Load Specifications
Bullet:.257 | 100gr | Speer Hot-Cor
Bullet Manufacturer:Speer
Bullet Weight:100 gr
Bullet Diameter:0.257"
Bullet Length:<<locked>>
Caliber:.255 GS load data
Case Length (l3):2.165"
Cartridge Length (C.O.L.):<<locked>>
Case Capacity:62 Grains of Water
Primer Size:Large Rifle (LR)
Barrel Length:24"
Max. allowed Pressure:63,817 psi
Recommended Twist Rate:1:12.5
Load data in caliber .255 GS with .257 | 100gr | Speer Hot-Cor bullet and 99 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Alliant Reloder-17, ReloadSwiss RS 60 and Winchester 760.
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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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>> | 82% | 56,608 psi | 89% | 3054 fps | 100% |
| Accurate 2495 | <<locked>> | 86% | 56,463 psi | 88% | 3084 fps | 100% |
| Accurate 2520 | <<locked>> | 82% | 57,653 psi | 90% | 3150 fps | 100% |
| Accurate 2700 | <<locked>> | 86% | 54,810 psi | 86% | 3081 fps | 97.1% |
| Accurate 3100ᴾ | <<locked>> | 100% | 47,239 psi | 74% | 3028 fps | 97.3% |
| Accurate 4064 | <<locked>> | 88% | 56,449 psi | 88% | 3133 fps | 100% |
| Accurate 4350 | <<locked>> | 96% | 57,058 psi | 89% | 3232 fps | 99.8% |
| ADI AR 2206H | <<locked>> | 84% | 56,014 psi | 88% | 3166 fps | 100% |
| ADI AR 2208 | <<locked>> | 90% | 57,159 psi | 90% | 3169 fps | 99.9% |
| ADI AR 2209ᴾ | <<locked>> | 100% | 54,882 psi | 86% | 3205 fps | 96.2% |
| ADI Benchmark 8208 | <<locked>> | 82% | 54,650 psi | 86% | 3107 fps | 100% |
| Alliant AR-Comp | <<locked>> | 82% | 56,188 psi | 88% | 3087 fps | 100% |
| Alliant Power Pro 2000-MR | <<locked>> | 86% | 56,362 psi | 88% | 3297 fps | 99.9% |
| Alliant Reloder- TS 15.5 | <<locked>> | 90% | 57,580 psi | 90% | 3192 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 86% | 54,592 psi | 86% | 3159 fps | 99.8% |
| Alliant Reloder-16 | <<locked>> | 98% | 57,667 psi | 90% | 3291 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 92% | 55,564 psi | 87% | 3271 fps | 100% |
| Alliant Reloder-19ᴾ | <<locked>> | 100% | 53,635 psi | 84% | 3182 fps | 96.1% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 44,643 psi | 70% | 3061 fps | 99.6% |
| Alliant Reloder-26ᴾ | <<locked>> | 100% | 50,676 psi | 79% | 3255 fps | 99.3% |
| Baschieri & Pellagri 107 | <<locked>> | 84% | 55,970 psi | 88% | 3179 fps | 99.7% |
| Bofors RP3 | <<locked>> | 88% | 54,708 psi | 86% | 3150 fps | 100% |
| Bofors RP7 | <<locked>> | 92% | 54,737 psi | 86% | 3123 fps | 97.3% |
| Hodgdon Benchmark | <<locked>> | 82% | 56,318 psi | 88% | 3094 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 82% | 54,621 psi | 86% | 3140 fps | 100% |
| Hodgdon H380 | <<locked>> | 88% | 55,724 psi | 87% | 3169 fps | 99.4% |
| Hodgdon H414 | <<locked>> | 94% | 55,637 psi | 87% | 3222 fps | 98.1% |
