Load Specifications
Load data in caliber .255 GS with .257 | 100gr | Winchester Silvertip bullet and 96 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are ReloadSwiss RS 70, Alliant Reloder-17 and ReloadSwiss RS 60.
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% | 56,202 psi | 88% | 3045 fps | 100% |
| Accurate 2495 | <<locked>> | 86% | 55,680 psi | 87% | 3071 fps | 100% |
| Accurate 2520 | <<locked>> | 82% | 57,000 psi | 89% | 3140 fps | 100% |
| Accurate 2700 | <<locked>> | 86% | 54,259 psi | 85% | 3068 fps | 96.9% |
| Accurate 3100ᴾ | <<locked>> | 100% | 46,731 psi | 73% | 3018 fps | 97.1% |
| Accurate 4064 | <<locked>> | 88% | 55,738 psi | 87% | 3123 fps | 100% |
| Accurate 4350 | <<locked>> | 96% | 56,420 psi | 88% | 3219 fps | 99.7% |
| ADI AR 2206H | <<locked>> | 84% | 55,347 psi | 87% | 3153 fps | 99.9% |
| ADI AR 2208 | <<locked>> | 90% | 56,550 psi | 89% | 3153 fps | 99.9% |
| ADI AR 2209ᴾ | <<locked>> | 100% | 54,114 psi | 85% | 3186 fps | 95.9% |
| ADI Benchmark 8208 | <<locked>> | 84% | 57,696 psi | 90% | 3153 fps | 100% |
| Alliant AR-Comp | <<locked>> | 82% | 55,695 psi | 87% | 3077 fps | 100% |
| Alliant Power Pro 2000-MR | <<locked>> | 86% | 55,390 psi | 87% | 3281 fps | 99.9% |
| Alliant Reloder- TS 15.5 | <<locked>> | 90% | 56,942 psi | 89% | 3179 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 88% | 57,319 psi | 90% | 3202 fps | 99.9% |
| Alliant Reloder-16 | <<locked>> | 98% | 57,072 psi | 89% | 3281 fps | 99.9% |
| Alliant Reloder-17 | <<locked>> | 92% | 54,636 psi | 86% | 3255 fps | 100% |
| Alliant Reloder-19ᴾ | <<locked>> | 100% | 53,142 psi | 83% | 3173 fps | 95.9% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 43,903 psi | 69% | 3045 fps | 99.5% |
| Alliant Reloder-26ᴾ | <<locked>> | 100% | 50,241 psi | 79% | 3241 fps | 99.2% |
| Baschieri & Pellagri 107 | <<locked>> | 84% | 55,390 psi | 87% | 3166 fps | 99.7% |
| Bofors RP3 | <<locked>> | 88% | 54,056 psi | 85% | 3136 fps | 100% |
| Bofors RP7 | <<locked>> | 94% | 57,595 psi | 90% | 3169 fps | 97.7% |
| Hodgdon Benchmark | <<locked>> | 82% | 55,637 psi | 87% | 3081 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 84% | 57,711 psi | 90% | 3186 fps | 100% |
| Hodgdon H380 | <<locked>> | 88% | 55,114 psi | 86% | 3156 fps | 99.3% |
| Hodgdon H414 | <<locked>> | 94% | 55,071 psi | 86% | 3209 fps | 97.9% |
| Hodgdon H4350 | <<locked>> | 92% | 55,361 psi | 87% | 3169 fps | 96.7% |
| Hodgdon H4895 | <<locked>> | 84% | 55,985 psi | 88% | 3163 fps | 100% |
| Hodgdon Hybrid 100Vᴾ | <<locked>> | 100% | 57,348 psi | 90% | 3199 fps | 100% |
| Hodgdon LEVERevolution | <<locked>> | 86% | 55,956 psi | 88% | 3199 fps | 100% |
| Hodgdon Superformance | <<locked>> | 94% | 55,564 psi | 87% | 3245 fps | 97.7% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 35,766 psi | 56% | 1975 fps | 100% |
| Hodgdon VARGET | <<locked>> | 86% | 57,087 psi | 89% | 3166 fps | 100% |
| IMR 3031 | <<locked>> | 84% | 56,231 psi | 88% | 3146 fps | 100% |
| IMR 4064 | <<locked>> | 88% | 56,130 psi | 88% | 3140 fps | 99.9% |
| IMR 4166 Enduron | <<locked>> | 86% | 55,550 psi | 87% | 3114 fps | 97.9% |
