Load Specifications
Bullet:.257 | 100gr | Osprey Virtus
Bullet Manufacturer:Virtus
Bullet Weight:100 gr
Bullet Diameter:0.257"
Bullet Length:<<locked>>
Caliber:.25 WSSM load data
Case Length (l3):1.67"
Cartridge Length (C.O.L.):<<locked>>
Case Capacity:54.3 Grains of Water
Primer Size:Large Rifle (LR)
Barrel Length:24"
Max. allowed Pressure:63,817 psi
Recommended Twist Rate:1:10.0
Load data in caliber .25 WSSM with .257 | 100gr | Osprey Virtus bullet and 102 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Alliant Power Pro 2000-MR, ReloadSwiss RS 60 and ReloadSwiss RS 52.
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: 24"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 2015 | <<locked>> | 88% | 56,478 psi | 89% | 3005 fps | 100% |
| Accurate 2460 | <<locked>> | 84% | 54,955 psi | 86% | 3031 fps | 100% |
| Accurate 2495 | <<locked>> | 92% | 54,085 psi | 85% | 3018 fps | 100% |
| Accurate 2520 | <<locked>> | 88% | 55,419 psi | 87% | 3084 fps | 100% |
| Accurate 4064 | <<locked>> | 94% | 54,143 psi | 85% | 3064 fps | 100% |
| Accurate 4350ᴾ | <<locked>> | 100% | 50,314 psi | 79% | 3074 fps | 98.3% |
| Accurate LT-30 | <<locked>> | 82% | 55,883 psi | 88% | 2953 fps | 100% |
| Accurate LT-32 | <<locked>> | 82% | 56,289 psi | 88% | 2979 fps | 100% |
| ADI AR 2206H | <<locked>> | 90% | 55,738 psi | 87% | 3104 fps | 99.6% |
| ADI AR 2208 | <<locked>> | 96% | 57,145 psi | 90% | 3104 fps | 99.4% |
| ADI AR 2219 | <<locked>> | 82% | 56,956 psi | 89% | 3077 fps | 100% |
| ADI Benchmark 8208 | <<locked>> | 88% | 54,882 psi | 86% | 3058 fps | 99.9% |
| Alliant AR-Comp | <<locked>> | 88% | 55,463 psi | 87% | 3041 fps | 100% |
| Alliant Power Pro 1200-R | <<locked>> | 84% | 56,521 psi | 89% | 3173 fps | 99.9% |
| Alliant Power Pro 2000-MR | <<locked>> | 92% | 55,622 psi | 87% | 3225 fps | 99.4% |
| Alliant Reloder- TS 15.5 | <<locked>> | 96% | 56,420 psi | 88% | 3123 fps | 99.9% |
| Alliant Reloder-10x | <<locked>> | 84% | 56,217 psi | 88% | 3015 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 94% | 57,203 psi | 90% | 3146 fps | 99.5% |
| Alliant Reloder-16ᴾ | <<locked>> | 100% | 49,211 psi | 77% | 3081 fps | 98.4% |
| Alliant Reloder-17ᴾ | <<locked>> | 100% | 57,711 psi | 90% | 3255 fps | 100% |
| Baschieri & Pellagri 106 | <<locked>> | 82% | 55,129 psi | 86% | 2943 fps | 100% |
| Baschieri & Pellagri 107 | <<locked>> | 90% | 55,941 psi | 88% | 3120 fps | 99.1% |
| Bofors RP3 | <<locked>> | 96% | 57,174 psi | 90% | 3143 fps | 100% |
| Bofors RP7ᴾ | <<locked>> | 100% | 57,725 psi | 90% | 3100 fps | 96.4% |
| Hodgdon Benchmark | <<locked>> | 88% | 56,898 psi | 89% | 3045 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 88% | 54,128 psi | 85% | 3087 fps | 100% |
| Hodgdon CFE223 | <<locked>> | 86% | 56,188 psi | 88% | 3189 fps | 99.5% |
| Hodgdon H322 | <<locked>> | 84% | 55,695 psi | 87% | 3061 fps | 100% |