| Hodgdon H4350 | <<locked>> | 92% | 55,912 psi | 88% | 3182 fps | 96.8% |
| Hodgdon H4895 | <<locked>> | 84% | 56,623 psi | 89% | 3176 fps | 100% |
| Hodgdon Hybrid 100V | <<locked>> | 98% | 54,331 psi | 85% | 3156 fps | 100% |
| Hodgdon LEVERevolution | <<locked>> | 86% | 56,608 psi | 89% | 3212 fps | 100% |
| Hodgdon Superformance | <<locked>> | 94% | 56,376 psi | 88% | 3261 fps | 97.9% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 35,853 psi | 56% | 1982 fps | 100% |
| Hodgdon VARGET | <<locked>> | 84% | 54,056 psi | 85% | 3117 fps | 100% |
| IMR 3031 | <<locked>> | 84% | 57,000 psi | 89% | 3159 fps | 100% |
| IMR 4064 | <<locked>> | 88% | 56,420 psi | 88% | 3146 fps | 99.9% |
| IMR 4166 Enduron | <<locked>> | 86% | 56,144 psi | 88% | 3123 fps | 98% |
| IMR 4350 | <<locked>> | 96% | 55,158 psi | 86% | 3150 fps | 97.4% |
| IMR 4451 Enduron | <<locked>> | 92% | 56,463 psi | 88% | 3156 fps | 98% |
| IMR 4831 | <<locked>> | 98% | 57,276 psi | 90% | 3215 fps | 99.8% |
| IMR 4895 | <<locked>> | 86% | 56,028 psi | 88% | 3196 fps | 100% |
| IMR 8208 XBR | <<locked>> | 82% | 54,650 psi | 86% | 3107 fps | 100% |
| Lovex D073.6 | <<locked>> | 84% | 56,362 psi | 88% | 3140 fps | 100% |
| Lovex S060 | <<locked>> | 84% | 55,172 psi | 86% | 3087 fps | 100% |
| Lovex S062 | <<locked>> | 88% | 56,782 psi | 89% | 3146 fps | 100% |
| Lovex S065 | <<locked>> | 94% | 56,014 psi | 88% | 3146 fps | 99% |
| Lovex S070 | <<locked>> | 96% | 57,159 psi | 90% | 3186 fps | 98.4% |
| Norma 201 | <<locked>> | 84% | 54,679 psi | 86% | 3104 fps | 100% |
| Norma 202 | <<locked>> | 84% | 55,477 psi | 87% | 3107 fps | 100% |
| Norma 203B | <<locked>> | 88% | 57,188 psi | 90% | 3199 fps | 100% |
| Norma 204 | <<locked>> | 96% | 56,173 psi | 88% | 3202 fps | 96.3% |
| Norma MRPᴾ | <<locked>> | 100% | 50,270 psi | 79% | 3205 fps | 97% |
| Norma URP | <<locked>> | 96% | 55,535 psi | 87% | 3212 fps | 99.6% |
| Ramshot Big Game | <<locked>> | 86% | 54,534 psi | 85% | 3169 fps | 99.9% |
| Ramshot Hunter | <<locked>> | 96% | 54,650 psi | 86% | 3209 fps | 98.6% |
| Ramshot TAC | <<locked>> | 82% | 55,114 psi | 86% | 3127 fps | 99% |
| Ramshot Wild Boar | <<locked>> | 82% | 54,781 psi | 86% | 3146 fps | 99.9% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 36,550 psi | 57% | 2031 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 88% | 55,579 psi | 87% | 3143 fps | 98.4% |
| ReloadSwiss RS 52 | <<locked>> | 84% | 55,303 psi | 87% | 3232 fps | 99.8% |
| ReloadSwiss RS 60 | <<locked>> | 90% | 54,868 psi | 86% | 3264 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 96% | 57,043 psi | 89% | 3255 fps | 99.7% |
| ReloadSwiss RS 70 | <<locked>> | 96% | 55,622 psi | 87% | 3281 fps | 99.5% |
| Rottweil R 901 | <<locked>> | 82% | 55,419 psi | 87% | 3087 fps | 100% |
