Load Specifications
Bullet:.257 | 90gr | Hornady GMX
Bullet Manufacturer:Hornady
Bullet Weight:90 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:1:10.5
Load data in caliber .255 GS with .257 | 90gr | Hornady GMX 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 Power Pro 2000-MR, ReloadSwiss RS 60 and Alliant Reloder-17.
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>> | 84% | 54,389 psi | 85% | 3176 fps | 100% |
| Accurate 2460 | <<locked>> | 82% | 56,333 psi | 88% | 3251 fps | 100% |
| Accurate 2495 | <<locked>> | 90% | 56,304 psi | 88% | 3241 fps | 100% |
| Accurate 2520 | <<locked>> | 84% | 54,940 psi | 86% | 3261 fps | 100% |
| Accurate 2700 | <<locked>> | 90% | 56,217 psi | 88% | 3235 fps | 96% |
| Accurate 4064 | <<locked>> | 92% | 56,579 psi | 89% | 3294 fps | 100% |
| Accurate 4350ᴾ | <<locked>> | 100% | 57,072 psi | 89% | 3376 fps | 99.2% |
| ADI AR 2206H | <<locked>> | 88% | 57,246 psi | 90% | 3333 fps | 99.8% |
| ADI AR 2208 | <<locked>> | 92% | 54,955 psi | 86% | 3271 fps | 99.3% |
| ADI Benchmark 8208 | <<locked>> | 86% | 56,028 psi | 88% | 3278 fps | 100% |
| Alliant AR-Comp | <<locked>> | 86% | 57,130 psi | 90% | 3261 fps | 100% |
| Alliant Power Pro 2000-MR | <<locked>> | 90% | 57,348 psi | 90% | 3465 fps | 99.6% |
| Alliant Reloder- TS 15.5 | <<locked>> | 92% | 54,766 psi | 86% | 3294 fps | 99.9% |
| Alliant Reloder-10x | <<locked>> | 82% | 57,217 psi | 90% | 3235 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 90% | 55,564 psi | 87% | 3323 fps | 99.5% |
| Alliant Reloder-16ᴾ | <<locked>> | 100% | 54,795 psi | 86% | 3386 fps | 99.3% |
| Alliant Reloder-17 | <<locked>> | 96% | 56,217 psi | 88% | 3428 fps | 100% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 38,870 psi | 61% | 3058 fps | 97.4% |
| Alliant Reloder-26ᴾ | <<locked>> | 100% | 43,801 psi | 69% | 3232 fps | 96.6% |
| Baschieri & Pellagri 107 | <<locked>> | 88% | 57,435 psi | 90% | 3346 fps | 99.4% |
| Bofors RP3 | <<locked>> | 92% | 55,332 psi | 87% | 3307 fps | 99.9% |
| Bofors RP7 | <<locked>> | 96% | 55,724 psi | 87% | 3271 fps | 96.2% |
| Hodgdon Benchmark | <<locked>> | 84% | 54,375 psi | 85% | 3209 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 86% | 55,796 psi | 87% | 3310 fps | 100% |
| Hodgdon CFE223 | <<locked>> | 82% | 53,867 psi | 84% | 3353 fps | 99.3% |
| Hodgdon H322 | <<locked>> | 82% | 56,811 psi | 89% | 3281 fps | 100% |
| Hodgdon H380 | <<locked>> | 92% | 56,710 psi | 89% | 3323 fps | 98.8% |
| Hodgdon H414 | <<locked>> | 98% | 56,376 psi | 88% | 3373 fps | 97.1% |
| Hodgdon H4895 | <<locked>> | 86% | 54,070 psi | 85% | 3281 fps | 99.8% |
| Hodgdon Hybrid 100Vᴾ | <<locked>> | 100% | 50,778 psi | 80% | 3238 fps | 99.6% |
| Hodgdon LEVERevolution | <<locked>> | 88% | 53,969 psi | 85% | 3320 fps | 99.9% |