| Hodgdon H335 | <<locked>> | 84% | 56,913 psi | 89% | 3084 fps | 100% |
| Hodgdon H380 | <<locked>> | 94% | 54,621 psi | 86% | 3091 fps | 98.5% |
| Hodgdon H414ᴾ | <<locked>> | 100% | 54,056 psi | 85% | 3136 fps | 96.5% |
| Hodgdon H4895 | <<locked>> | 90% | 56,246 psi | 88% | 3117 fps | 99.9% |
| Hodgdon Hybrid 100Vᴾ | <<locked>> | 100% | 45,179 psi | 71% | 2953 fps | 98.8% |
| Hodgdon LEVERevolution | <<locked>> | 92% | 55,825 psi | 87% | 3153 fps | 100% |
| Hodgdon Superformanceᴾ | <<locked>> | 100% | 55,651 psi | 87% | 3176 fps | 96.2% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 34,896 psi | 55% | 1890 fps | 100% |
| Hodgdon VARGET | <<locked>> | 90% | 54,360 psi | 85% | 3068 fps | 99.7% |
| IMR 3031 | <<locked>> | 90% | 56,086 psi | 88% | 3107 fps | 100% |
| IMR 4064 | <<locked>> | 94% | 56,463 psi | 88% | 3087 fps | 99.5% |
| IMR 4166 Enduron | <<locked>> | 92% | 56,811 psi | 89% | 3061 fps | 96.8% |
| IMR 4198 | <<locked>> | 84% | 56,724 psi | 89% | 2976 fps | 100% |
| IMR 4451 Enduron | <<locked>> | 98% | 56,289 psi | 88% | 3081 fps | 96.6% |
| IMR 4831ᴾ | <<locked>> | 100% | 47,848 psi | 75% | 3012 fps | 97.9% |
| IMR 4895 | <<locked>> | 92% | 54,984 psi | 86% | 3123 fps | 99.6% |
| IMR 8208 XBR | <<locked>> | 88% | 54,882 psi | 86% | 3058 fps | 99.9% |
| Lovex D073.5 | <<locked>> | 84% | 55,100 psi | 86% | 3045 fps | 100% |
| Lovex D073.6 | <<locked>> | 90% | 55,419 psi | 87% | 3084 fps | 100% |
| Lovex S060 | <<locked>> | 90% | 55,666 psi | 87% | 3031 fps | 99.6% |
| Lovex S062 | <<locked>> | 94% | 55,912 psi | 88% | 3081 fps | 100% |
| Lovex S065ᴾ | <<locked>> | 100% | 54,868 psi | 86% | 3068 fps | 97.8% |
| Lovex S070ᴾ | <<locked>> | 100% | 52,286 psi | 82% | 3041 fps | 96.2% |
| Norma 201 | <<locked>> | 90% | 54,549 psi | 85% | 3051 fps | 99.9% |
| Norma 202 | <<locked>> | 90% | 55,056 psi | 86% | 3058 fps | 100% |
| Norma 203B | <<locked>> | 94% | 56,304 psi | 88% | 3133 fps | 99.7% |
| Norma URPᴾ | <<locked>> | 100% | 49,908 psi | 78% | 3068 fps | 98.2% |
| Ramshot Big Game | <<locked>> | 94% | 57,464 psi | 90% | 3166 fps | 99.7% |
| Ramshot Hunterᴾ | <<locked>> | 100% | 49,298 psi | 77% | 3058 fps | 96.3% |
| Ramshot TAC | <<locked>> | 88% | 55,622 psi | 87% | 3071 fps | 98.1% |
| Ramshot Wild Boar | <<locked>> | 88% | 54,839 psi | 86% | 3091 fps | 99.6% |
| Ramshot X-Terminator | <<locked>> | 86% | 56,159 psi | 88% | 3058 fps | 99.6% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 35,230 psi | 55% | 1936 fps | 100% |
| ReloadSwiss RS 40 | <<locked>> | 84% | 54,665 psi | 86% | 3045 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 94% | 55,361 psi | 87% | 3074 fps | 97.2% |
| ReloadSwiss RS 52 | <<locked>> | 90% | 53,722 psi | 84% | 3156 fps | 99.2% |
| ReloadSwiss RS 60 | <<locked>> | 98% | 57,290 psi | 90% | 3255 fps | 100% |
| ReloadSwiss RS 62ᴾ | <<locked>> | 100% | 50,009 psi | 78% | 3094 fps | 98% |