| Rottweil R 902 | <<locked>> | 86% | 55,274 psi | 87% | 3107 fps | 100% |
| Rottweil R 903 | <<locked>> | 90% | 54,897 psi | 86% | 3146 fps | 100% |
| Rottweil R 905ᴾ | <<locked>> | 100% | 52,634 psi | 82% | 3169 fps | 96% |
| Rottweil R 907 | <<locked>> | 92% | 54,737 psi | 86% | 3123 fps | 97.3% |
| Shooters World Long Rifle | <<locked>> | 94% | 56,014 psi | 88% | 3146 fps | 99% |
| Shooters World Match Rifle | <<locked>> | 84% | 56,362 psi | 88% | 3140 fps | 100% |
| Shooters World Precision | <<locked>> | 88% | 56,782 psi | 89% | 3146 fps | 100% |
| Shooters World SW4350 | <<locked>> | 96% | 57,159 psi | 90% | 3186 fps | 98.4% |
| SNPE Vectan SP 11 | <<locked>> | 90% | 56,652 psi | 89% | 3212 fps | 100% |
| SNPE Vectan SP 3 | <<locked>> | 84% | 56,347 psi | 88% | 3025 fps | 100% |
| SNPE Vectan SP 7 | <<locked>> | 84% | 57,595 psi | 90% | 3169 fps | 99.5% |
| SNPE Vectan SP 9 | <<locked>> | 84% | 54,636 psi | 86% | 3133 fps | 99.9% |
| SNPE Vectan Tubal 3000 | <<locked>> | 84% | 55,970 psi | 88% | 3041 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 90% | 56,550 psi | 89% | 3041 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 94% | 56,144 psi | 88% | 3094 fps | 98% |
| SNPE Vectan Tubal 8000ᴾ | <<locked>> | 100% | 52,141 psi | 82% | 3159 fps | 95.9% |
| Somchem S335 | <<locked>> | 84% | 55,376 psi | 87% | 3035 fps | 100% |
| Somchem S341 | <<locked>> | 84% | 57,029 psi | 89% | 3153 fps | 100% |
| Somchem S355 | <<locked>> | 90% | 55,114 psi | 86% | 3143 fps | 100% |
| Somchem S365 | <<locked>> | 98% | 54,375 psi | 85% | 3219 fps | 100% |
| Somchem S385ᴾ | <<locked>> | 100% | 53,476 psi | 84% | 3146 fps | 97.1% |
| Vihtavuori N133 | <<locked>> | 84% | 56,347 psi | 88% | 3025 fps | 100% |
| Vihtavuori N135 | <<locked>> | 86% | 55,434 psi | 87% | 3071 fps | 100% |
| Vihtavuori N140 | <<locked>> | 86% | 56,057 psi | 88% | 3084 fps | 100% |
| Vihtavuori N150 | <<locked>> | 92% | 56,304 psi | 88% | 3117 fps | 100% |
| Vihtavuori N160 | <<locked>> | 94% | 54,317 psi | 85% | 3150 fps | 99.5% |
| Vihtavuori N530 | <<locked>> | 82% | 55,201 psi | 87% | 3110 fps | 100% |
| Vihtavuori N540 | <<locked>> | 86% | 54,302 psi | 85% | 3077 fps | 100% |
| Vihtavuori N550 | <<locked>> | 96% | 57,159 psi | 90% | 3215 fps | 99.6% |
| Vihtavuori N555ᴾ | <<locked>> | 100% | 49,719 psi | 78% | 3146 fps | 99.5% |
| Winchester 6.5 StaBALL | <<locked>> | 94% | 54,621 psi | 86% | 3127 fps | 100% |
| Winchester 748 | <<locked>> | 82% | 55,724 psi | 87% | 3163 fps | 100% |
| Winchester 760 | <<locked>> | 94% | 55,941 psi | 88% | 3225 fps | 98.1% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 40,205 psi | 63% | 3084 fps | 99.8% |
| Winchester StaBALL Match | <<locked>> | 84% | 54,404 psi | 85% | 3136 fps | 100% |
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% | 53,243 psi | 83% | 3002 fps | 100% |
