 72% | 3435 fps | 99.8% |
| Somchem S365 | <<locked>> | 80% | 35,172 psi | 55% | 3238 fps | 99% |
| Somchem S385 | <<locked>> | 88% | 43,076 psi | 68% | 3366 fps | 95.2% |
| Unknown powder | <<locked>> | 80% | 41,626 psi | 65% | 3366 fps | 97.3% |
| Vihtavuori N133 | <<locked>> | 80% | 52,214 psi | 82% | 3428 fps | 100% |
| Vihtavuori N135 | <<locked>> | 80% | 52,547 psi | 82% | 3484 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 52,098 psi | 82% | 3481 fps | 100% |
| Vihtavuori N150 | <<locked>> | 80% | 39,610 psi | 62% | 3241 fps | 99.6% |
| Vihtavuori N160 | <<locked>> | 80% | 41,843 psi | 66% | 3337 fps | 97.9% |
| Vihtavuori N165 | <<locked>> | 94% | 44,048 psi | 69% | 3369 fps | 95.1% |
| Vihtavuori N540 | <<locked>> | 80% | 51,851 psi | 81% | 3504 fps | 100% |
| Vihtavuori N550 | <<locked>> | 80% | 42,540 psi | 67% | 3389 fps | 97.9% |
| Vihtavuori N555 | <<locked>> | 82% | 32,982 psi | 52% | 3156 fps | 95.6% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 39,523 psi | 62% | 3258 fps | 99.3% |
| Winchester 760 | <<locked>> | 80% | 44,657 psi | 70% | 3448 fps | 96.3% |
| Winchester StaBALL HD | <<locked>> | 84% | 28,311 psi | 44% | 3087 fps | 95.4% |
| Winchester Supreme 780 | <<locked>> | 90% | 47,007 psi | 74% | 3445 fps | 95.3% |
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 97 powders for .257 Weath. Mag. loaded with the .257 | 80gr | Peregrine VLR-4. Alliant Reloder-26 delivers the highest muzzle velocity at 3,776 fps; across all powders the maximum-charge window runs from 2,398 fps to 3,776 fps. ADI AR 2217 gives the best case fill at 100 %, and 97 of the 97 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 1:9.5 twist; slower twists will usually not stabilise this weight. ADI AR 2217, ADI AR 2225, Alliant Reloder-23 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. Norma MRP, ReloadSwiss RS 70, Alliant Reloder-26 rank at the top here: for .257 Weath. Mag. with the .257 | 80gr | Peregrine VLR-4 they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Accurate MAGPRO, ADI AR 2217, ADI AR 2225 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.