| IMR 4350 | <<locked>> | 96% | 54,694 psi | 86% | 3136 fps | 97.3% |
| IMR 4451 Enduron | <<locked>> | 92% | 55,941 psi | 88% | 3143 fps | 97.8% |
| IMR 4831 | <<locked>> | 98% | 56,739 psi | 89% | 3209 fps | 99.8% |
| IMR 4895 | <<locked>> | 86% | 55,332 psi | 87% | 3179 fps | 100% |
| IMR 8208 XBR | <<locked>> | 84% | 57,696 psi | 90% | 3153 fps | 100% |
| Lovex D073.6 | <<locked>> | 84% | 55,680 psi | 87% | 3127 fps | 100% |
| Lovex S060 | <<locked>> | 84% | 54,549 psi | 85% | 3074 fps | 99.9% |
| Lovex S062 | <<locked>> | 88% | 56,159 psi | 88% | 3133 fps | 100% |
| Lovex S065 | <<locked>> | 94% | 55,419 psi | 87% | 3133 fps | 98.9% |
| Lovex S070 | <<locked>> | 96% | 56,666 psi | 89% | 3173 fps | 98.3% |
| Norma 201 | <<locked>> | 86% | 57,667 psi | 90% | 3150 fps | 100% |
| Norma 202 | <<locked>> | 84% | 54,810 psi | 86% | 3097 fps | 100% |
| Norma 203B | <<locked>> | 88% | 56,536 psi | 89% | 3186 fps | 100% |
| Norma 204 | <<locked>> | 96% | 55,288 psi | 87% | 3186 fps | 96.1% |
| Norma MRPᴾ | <<locked>> | 100% | 49,516 psi | 78% | 3186 fps | 96.7% |
| Norma URP | <<locked>> | 96% | 54,926 psi | 86% | 3199 fps | 99.5% |
| Ramshot Big Game | <<locked>> | 88% | 57,682 psi | 90% | 3219 fps | 100% |
| Ramshot Hunter | <<locked>> | 98% | 57,580 psi | 90% | 3255 fps | 98.9% |
| Ramshot TAC | <<locked>> | 82% | 54,592 psi | 86% | 3117 fps | 98.9% |
| Ramshot Wild Boar | <<locked>> | 82% | 54,230 psi | 85% | 3133 fps | 99.9% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 36,463 psi | 57% | 2024 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 88% | 55,042 psi | 86% | 3130 fps | 98.3% |
| ReloadSwiss RS 52 | <<locked>> | 84% | 54,578 psi | 86% | 3219 fps | 99.8% |
| ReloadSwiss RS 60 | <<locked>> | 90% | 54,259 psi | 85% | 3255 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 96% | 56,101 psi | 88% | 3238 fps | 99.6% |
| ReloadSwiss RS 70 | <<locked>> | 96% | 55,230 psi | 87% | 3268 fps | 99.4% |
| Rottweil R 901 | <<locked>> | 82% | 55,056 psi | 86% | 3077 fps | 100% |
| Rottweil R 902 | <<locked>> | 86% | 54,955 psi | 86% | 3097 fps | 100% |
| Rottweil R 903 | <<locked>> | 92% | 57,725 psi | 90% | 3186 fps | 100% |
| Rottweil R 907 | <<locked>> | 94% | 57,595 psi | 90% | 3169 fps | 97.7% |
| Shooters World Long Rifle | <<locked>> | 94% | 55,419 psi | 87% | 3133 fps | 98.9% |
| Shooters World Match Rifle | <<locked>> | 84% | 55,680 psi | 87% | 3127 fps | 100% |
| Shooters World Precision | <<locked>> | 88% | 56,159 psi | 88% | 3133 fps | 100% |
| Shooters World SW4350 | <<locked>> | 96% | 56,666 psi | 89% | 3173 fps | 98.3% |
| SNPE Vectan SP 11 | <<locked>> | 90% | 55,782 psi | 87% | 3192 fps | 100% |
| SNPE Vectan SP 7 | <<locked>> | 84% | 57,000 psi | 89% | 3156 fps | 99.4% |
| SNPE Vectan SP 9 | <<locked>> | 86% | 57,653 psi | 90% | 3179 fps | 100% |
| SNPE Vectan Tubal 3000 | <<locked>> | 84% | 55,288 psi | 87% | 3031 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 90% | 55,912 psi | 88% | 3028 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 94% | 55,593 psi | 87% | 3084 fps | 97.9% |
| Somchem S335 | <<locked>> | 84% | 55,042 psi | 86% | 3028 fps | 100% |