| Hodgdon Superformance | <<locked>> | 96% | 53,534 psi | 84% | 3340 fps | 96% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 35,244 psi | 55% | 2070 fps | 100% |
| Hodgdon VARGET | <<locked>> | 88% | 55,492 psi | 87% | 3287 fps | 99.8% |
| IMR 3031 | <<locked>> | 88% | 57,653 psi | 90% | 3330 fps | 100% |
| IMR 4064 | <<locked>> | 90% | 54,418 psi | 85% | 3258 fps | 99.4% |
| IMR 4166 Enduron | <<locked>> | 88% | 54,505 psi | 85% | 3228 fps | 96.6% |
| IMR 4198 | <<locked>> | 82% | 57,290 psi | 90% | 3196 fps | 100% |
| IMR 4350ᴾ | <<locked>> | 100% | 56,028 psi | 88% | 3294 fps | 96.3% |
| IMR 4451 Enduron | <<locked>> | 96% | 57,682 psi | 90% | 3310 fps | 97.1% |
| IMR 4831ᴾ | <<locked>> | 100% | 53,940 psi | 85% | 3304 fps | 98.9% |
| IMR 4895 | <<locked>> | 90% | 57,014 psi | 89% | 3360 fps | 99.8% |
| IMR 8208 XBR | <<locked>> | 86% | 56,028 psi | 88% | 3278 fps | 100% |
| Lovex D073.5 | <<locked>> | 82% | 56,376 psi | 88% | 3261 fps | 100% |
| Lovex D073.6 | <<locked>> | 88% | 57,101 psi | 89% | 3304 fps | 100% |
| Lovex S060 | <<locked>> | 88% | 56,594 psi | 89% | 3251 fps | 99.7% |
| Lovex S062 | <<locked>> | 92% | 57,508 psi | 90% | 3307 fps | 100% |
| Lovex S065 | <<locked>> | 98% | 56,739 psi | 89% | 3297 fps | 98.2% |
| Lovex S070 | <<locked>> | 98% | 54,346 psi | 85% | 3271 fps | 96.8% |
| Norma 201 | <<locked>> | 88% | 55,738 psi | 87% | 3271 fps | 100% |
| Norma 202 | <<locked>> | 88% | 56,275 psi | 88% | 3274 fps | 100% |
| Norma 203B | <<locked>> | 90% | 54,752 psi | 86% | 3307 fps | 99.6% |
| Norma URPᴾ | <<locked>> | 100% | 56,217 psi | 88% | 3366 fps | 99.1% |
| Ramshot Big Game | <<locked>> | 90% | 55,303 psi | 87% | 3327 fps | 99.6% |
| Ramshot Hunterᴾ | <<locked>> | 100% | 54,926 psi | 86% | 3350 fps | 97.7% |
| Ramshot TAC | <<locked>> | 86% | 56,826 psi | 89% | 3294 fps | 98.4% |
| Ramshot Wild Boar | <<locked>> | 86% | 56,579 psi | 89% | 3317 fps | 99.7% |
| Ramshot X-Terminator | <<locked>> | 84% | 57,377 psi | 90% | 3281 fps | 99.7% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 35,505 psi | 56% | 2116 fps | 100% |
| ReloadSwiss RS 40 | <<locked>> | 82% | 55,637 psi | 87% | 3264 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 92% | 57,130 psi | 90% | 3304 fps | 97.7% |
| ReloadSwiss RS 52 | <<locked>> | 88% | 55,970 psi | 88% | 3392 fps | 99.5% |
| ReloadSwiss RS 60 | <<locked>> | 94% | 55,883 psi | 88% | 3432 fps | 100% |
| ReloadSwiss RS 62ᴾ | <<locked>> | 100% | 56,942 psi | 89% | 3399 fps | 99.1% |
| ReloadSwiss RS 70ᴾ | <<locked>> | 100% | 57,043 psi | 89% | 3438 fps | 99% |
| Rottweil R 901 | <<locked>> | 86% | 56,391 psi | 88% | 3258 fps | 100% |
| Rottweil R 902 | <<locked>> | 90% | 56,362 psi | 88% | 3271 fps | 100% |