| ReloadSwiss RS 70ᴾ | <<locked>> | 100% | 50,807 psi | 80% | 3123 fps | 97.6% |
| Rottweil R 901 | <<locked>> | 88% | 55,259 psi | 87% | 3035 fps | 100% |
| Rottweil R 902 | <<locked>> | 92% | 54,607 psi | 86% | 3041 fps | 99.9% |
| Rottweil R 903 | <<locked>> | 98% | 56,608 psi | 89% | 3123 fps | 99.9% |
| Rottweil R 907ᴾ | <<locked>> | 100% | 57,725 psi | 90% | 3100 fps | 96.4% |
| Shooters World Long Rifleᴾ | <<locked>> | 100% | 54,868 psi | 86% | 3068 fps | 97.8% |
| Shooters World Match Rifle | <<locked>> | 90% | 55,419 psi | 87% | 3084 fps | 100% |
| Shooters World Precision | <<locked>> | 94% | 55,912 psi | 88% | 3081 fps | 100% |
| Shooters World SW4350ᴾ | <<locked>> | 100% | 52,286 psi | 82% | 3041 fps | 96.2% |
| Shooters World Tactical Rifle | <<locked>> | 82% | 54,157 psi | 85% | 3009 fps | 99.8% |
| SNPE Vectan SP 10 | <<locked>> | 82% | 57,624 psi | 90% | 3094 fps | 100% |
| SNPE Vectan SP 11 | <<locked>> | 96% | 55,230 psi | 87% | 3136 fps | 99.6% |
| SNPE Vectan SP 3 | <<locked>> | 84% | 57,406 psi | 90% | 3041 fps | 100% |
| SNPE Vectan SP 7 | <<locked>> | 88% | 53,679 psi | 84% | 3045 fps | 98.2% |
| SNPE Vectan SP 9 | <<locked>> | 90% | 54,201 psi | 85% | 3071 fps | 99.5% |
| SNPE Vectan Tubal 3000 | <<locked>> | 90% | 56,260 psi | 88% | 2992 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 96% | 56,521 psi | 89% | 2989 fps | 100% |
| SNPE Vectan Tubal 7000ᴾ | <<locked>> | 100% | 55,840 psi | 88% | 3018 fps | 96.6% |
| Somchem S321 | <<locked>> | 86% | 56,579 psi | 89% | 3100 fps | 100% |
| Somchem S335 | <<locked>> | 90% | 55,680 psi | 87% | 2992 fps | 100% |
| Somchem S341 | <<locked>> | 90% | 57,174 psi | 90% | 3097 fps | 99.7% |
| Somchem S355 | <<locked>> | 98% | 57,392 psi | 90% | 3127 fps | 99.9% |
| Somchem S365ᴾ | <<locked>> | 100% | 44,570 psi | 70% | 3012 fps | 99.6% |
| Vihtavuori N130 | <<locked>> | 86% | 56,304 psi | 88% | 2963 fps | 100% |
| Vihtavuori N133 | <<locked>> | 90% | 56,376 psi | 88% | 2976 fps | 100% |
| Vihtavuori N135 | <<locked>> | 94% | 57,653 psi | 90% | 3061 fps | 100% |
| Vihtavuori N140 | <<locked>> | 92% | 55,695 psi | 87% | 3035 fps | 100% |
| Vihtavuori N150 | <<locked>> | 98% | 55,216 psi | 87% | 3051 fps | 100% |
| Vihtavuori N160ᴾ | <<locked>> | 100% | 52,649 psi | 83% | 3071 fps | 98.5% |
| Vihtavuori N530 | <<locked>> | 88% | 55,796 psi | 87% | 3061 fps | 100% |
| Vihtavuori N540 | <<locked>> | 94% | 57,261 psi | 90% | 3074 fps | 100% |
| Vihtavuori N550ᴾ | <<locked>> | 100% | 51,750 psi | 81% | 3074 fps | 98.2% |
| Winchester 6.5 StaBALLᴾ | <<locked>> | 100% | 53,722 psi | 84% | 3054 fps | 99.8% |
| Winchester 748 | <<locked>> | 88% | 55,317 psi | 87% | 3110 fps | 100% |
| Winchester 760ᴾ | <<locked>> | 100% | 54,056 psi | 85% | 3136 fps | 96.5% |
| Winchester StaBALL Match | <<locked>> | 90% | 54,041 psi | 85% | 3081 fps | 99.8% |
Recommended = one of the top powders for this cartridge and bullet combination.