| Somchem S341 | <<locked>> | 84% | 56,449 psi | 88% | 3140 fps | 100% |
| Somchem S355 | <<locked>> | 90% | 54,491 psi | 85% | 3133 fps | 100% |
| Somchem S365ᴾ | <<locked>> | 100% | 57,348 psi | 90% | 3261 fps | 100% |
| Somchem S385ᴾ | <<locked>> | 100% | 52,982 psi | 83% | 3133 fps | 96.9% |
| Vihtavuori N133 | <<locked>> | 84% | 55,666 psi | 87% | 3015 fps | 100% |
| Vihtavuori N135 | <<locked>> | 86% | 54,723 psi | 86% | 3058 fps | 100% |
| Vihtavuori N140 | <<locked>> | 86% | 55,434 psi | 87% | 3074 fps | 100% |
| Vihtavuori N150 | <<locked>> | 92% | 55,709 psi | 87% | 3104 fps | 100% |
| Vihtavuori N160 | <<locked>> | 96% | 57,537 psi | 90% | 3199 fps | 99.7% |
| Vihtavuori N530 | <<locked>> | 82% | 54,549 psi | 85% | 3097 fps | 100% |
| Vihtavuori N540 | <<locked>> | 88% | 57,334 psi | 90% | 3123 fps | 100% |
| Vihtavuori N550 | <<locked>> | 96% | 56,637 psi | 89% | 3202 fps | 99.6% |
| Vihtavuori N555ᴾ | <<locked>> | 100% | 49,110 psi | 77% | 3133 fps | 99.4% |
| Winchester 6.5 StaBALL | <<locked>> | 96% | 57,551 psi | 90% | 3166 fps | 100% |
| Winchester 748 | <<locked>> | 82% | 55,027 psi | 86% | 3150 fps | 100% |
| Winchester 760 | <<locked>> | 94% | 55,405 psi | 87% | 3212 fps | 98% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 39,610 psi | 62% | 3064 fps | 99.6% |
| Winchester StaBALL Match | <<locked>> | 84% | 53,795 psi | 84% | 3127 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% | 52,866 psi | 83% | 2995 fps | 100% |
| Accurate 2495 | <<locked>> | 80% | 45,745 psi | 72% | 2917 fps | 100% |
| Accurate 2520 | <<locked>> | 80% | 53,229 psi | 83% | 3081 fps | 100% |
| Accurate 2700 | <<locked>> | 82% | 47,529 psi | 74% | 2946 fps | 95.3% |
| Accurate 3100 | <<locked>> | 96% | 40,698 psi | 64% | 2894 fps | 95.4% |
| Accurate 4064 | <<locked>> | 80% | 43,250 psi | 68% | 2910 fps | 100% |
| Accurate 4350 | <<locked>> | 82% | 34,577 psi | 54% | 2776 fps | 95.1% |
| ADI AR 2206H | <<locked>> | 80% | 48,805 psi | 76% | 3035 fps | 99.5% |
| ADI AR 2208 | <<locked>> | 80% | 41,553 psi | 65% | 2871 fps | 97.9% |
| ADI AR 2209 | <<locked>> | 98% | 50,517 psi | 79% | 3117 fps | 95% |
| ADI Benchmark 8208 | <<locked>> | 80% | 50,879 psi | 80% | 3041 fps | 100% |
| Alliant AR-Comp | <<locked>> | 80% | 51,866 psi | 81% | 3022 fps | 100% |
| Alliant Power Pro 2000-MR | <<locked>> | 80% | 45,063 psi | 71% | 3077 fps | 98.7% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 41,437 psi | 65% | 2894 fps | 99.1% |
| Alliant Reloder-15 | <<locked>> | 80% | 44,411 psi | 70% | 2966 fps | 98.6% |
| Alliant Reloder-16 | <<locked>> | 82% | 34,229 psi | 54% | 2785 fps | 95.1% |
| Alliant Reloder-17 | 44.4 gr | 80% | 36,114 psi | 57% | 2864 fps | 97.7% |
| Alliant Reloder-19 | <<locked>> | 98% | 49,705 psi | 78% | 3107 fps | 95% |
| Alliant Reloder-23 | <<locked>> | 90% | 32,068 psi | 50% | 2746 fps | 96% |
| Alliant Reloder-26 | <<locked>> | 92% | 37,405 psi | 59% | 2946 fps | 95.6% |
| Baschieri & Pellagri 107 | <<locked>> | 80% | 48,312 psi | 76% | 3041 fps | 98.9% |
| Bofors RP3 | <<locked>> | 80% | 41,553 psi | 65% | 2904 fps | 99.2% |
| Bofors RP7 | <<locked>> | 88% | 47,732 psi | 75% | 2989 fps | 95.6% |