| Rottweil R 903 | <<locked>> | 94% | 55,172 psi | 86% | 3297 fps | 99.9% |
| Rottweil R 907 | <<locked>> | 96% | 55,724 psi | 87% | 3271 fps | 96.2% |
| Shooters World Long Rifle | <<locked>> | 98% | 56,739 psi | 89% | 3297 fps | 98.2% |
| Shooters World Match Rifle | <<locked>> | 88% | 57,101 psi | 89% | 3304 fps | 100% |
| Shooters World Precision | <<locked>> | 92% | 57,508 psi | 90% | 3307 fps | 100% |
| Shooters World SW4350 | <<locked>> | 98% | 54,346 psi | 85% | 3271 fps | 96.8% |
| SNPE Vectan SP 11 | <<locked>> | 94% | 57,566 psi | 90% | 3373 fps | 99.8% |
| SNPE Vectan SP 7 | <<locked>> | 86% | 54,926 psi | 86% | 3264 fps | 98.5% |
| SNPE Vectan SP 9 | <<locked>> | 88% | 55,782 psi | 87% | 3297 fps | 99.7% |
| SNPE Vectan Tubal 3000 | <<locked>> | 88% | 57,493 psi | 90% | 3212 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 92% | 54,404 psi | 85% | 3156 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 98% | 57,638 psi | 90% | 3248 fps | 97.2% |
| Somchem S321 | <<locked>> | 82% | 53,766 psi | 84% | 3251 fps | 100% |
| Somchem S335 | <<locked>> | 88% | 56,724 psi | 89% | 3205 fps | 100% |
| Somchem S341 | <<locked>> | 86% | 54,810 psi | 86% | 3258 fps | 99.6% |
| Somchem S355 | <<locked>> | 94% | 55,622 psi | 87% | 3297 fps | 99.8% |
| Somchem S365ᴾ | <<locked>> | 100% | 50,227 psi | 79% | 3301 fps | 100% |
| Vihtavuori N130 | <<locked>> | 84% | 56,985 psi | 89% | 3176 fps | 100% |
| Vihtavuori N133 | <<locked>> | 88% | 57,696 psi | 90% | 3196 fps | 100% |
| Vihtavuori N135 | <<locked>> | 90% | 56,043 psi | 88% | 3235 fps | 100% |
| Vihtavuori N140 | <<locked>> | 90% | 57,000 psi | 89% | 3251 fps | 100% |
| Vihtavuori N150 | <<locked>> | 96% | 57,479 psi | 90% | 3281 fps | 100% |
| Vihtavuori N160 | <<locked>> | 98% | 55,114 psi | 86% | 3304 fps | 98.9% |
| Vihtavuori N530 | <<locked>> | 86% | 56,681 psi | 89% | 3281 fps | 100% |
| Vihtavuori N540 | <<locked>> | 90% | 55,419 psi | 87% | 3245 fps | 100% |
| Vihtavuori N550 | <<locked>> | 98% | 54,099 psi | 85% | 3304 fps | 98.7% |
| Vihtavuori N555ᴾ | <<locked>> | 100% | 42,540 psi | 67% | 3143 fps | 97.3% |
| Winchester 6.5 StaBALL | <<locked>> | 98% | 55,724 psi | 87% | 3281 fps | 100% |
| Winchester 748 | <<locked>> | 86% | 57,058 psi | 89% | 3337 fps | 100% |
| Winchester 760 | <<locked>> | 98% | 56,695 psi | 89% | 3379 fps | 97.2% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 34,650 psi | 54% | 3025 fps | 96.5% |
| Winchester StaBALL Match | <<locked>> | 88% | 55,709 psi | 87% | 3307 fps | 99.9% |
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% | 47,572 psi | 75% | 3064 fps | 100% |
| Accurate 2460 | <<locked>> | 80% | 52,576 psi | 82% | 3192 fps | 100% |
| Accurate 2495 | <<locked>> | 80% | 40,147 psi | 63% | 2959 fps | 100% |