Start Load - Barrel Length: 24"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 2015 | <<locked>> | 80% | 43,888 psi | 69% | 2808 fps | 100% |
| Accurate 2460 | <<locked>> | 80% | 47,805 psi | 75% | 2917 fps | 100% |
| Accurate 2495 | <<locked>> | 80% | 36,085 psi | 57% | 2707 fps | 100% |
| Accurate 2520 | <<locked>> | 80% | 41,611 psi | 65% | 2848 fps | 99.6% |
| Accurate 4064 | <<locked>> | 80% | 34,156 psi | 54% | 2687 fps | 99.1% |
| Accurate 4350 | <<locked>> | 92% | 37,608 psi | 59% | 2822 fps | 95.1% |
| Accurate LT-30 | <<locked>> | 80% | 52,359 psi | 82% | 2900 fps | 100% |
| Accurate LT-32 | <<locked>> | 80% | 52,808 psi | 83% | 2927 fps | 100% |
| ADI AR 2206H | <<locked>> | 80% | 40,567 psi | 64% | 2818 fps | 97.3% |
| ADI AR 2208 | <<locked>> | 82% | 36,738 psi | 58% | 2710 fps | 95.3% |
| ADI AR 2219 | <<locked>> | 80% | 53,243 psi | 83% | 3022 fps | 100% |
| ADI Benchmark 8208 | <<locked>> | 80% | 42,670 psi | 67% | 2838 fps | 98.8% |
| Alliant AR-Comp | <<locked>> | 80% | 42,061 psi | 66% | 2838 fps | 100% |
| Alliant Power Pro 1200-R | <<locked>> | 80% | 49,705 psi | 78% | 3054 fps | 99.4% |
| Alliant Power Pro 2000-MR | 39 gr | 82% | 39,102 psi | 61% | 2887 fps | 95.7% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 33,634 psi | 53% | 2674 fps | 96.2% |
| Alliant Reloder-10x | <<locked>> | 80% | 49,530 psi | 78% | 2917 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 80% | 36,347 psi | 57% | 2740 fps | 95.4% |
| Alliant Reloder-16 | <<locked>> | 92% | 38,145 psi | 60% | 2838 fps | 95.2% |
| Alliant Reloder-17 | <<locked>> | 84% | 33,228 psi | 52% | 2736 fps | 95.1% |
| Baschieri & Pellagri 106 | <<locked>> | 80% | 51,837 psi | 81% | 2894 fps | 100% |
| Baschieri & Pellagri 107 | <<locked>> | 80% | 39,624 psi | 62% | 2812 fps | 95.9% |
| Bofors RP3 | <<locked>> | 80% | 32,721 psi | 51% | 2661 fps | 96% |
| Bofors RP7 | <<locked>> | 98% | 54,041 psi | 85% | 3041 fps | 95.6% |
| Hodgdon Benchmark | <<locked>> | 80% | 44,454 psi | 70% | 2831 fps | 99.4% |
| Hodgdon BL-C2 | <<locked>> | 80% | 40,959 psi | 64% | 2848 fps | 99% |
| Hodgdon CFE223 | <<locked>> | 80% | 45,237 psi | 71% | 2995 fps | 97.9% |
| Hodgdon H322 | <<locked>> | 80% | 48,689 psi | 76% | 2953 fps | 100% |
| Hodgdon H335 | <<locked>> | 80% | 49,603 psi | 78% | 2972 fps | 100% |
| Hodgdon H380 | <<locked>> | 86% | 41,800 psi | 66% | 2851 fps | 95.7% |
| Hodgdon H414 | <<locked>> | 98% | 50,198 psi | 79% | 3068 fps | 95.6% |
| Hodgdon H4895 | <<locked>> | 80% | 40,886 psi | 64% | 2835 fps | 97.9% |
| Hodgdon Hybrid 100V | <<locked>> | 90% | 32,706 psi | 51% | 2664 fps | 95.1% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 36,825 psi | 58% | 2789 fps | 97.3% |
| Hodgdon Superformance | <<locked>> | 98% | 51,663 psi | 81% | 3107 fps | 95.2% |
| Hodgdon TrailBoss | <<locked>> | 80% | 25,614 psi | 40% | 1683 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 39,160 psi | 61% | 2776 fps | 97.4% |