| Hodgdon Benchmark | <<locked>> | 80% | 52,489 psi | 82% | 3028 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 80% | 50,502 psi | 79% | 3071 fps | 100% |
| Hodgdon H380 | <<locked>> | 80% | 42,018 psi | 66% | 2904 fps | 97% |
| Hodgdon H414 | <<locked>> | 88% | 45,194 psi | 71% | 3018 fps | 95.7% |
| Hodgdon H4350 | <<locked>> | 88% | 48,501 psi | 76% | 3041 fps | 95% |
| Hodgdon H4895 | <<locked>> | 80% | 49,284 psi | 77% | 3048 fps | 99.8% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 29,573 psi | 46% | 2615 fps | 95% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 45,672 psi | 72% | 3018 fps | 99.7% |
| Hodgdon Superformance | <<locked>> | 90% | 48,182 psi | 76% | 3107 fps | 96% |
| Hodgdon TrailBoss | <<locked>> | 80% | 26,803 psi | 42% | 1772 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 47,297 psi | 74% | 2995 fps | 99.6% |
| IMR 3031 | <<locked>> | 80% | 49,472 psi | 78% | 3041 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 43,642 psi | 68% | 2910 fps | 98.6% |
| IMR 4166 Enduron | <<locked>> | 80% | 45,919 psi | 72% | 2930 fps | 95.8% |
| IMR 4350 | <<locked>> | 92% | 48,211 psi | 76% | 3018 fps | 95.8% |
| IMR 4451 Enduron | <<locked>> | 84% | 43,598 psi | 68% | 2907 fps | 95% |
| IMR 4831 | <<locked>> | 84% | 35,607 psi | 56% | 2785 fps | 95.7% |
| IMR 4895 | <<locked>> | 80% | 45,513 psi | 71% | 2999 fps | 99.2% |
| IMR 8208 XBR | <<locked>> | 80% | 50,879 psi | 80% | 3041 fps | 100% |
| Lovex D073.6 | <<locked>> | 80% | 48,559 psi | 76% | 3015 fps | 100% |
| Lovex S060 | <<locked>> | 80% | 48,414 psi | 76% | 2966 fps | 99.5% |
| Lovex S062 | <<locked>> | 80% | 43,772 psi | 69% | 2913 fps | 99.6% |
| Lovex S065 | <<locked>> | 84% | 40,872 psi | 64% | 2851 fps | 95.8% |
| Lovex S070 | <<locked>> | 88% | 43,976 psi | 69% | 2936 fps | 95.5% |
| Norma 201 | <<locked>> | 80% | 47,819 psi | 75% | 2982 fps | 99.9% |
| Norma 202 | <<locked>> | 80% | 48,182 psi | 76% | 2986 fps | 100% |
| Norma 203B | <<locked>> | 80% | 43,758 psi | 69% | 2953 fps | 98.9% |
| Norma 204 | <<locked>> | 94% | 51,576 psi | 81% | 3120 fps | 95.2% |
| Norma MRP | <<locked>> | 98% | 46,209 psi | 72% | 3120 fps | 95.8% |
| Norma URP | <<locked>> | 82% | 34,621 psi | 54% | 2776 fps | 95% |
| Ramshot Big Game | <<locked>> | 80% | 43,801 psi | 69% | 2969 fps | 98.8% |
| Ramshot Hunter | <<locked>> | 88% | 41,336 psi | 65% | 2943 fps | 95.5% |
| Ramshot TAC | <<locked>> | 80% | 50,894 psi | 80% | 3051 fps | 98.3% |
| Ramshot Wild Boar | <<locked>> | 80% | 50,734 psi | 80% | 3074 fps | 99.7% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 27,021 psi | 42% | 1811 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 42,308 psi | 66% | 2884 fps | 95.4% |
| ReloadSwiss RS 52 | <<locked>> | 80% | 47,471 psi | 74% | 3087 fps | 99.1% |
| ReloadSwiss RS 60 | 44.4 gr | 80% | 38,421 psi | 60% | 2936 fps | 99.8% |
| ReloadSwiss RS 62 | <<locked>> | 84% | 36,637 psi | 57% | 2848 fps | 95.5% |
| ReloadSwiss RS 70 | 48.4 gr | 86% | 38,827 psi | 61% | 2920 fps | 95.6% |
| Rottweil R 901 | <<locked>> | 80% | 51,851 psi | 81% | 3028 fps | 100% |
| Rottweil R 902 | <<locked>> | 80% | 45,527 psi | 71% | 2930 fps | 99.7% |