| Accurate 2520 | <<locked>> | 80% | 47,732 psi | 75% | 3140 fps | 100% |
| Accurate 2700 | <<locked>> | 88% | 52,518 psi | 82% | 3169 fps | 95.2% |
| Accurate 4064 | <<locked>> | 80% | 37,942 psi | 59% | 2943 fps | 99.6% |
| Accurate 4350 | <<locked>> | 90% | 39,900 psi | 63% | 3041 fps | 95.8% |
| ADI AR 2206H | <<locked>> | 80% | 44,193 psi | 69% | 3084 fps | 98.1% |
| ADI AR 2208 | <<locked>> | 80% | 37,362 psi | 59% | 2904 fps | 95.5% |
| ADI Benchmark 8208 | <<locked>> | 80% | 46,311 psi | 73% | 3100 fps | 99.3% |
| Alliant AR-Comp | <<locked>> | 80% | 46,456 psi | 73% | 3097 fps | 100% |
| Alliant Power Pro 2000-MR | 44.9 gr | 80% | 40,147 psi | 63% | 3097 fps | 96.1% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 36,985 psi | 58% | 2927 fps | 97.1% |
| Alliant Reloder-10x | <<locked>> | 80% | 53,708 psi | 84% | 3182 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 80% | 39,842 psi | 62% | 2999 fps | 96.5% |
| Alliant Reloder-16 | <<locked>> | 90% | 39,566 psi | 62% | 3054 fps | 95.8% |
| Alliant Reloder-17 | 45.4 gr | 82% | 34,389 psi | 54% | 2940 fps | 95.6% |
| Alliant Reloder-23 | <<locked>> | 96% | 34,055 psi | 53% | 2923 fps | 95.4% |
| Alliant Reloder-26 | <<locked>> | 98% | 40,509 psi | 63% | 3150 fps | 95.3% |
| Baschieri & Pellagri 107 | <<locked>> | 80% | 43,598 psi | 68% | 3081 fps | 97% |
| Bofors RP3 | <<locked>> | 80% | 36,434 psi | 57% | 2923 fps | 97.1% |
| Bofors RP7 | <<locked>> | 94% | 52,025 psi | 82% | 3205 fps | 95.4% |
| Hodgdon Benchmark | <<locked>> | 80% | 47,892 psi | 75% | 3094 fps | 99.8% |
| Hodgdon BL-C2 | <<locked>> | 80% | 45,121 psi | 71% | 3114 fps | 99.5% |
| Hodgdon CFE223 | <<locked>> | 80% | 50,198 psi | 79% | 3284 fps | 98.8% |
| Hodgdon H322 | <<locked>> | 80% | 52,968 psi | 83% | 3219 fps | 100% |
| Hodgdon H380 | <<locked>> | 82% | 40,234 psi | 63% | 2995 fps | 95.2% |
| Hodgdon H414 | <<locked>> | 94% | 49,327 psi | 77% | 3241 fps | 95.5% |
| Hodgdon H4895 | <<locked>> | 80% | 44,599 psi | 70% | 3100 fps | 98.7% |
| Hodgdon Hybrid 100V | <<locked>> | 88% | 34,011 psi | 53% | 2867 fps | 95.6% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 40,770 psi | 64% | 3058 fps | 98.3% |
| Hodgdon Superformance | <<locked>> | 94% | 49,908 psi | 78% | 3268 fps | 95% |
| Hodgdon TrailBoss | <<locked>> | 80% | 26,020 psi | 41% | 1850 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 42,685 psi | 67% | 3041 fps | 98.2% |
| IMR 3031 | <<locked>> | 80% | 44,237 psi | 69% | 3104 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 39,189 psi | 61% | 2943 fps | 96.4% |
| IMR 4166 Enduron | <<locked>> | 86% | 50,995 psi | 80% | 3163 fps | 95.8% |
| IMR 4198 | <<locked>> | 80% | 53,737 psi | 84% | 3143 fps | 100% |