| IMR 3031 | <<locked>> | 80% | 40,132 psi | 63% | 2838 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 36,013 psi | 56% | 2690 fps | 95.4% |
| IMR 4166 Enduron | <<locked>> | 88% | 50,038 psi | 78% | 2943 fps | 95.4% |
| IMR 4198 | <<locked>> | 80% | 50,343 psi | 79% | 2884 fps | 100% |
| IMR 4451 Enduron | <<locked>> | 94% | 49,603 psi | 78% | 2966 fps | 95.1% |
| IMR 4831 | <<locked>> | 94% | 38,914 psi | 61% | 2831 fps | 95.6% |
| IMR 4895 | <<locked>> | 80% | 37,202 psi | 58% | 2772 fps | 96.4% |
| IMR 8208 XBR | <<locked>> | 80% | 42,670 psi | 67% | 2838 fps | 98.8% |
| Lovex D073.5 | <<locked>> | 80% | 47,964 psi | 75% | 2927 fps | 99.8% |
| Lovex D073.6 | <<locked>> | 80% | 38,856 psi | 61% | 2789 fps | 99.3% |
| Lovex S060 | <<locked>> | 80% | 40,988 psi | 64% | 2762 fps | 97.5% |
| Lovex S062 | <<locked>> | 80% | 35,723 psi | 56% | 2694 fps | 97.3% |
| Lovex S065 | <<locked>> | 92% | 42,670 psi | 67% | 2841 fps | 95% |
| Lovex S070 | <<locked>> | 98% | 48,965 psi | 77% | 2982 fps | 95.4% |
| Norma 201 | <<locked>> | 80% | 39,508 psi | 62% | 2769 fps | 98.3% |
| Norma 202 | <<locked>> | 80% | 39,842 psi | 62% | 2789 fps | 99.7% |
| Norma 203B | <<locked>> | 80% | 35,708 psi | 56% | 2726 fps | 95.9% |
| Norma URP | <<locked>> | 92% | 38,319 psi | 60% | 2831 fps | 95.1% |
| Ramshot Big Game | <<locked>> | 80% | 35,143 psi | 55% | 2733 fps | 95.4% |
| Ramshot Hunter | <<locked>> | 98% | 45,832 psi | 72% | 2989 fps | 95.4% |
| Ramshot TAC | <<locked>> | 80% | 42,641 psi | 67% | 2831 fps | 95.2% |
| Ramshot Wild Boar | <<locked>> | 80% | 41,727 psi | 65% | 2848 fps | 97.6% |
| Ramshot X-Terminator | <<locked>> | 80% | 46,209 psi | 72% | 2887 fps | 98.4% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 26,005 psi | 41% | 1729 fps | 100% |
| ReloadSwiss RS 40 | <<locked>> | 80% | 48,008 psi | 75% | 2933 fps | 99.9% |
| ReloadSwiss RS 50 | <<locked>> | 90% | 48,312 psi | 76% | 2949 fps | 95.7% |
| ReloadSwiss RS 52 | 36.9 gr | 80% | 37,579 psi | 59% | 2835 fps | 95.8% |
| ReloadSwiss RS 60 | 37.5 gr | 80% | 30,893 psi | 48% | 2680 fps | 96.8% |
| ReloadSwiss RS 62 | <<locked>> | 94% | 40,408 psi | 63% | 2904 fps | 95.6% |
| ReloadSwiss RS 70 | <<locked>> | 96% | 44,193 psi | 69% | 2986 fps | 95.9% |
| Rottweil R 901 | <<locked>> | 80% | 43,236 psi | 68% | 2828 fps | 99.9% |
| Rottweil R 902 | <<locked>> | 80% | 37,565 psi | 59% | 2720 fps | 97.8% |
| Rottweil R 903 | <<locked>> | 82% | 33,127 psi | 52% | 2664 fps | 95.8% |
| Rottweil R 907 | <<locked>> | 98% | 54,041 psi | 85% | 3041 fps | 95.6% |
| Shooters World Long Rifle | <<locked>> | 92% | 42,670 psi | 67% | 2841 fps | 95% |
| Shooters World Match Rifle | <<locked>> | 80% | 38,856 psi | 61% | 2789 fps | 99.3% |
| Shooters World Precision | <<locked>> | 80% | 35,723 psi | 56% | 2694 fps | 97.3% |
| Shooters World SW4350 | <<locked>> | 98% | 48,965 psi | 77% | 2982 fps | 95.4% |
| Shooters World Tactical Rifle | <<locked>> | 80% | 50,676 psi | 79% | 2949 fps | 99.6% |
| SNPE Vectan SP 10 | <<locked>> | 80% | 53,664 psi | 84% | 3035 fps | 100% |