| Rottweil R 903 | <<locked>> | 80% | 38,856 psi | 61% | 2838 fps | 98.5% |
| Rottweil R 907 | <<locked>> | 88% | 47,732 psi | 75% | 2989 fps | 95.6% |
| Shooters World Long Rifle | <<locked>> | 84% | 40,872 psi | 64% | 2851 fps | 95.8% |
| Shooters World Match Rifle | <<locked>> | 80% | 48,559 psi | 76% | 3015 fps | 100% |
| Shooters World Precision | <<locked>> | 80% | 43,772 psi | 69% | 2913 fps | 99.6% |
| Shooters World SW4350 | <<locked>> | 88% | 43,976 psi | 69% | 2936 fps | 95.5% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 40,016 psi | 63% | 2894 fps | 98.1% |
| SNPE Vectan SP 7 | <<locked>> | 80% | 49,559 psi | 78% | 3028 fps | 98.5% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 47,355 psi | 74% | 3002 fps | 99.4% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 48,791 psi | 76% | 2927 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 40,944 psi | 64% | 2776 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 86% | 42,902 psi | 67% | 2848 fps | 95% |
| Somchem S335 | <<locked>> | 80% | 48,573 psi | 76% | 2927 fps | 100% |
| Somchem S341 | <<locked>> | 80% | 49,139 psi | 77% | 3018 fps | 99.6% |
| Somchem S355 | <<locked>> | 80% | 39,639 psi | 62% | 2844 fps | 98.5% |
| Somchem S365 | <<locked>> | 80% | 29,080 psi | 46% | 2657 fps | 96.4% |
| Somchem S385 | <<locked>> | 96% | 46,209 psi | 72% | 3005 fps | 95.2% |
| Vihtavuori N133 | <<locked>> | 80% | 49,211 psi | 77% | 2917 fps | 100% |
| Vihtavuori N135 | <<locked>> | 80% | 45,237 psi | 71% | 2907 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 45,600 psi | 71% | 2913 fps | 100% |
| Vihtavuori N150 | <<locked>> | 80% | 37,594 psi | 59% | 2769 fps | 99.1% |
| Vihtavuori N160 | <<locked>> | 82% | 36,158 psi | 57% | 2779 fps | 95.6% |
| Vihtavuori N530 | <<locked>> | 80% | 51,271 psi | 80% | 3041 fps | 100% |
| Vihtavuori N540 | <<locked>> | 80% | 44,092 psi | 69% | 2900 fps | 100% |
| Vihtavuori N550 | <<locked>> | 82% | 35,592 psi | 56% | 2776 fps | 95.1% |
| Vihtavuori N555 | <<locked>> | 88% | 32,663 psi | 51% | 2762 fps | 95.1% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 33,359 psi | 52% | 2687 fps | 97% |
| Winchester 748 | <<locked>> | 80% | 51,459 psi | 81% | 3091 fps | 100% |
| Winchester 760 | <<locked>> | 88% | 45,194 psi | 71% | 3018 fps | 95.7% |
| Winchester StaBALL HD | <<locked>> | 92% | 30,284 psi | 47% | 2769 fps | 95.7% |
| Winchester StaBALL Match | <<locked>> | 80% | 47,050 psi | 74% | 3005 fps | 99.6% |
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 96 powders for .255 GS loaded with the .257 | 100gr | Winchester Silvertip. Alliant Power Pro 2000-MR delivers the highest muzzle velocity at 3,281 fps; across all powders the maximum-charge window runs from 1,975 fps to 3,281 fps. Accurate 3100 gives the best case fill at 100 %, and 96 of the 96 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 1:11.5 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. ReloadSwiss RS 70, Alliant Reloder-17, ReloadSwiss RS 60 rank at the top here: for .255 GS with the .257 | 100gr | Winchester Silvertip 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.