| Accurate 2495 | <<locked>> | 80% | 46,180 psi | 72% | 2923 fps | 100% |
| Accurate 2520 | <<locked>> | 80% | 53,925 psi | 85% | 3094 fps | 100% |
| Accurate 2700 | <<locked>> | 82% | 47,819 psi | 75% | 2953 fps | 95.5% |
| Accurate 3100 | <<locked>> | 96% | 41,234 psi | 65% | 2907 fps | 95.7% |
| Accurate 4064 | <<locked>> | 80% | 43,671 psi | 68% | 2920 fps | 100% |
| Accurate 4350 | <<locked>> | 82% | 34,925 psi | 55% | 2785 fps | 95.3% |
| ADI AR 2206H | <<locked>> | 80% | 49,443 psi | 77% | 3048 fps | 99.6% |
| ADI AR 2208 | <<locked>> | 80% | 41,887 psi | 66% | 2881 fps | 98.1% |
| ADI AR 2209 | <<locked>> | 98% | 51,271 psi | 80% | 3136 fps | 95.3% |
| ADI Benchmark 8208 | <<locked>> | 80% | 51,517 psi | 81% | 3054 fps | 100% |
| Alliant AR-Comp | <<locked>> | 80% | 52,692 psi | 83% | 3035 fps | 100% |
| Alliant Power Pro 2000-MR | <<locked>> | 80% | 45,353 psi | 71% | 3087 fps | 98.8% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 42,061 psi | 66% | 2910 fps | 99.2% |
| Alliant Reloder-15 | <<locked>> | 80% | 45,020 psi | 71% | 2979 fps | 98.8% |
| Alliant Reloder-16 | <<locked>> | 82% | 34,693 psi | 54% | 2799 fps | 95.4% |
| Alliant Reloder-17 | 44.8 gr | 80% | 36,434 psi | 57% | 2874 fps | 97.8% |
| Alliant Reloder-19 | <<locked>> | 98% | 50,459 psi | 79% | 3127 fps | 95.3% |
| Alliant Reloder-23 | <<locked>> | 88% | 30,414 psi | 48% | 2694 fps | 95.2% |
| Alliant Reloder-26 | <<locked>> | 92% | 38,043 psi | 60% | 2969 fps | 96% |
| Baschieri & Pellagri 107 | <<locked>> | 80% | 48,863 psi | 77% | 3054 fps | 99% |
| Bofors RP3 | <<locked>> | 80% | 41,901 psi | 66% | 2913 fps | 99.3% |
| Bofors RP7 | <<locked>> | 86% | 45,179 psi | 71% | 2940 fps | 95% |
| Hodgdon Benchmark | <<locked>> | 80% | 52,808 psi | 83% | 3038 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 80% | 50,807 psi | 80% | 3077 fps | 100% |
| Hodgdon H380 | <<locked>> | 80% | 42,583 psi | 67% | 2920 fps | 97.3% |
| Hodgdon H414 | <<locked>> | 86% | 42,728 psi | 67% | 2969 fps | 95% |
| Hodgdon H4350 | <<locked>> | 88% | 49,023 psi | 77% | 3054 fps | 95.2% |
| Hodgdon H4895 | <<locked>> | 80% | 49,937 psi | 78% | 3061 fps | 99.8% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 30,066 psi | 47% | 2631 fps | 95.3% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 46,311 psi | 73% | 3035 fps | 99.8% |
| Hodgdon Superformance | <<locked>> | 88% | 45,150 psi | 71% | 3045 fps | 95.2% |
| Hodgdon TrailBoss | <<locked>> | 80% | 26,716 psi | 42% | 1772 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 47,659 psi | 75% | 3005 fps | 99.7% |
| IMR 3031 | <<locked>> | 80% | 49,908 psi | 78% | 3051 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 43,990 psi | 69% | 2920 fps | 98.7% |
| IMR 4166 Enduron | <<locked>> | 80% | 46,470 psi | 73% | 2943 fps | 96% |