| IMR 4350 | <<locked>> | 98% | 52,692 psi | 83% | 3235 fps | 95.6% |
| IMR 4451 Enduron | <<locked>> | 92% | 50,821 psi | 80% | 3186 fps | 95.6% |
| IMR 4831 | <<locked>> | 90% | 38,247 psi | 60% | 2982 fps | 95.3% |
| IMR 4895 | <<locked>> | 80% | 40,828 psi | 64% | 3035 fps | 97.4% |
| IMR 8208 XBR | <<locked>> | 80% | 46,311 psi | 73% | 3100 fps | 99.3% |
| Lovex D073.5 | <<locked>> | 80% | 52,649 psi | 83% | 3202 fps | 100% |
| Lovex D073.6 | <<locked>> | 80% | 43,294 psi | 68% | 3061 fps | 99.8% |
| Lovex S060 | <<locked>> | 80% | 44,106 psi | 69% | 3018 fps | 98.2% |
| Lovex S062 | <<locked>> | 80% | 39,001 psi | 61% | 2949 fps | 98.1% |
| Lovex S065 | <<locked>> | 90% | 44,106 psi | 69% | 3054 fps | 95.5% |
| Lovex S070 | <<locked>> | 94% | 47,703 psi | 75% | 3146 fps | 95.2% |
| Norma 201 | <<locked>> | 80% | 43,134 psi | 68% | 3031 fps | 98.9% |
| Norma 202 | <<locked>> | 80% | 43,482 psi | 68% | 3045 fps | 99.9% |
| Norma 203B | <<locked>> | 80% | 39,233 psi | 61% | 2989 fps | 96.9% |
| Norma URP | <<locked>> | 90% | 39,856 psi | 62% | 3038 fps | 95.6% |
| Ramshot Big Game | <<locked>> | 80% | 38,827 psi | 61% | 2995 fps | 96.6% |
| Ramshot Hunter | <<locked>> | 94% | 44,947 psi | 70% | 3156 fps | 95.2% |
| Ramshot TAC | <<locked>> | 80% | 46,398 psi | 73% | 3097 fps | 96.3% |
| Ramshot Wild Boar | <<locked>> | 80% | 45,934 psi | 72% | 3123 fps | 98.5% |
| Ramshot X-Terminator | <<locked>> | 80% | 50,024 psi | 78% | 3153 fps | 99% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 26,353 psi | 41% | 1896 fps | 100% |
| ReloadSwiss RS 40 | <<locked>> | 80% | 51,938 psi | 81% | 3202 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 86% | 46,702 psi | 73% | 3107 fps | 95.4% |
| ReloadSwiss RS 52 | <<locked>> | 80% | 42,105 psi | 66% | 3117 fps | 97% |
| ReloadSwiss RS 60 | 44.2 gr | 80% | 33,997 psi | 53% | 2946 fps | 98% |
| ReloadSwiss RS 62 | <<locked>> | 90% | 39,639 psi | 62% | 3054 fps | 95.3% |
| ReloadSwiss RS 70 | <<locked>> | 92% | 42,888 psi | 67% | 3143 fps | 95.6% |
| Rottweil R 901 | <<locked>> | 80% | 46,862 psi | 73% | 3091 fps | 100% |
| Rottweil R 902 | <<locked>> | 80% | 40,973 psi | 64% | 2976 fps | 98.5% |
| Rottweil R 903 | <<locked>> | 80% | 34,185 psi | 54% | 2854 fps | 96% |
| Rottweil R 907 | <<locked>> | 94% | 52,025 psi | 82% | 3205 fps | 95.4% |
| Shooters World Long Rifle | <<locked>> | 90% | 44,106 psi | 69% | 3054 fps | 95.5% |
| Shooters World Match Rifle | <<locked>> | 80% | 43,294 psi | 68% | 3061 fps | 99.8% |
| Shooters World Precision | <<locked>> | 80% | 39,001 psi | 61% | 2949 fps | 98.1% |
| Shooters World SW4350 | <<locked>> | 94% | 47,703 psi | 75% | 3146 fps | 95.2% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 35,592 psi | 56% | 2917 fps | 95.5% |