| SNPE Vectan SP 11 | <<locked>> | 82% | 34,272 psi | 54% | 2717 fps | 95.1% |
| SNPE Vectan SP 3 | <<locked>> | 80% | 50,517 psi | 79% | 2940 fps | 100% |
| SNPE Vectan SP 7 | <<locked>> | 80% | 40,582 psi | 64% | 2795 fps | 95.2% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 38,957 psi | 61% | 2779 fps | 96.8% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 41,075 psi | 64% | 2736 fps | 99.8% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 33,852 psi | 53% | 2585 fps | 99.4% |
| SNPE Vectan Tubal 7000 | <<locked>> | 96% | 48,718 psi | 76% | 2904 fps | 95.1% |
| Somchem S321 | <<locked>> | 80% | 45,948 psi | 72% | 2920 fps | 99.5% |
| Somchem S335 | <<locked>> | 80% | 40,669 psi | 64% | 2740 fps | 100% |
| Somchem S341 | <<locked>> | 80% | 40,335 psi | 63% | 2799 fps | 97.2% |
| Somchem S355 | <<locked>> | 80% | 31,981 psi | 50% | 2618 fps | 95% |
| Somchem S365 | <<locked>> | 88% | 29,762 psi | 47% | 2644 fps | 95.4% |
| Vihtavuori N130 | <<locked>> | 80% | 46,615 psi | 73% | 2815 fps | 100% |
| Vihtavuori N133 | <<locked>> | 80% | 41,336 psi | 65% | 2740 fps | 100% |
| Vihtavuori N135 | <<locked>> | 80% | 36,622 psi | 57% | 2710 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 37,681 psi | 59% | 2717 fps | 99.6% |
| Vihtavuori N150 | <<locked>> | 80% | 30,371 psi | 48% | 2556 fps | 96% |
| Vihtavuori N160 | <<locked>> | 92% | 40,147 psi | 63% | 2831 fps | 95.6% |
| Vihtavuori N530 | <<locked>> | 80% | 42,351 psi | 66% | 2825 fps | 98.8% |
| Vihtavuori N540 | <<locked>> | 80% | 36,056 psi | 56% | 2697 fps | 99.1% |
| Vihtavuori N550 | <<locked>> | 92% | 39,421 psi | 62% | 2831 fps | 95.2% |
| Winchester 6.5 StaBALL | <<locked>> | 86% | 33,388 psi | 52% | 2638 fps | 95.5% |
| Winchester 748 | <<locked>> | 80% | 41,727 psi | 65% | 2871 fps | 99.3% |
| Winchester 760 | <<locked>> | 98% | 50,575 psi | 79% | 3074 fps | 95.7% |
| Winchester StaBALL Match | <<locked>> | 80% | 38,290 psi | 60% | 2779 fps | 97.3% |
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 102 powders for .25 WSSM loaded with the .257 | 100gr | Osprey Virtus. Alliant Reloder-17 delivers the highest muzzle velocity at 3,255 fps; across all powders the maximum-charge window runs from 1,890 fps to 3,255 fps. Accurate 4350 gives the best case fill at 100 %, and 102 of the 102 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (440 MPa), the top charges use 55–90 %, leaving at least 10 % headroom. The 100.0 gr projectile in 0.257" calls for a 1:10.0 twist; slower twists will usually not stabilise this weight. Accurate 4350, Alliant Reloder-16, Alliant Reloder-17 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 Power Pro 2000-MR, ReloadSwiss RS 60, ReloadSwiss RS 52 rank at the top here: for .25 WSSM with the .257 | 100gr | Osprey Virtus they combine a high case fill with complete burn and sit in the upper velocity band. Always begin at the start load and work up in small increments while checking case and primer for pressure signs.