| IMR 4350 | <<locked>> | 90% | 45,629 psi | 72% | 2969 fps | 95.2% |
| IMR 4451 Enduron | <<locked>> | 84% | 44,121 psi | 69% | 2920 fps | 95.2% |
| IMR 4831 | <<locked>> | 82% | 33,736 psi | 53% | 2736 fps | 95% |
| IMR 4895 | <<locked>> | 80% | 46,151 psi | 72% | 3015 fps | 99.3% |
| IMR 8208 XBR | <<locked>> | 80% | 51,517 psi | 81% | 3054 fps | 100% |
| Lovex D073.6 | <<locked>> | 80% | 49,269 psi | 77% | 3028 fps | 100% |
| Lovex S060 | <<locked>> | 80% | 48,762 psi | 76% | 2976 fps | 99.6% |
| Lovex S062 | <<locked>> | 80% | 44,106 psi | 69% | 2923 fps | 99.7% |
| Lovex S065 | <<locked>> | 82% | 38,740 psi | 61% | 2802 fps | 95.2% |
| Lovex S070 | <<locked>> | 88% | 44,527 psi | 70% | 2949 fps | 95.7% |
| Norma 201 | <<locked>> | 80% | 48,182 psi | 76% | 2992 fps | 99.9% |
| Norma 202 | <<locked>> | 80% | 48,849 psi | 77% | 3002 fps | 100% |
| Norma 203B | <<locked>> | 80% | 44,411 psi | 70% | 2966 fps | 99.1% |
| Norma 204 | <<locked>> | 94% | 52,460 psi | 82% | 3140 fps | 95.5% |
| Norma MRP | <<locked>> | 96% | 43,584 psi | 68% | 3061 fps | 95% |
| Norma URP | <<locked>> | 82% | 34,954 psi | 55% | 2785 fps | 95.2% |
| Ramshot Big Game | <<locked>> | 80% | 44,150 psi | 69% | 2979 fps | 98.9% |
| Ramshot Hunter | <<locked>> | 88% | 41,814 psi | 66% | 2956 fps | 95.7% |
| Ramshot TAC | <<locked>> | 80% | 51,474 psi | 81% | 3064 fps | 98.5% |
| Ramshot Wild Boar | <<locked>> | 80% | 51,358 psi | 80% | 3087 fps | 99.8% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 27,166 psi | 43% | 1818 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 42,844 psi | 67% | 2900 fps | 95.7% |
| ReloadSwiss RS 52 | <<locked>> | 80% | 47,848 psi | 75% | 3097 fps | 99.2% |
| ReloadSwiss RS 60 | 44.8 gr | 80% | 38,725 psi | 61% | 2946 fps | 99.9% |
| ReloadSwiss RS 62 | <<locked>> | 84% | 37,188 psi | 58% | 2864 fps | 95.8% |
| ReloadSwiss RS 70 | <<locked>> | 86% | 39,523 psi | 62% | 2940 fps | 96% |
| Rottweil R 901 | <<locked>> | 80% | 52,243 psi | 82% | 3035 fps | 100% |
| Rottweil R 902 | <<locked>> | 80% | 45,861 psi | 72% | 2940 fps | 99.8% |
| Rottweil R 903 | <<locked>> | 80% | 39,465 psi | 62% | 2851 fps | 98.7% |
| Rottweil R 905 | <<locked>> | 98% | 49,327 psi | 77% | 3104 fps | 95.2% |
| Rottweil R 907 | <<locked>> | 86% | 45,179 psi | 71% | 2940 fps | 95% |
| Shooters World Long Rifle | <<locked>> | 82% | 38,740 psi | 61% | 2802 fps | 95.2% |
| Shooters World Match Rifle | <<locked>> | 80% | 49,269 psi | 77% | 3028 fps | 100% |
| Shooters World Precision | <<locked>> | 80% | 44,106 psi | 69% | 2923 fps | 99.7% |
| Shooters World SW4350 | <<locked>> | 88% | 44,527 psi | 70% | 2949 fps | 95.7% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 40,335 psi | 63% | 2900 fps | 98.2% |
| SNPE Vectan SP 3 | <<locked>> | 80% | 49,617 psi | 78% | 2927 fps | 100% |