| SNPE Vectan SP 7 | <<locked>> | 80% | 44,643 psi | 70% | 3064 fps | 96.4% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 42,844 psi | 67% | 3048 fps | 97.8% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 44,527 psi | 70% | 2992 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 36,985 psi | 58% | 2831 fps | 99.8% |
| SNPE Vectan Tubal 7000 | <<locked>> | 94% | 50,401 psi | 79% | 3123 fps | 95.7% |
| Somchem S321 | <<locked>> | 80% | 50,285 psi | 79% | 3192 fps | 99.8% |
| Somchem S335 | <<locked>> | 80% | 44,179 psi | 69% | 2992 fps | 100% |
| Somchem S341 | <<locked>> | 80% | 44,382 psi | 70% | 3064 fps | 98.1% |
| Somchem S355 | <<locked>> | 80% | 35,244 psi | 55% | 2871 fps | 96.1% |
| Somchem S365 | <<locked>> | 86% | 31,053 psi | 49% | 2844 fps | 95.9% |
| Vihtavuori N130 | <<locked>> | 80% | 50,314 psi | 79% | 3071 fps | 100% |
| Vihtavuori N133 | <<locked>> | 80% | 44,904 psi | 70% | 2992 fps | 100% |
| Vihtavuori N135 | <<locked>> | 80% | 40,393 psi | 63% | 2966 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 41,104 psi | 64% | 2969 fps | 99.9% |
| Vihtavuori N150 | <<locked>> | 80% | 33,431 psi | 52% | 2799 fps | 97% |
| Vihtavuori N160 | <<locked>> | 88% | 39,131 psi | 61% | 2982 fps | 95.3% |
| Vihtavuori N530 | <<locked>> | 80% | 46,253 psi | 72% | 3094 fps | 99.4% |
| Vihtavuori N540 | <<locked>> | 80% | 39,711 psi | 62% | 2953 fps | 99.6% |
| Vihtavuori N550 | <<locked>> | 90% | 41,292 psi | 65% | 3045 fps | 95.8% |
| Vihtavuori N555 | <<locked>> | 96% | 36,883 psi | 58% | 3012 fps | 95.5% |
| Winchester 6.5 StaBALL | <<locked>> | 84% | 34,316 psi | 54% | 2831 fps | 96% |
| Winchester 748 | <<locked>> | 80% | 46,296 psi | 73% | 3146 fps | 99.8% |
| Winchester 760 | <<locked>> | 94% | 49,327 psi | 77% | 3241 fps | 95.5% |
| Winchester StaBALL HD | <<locked>> | 98% | 32,532 psi | 51% | 2946 fps | 95% |
| Winchester StaBALL Match | <<locked>> | 80% | 42,322 psi | 66% | 3048 fps | 98.3% |
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 99 powders for .255 GS loaded with the .257 | 90gr | Hornady GMX. Alliant Power Pro 2000-MR delivers the highest muzzle velocity at 3,465 fps; across all powders the maximum-charge window runs from 2,070 fps to 3,465 fps. Accurate 4350 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 54–90 %, leaving at least 10 % headroom. The 90.0 gr projectile in 0.257" calls for a 1:10.5 twist; slower twists will usually not stabilise this weight. Accurate 4350, Alliant Reloder-16, 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. Alliant Power Pro 2000-MR, ReloadSwiss RS 60, Alliant Reloder-17 rank at the top here: for .255 GS with the .257 | 90gr | Hornady GMX 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.