| SNPE Vectan SP 7 | <<locked>> | 80% | 50,183 psi | 79% | 3041 fps | 98.7% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 47,674 psi | 75% | 3009 fps | 99.5% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 49,182 psi | 77% | 2936 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 41,263 psi | 65% | 2785 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 86% | 43,395 psi | 68% | 2861 fps | 95.2% |
| SNPE Vectan Tubal 8000 | <<locked>> | 98% | 48,863 psi | 77% | 3100 fps | 95% |
| Somchem S335 | <<locked>> | 80% | 48,950 psi | 77% | 2933 fps | 100% |
| Somchem S341 | <<locked>> | 80% | 49,763 psi | 78% | 3031 fps | 99.6% |
| Somchem S355 | <<locked>> | 80% | 39,972 psi | 63% | 2854 fps | 98.6% |
| Somchem S365 | <<locked>> | 80% | 29,370 psi | 46% | 2667 fps | 96.6% |
| Somchem S385 | <<locked>> | 96% | 46,992 psi | 74% | 3025 fps | 95.5% |
| Vihtavuori N133 | <<locked>> | 80% | 49,617 psi | 78% | 2927 fps | 100% |
| Vihtavuori N135 | <<locked>> | 80% | 45,687 psi | 72% | 2917 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 46,238 psi | 72% | 2927 fps | 100% |
| Vihtavuori N150 | <<locked>> | 80% | 38,174 psi | 60% | 2782 fps | 99.2% |
| Vihtavuori N160 | <<locked>> | 82% | 36,463 psi | 57% | 2789 fps | 95.7% |
| Vihtavuori N530 | <<locked>> | 80% | 51,605 psi | 81% | 3051 fps | 100% |
| Vihtavuori N540 | <<locked>> | 80% | 44,657 psi | 70% | 2913 fps | 100% |
| Vihtavuori N550 | <<locked>> | 82% | 36,129 psi | 57% | 2789 fps | 95.4% |
| Vihtavuori N555 | <<locked>> | 88% | 33,185 psi | 52% | 2782 fps | 95.4% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 33,750 psi | 53% | 2700 fps | 97.2% |
| Winchester 748 | <<locked>> | 80% | 52,112 psi | 82% | 3104 fps | 100% |
| Winchester 760 | 47.2 gr | 86% | 42,728 psi | 67% | 2969 fps | 95% |
| Winchester StaBALL HD | <<locked>> | 92% | 30,806 psi | 48% | 2792 fps | 96.2% |
| Winchester StaBALL Match | <<locked>> | 80% | 47,659 psi | 75% | 3022 fps | 99.7% |
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 99 powders for .255 GS loaded with the .257 | 100gr | Speer Hot-Cor. Alliant Power Pro 2000-MR delivers the highest muzzle velocity at 3,297 fps; across all powders the maximum-charge window runs from 1,982 fps to 3,297 fps. Accurate 3100 gives the best case fill at 100 %, and 99 of the 99 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (440 MPa), the top charges use 56–90 %, leaving at least 10 % headroom. The 100.0 gr projectile in 0.257" calls for a 1:12.5 twist; slower twists will usually not stabilise this weight. Accurate 3100, ADI AR 2209, Alliant Reloder-19 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-17, ReloadSwiss RS 60, Winchester 760 rank at the top here: for .255 GS with the .257 | 100gr | Speer Hot-Cor 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.