Load Specifications
Load data in caliber .255 GS with .257 | 87gr | Frontier PH HPFB bullet and 97 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% | 54,969 psi | 86% | 3228 fps | 100% |
| Accurate 2460 | <<locked>> | 82% | 57,232 psi | 90% | 3307 fps | 100% |
| Accurate 2495 | <<locked>> | 90% | 57,479 psi | 90% | 3301 fps | 100% |
| Accurate 2520 | <<locked>> | 84% | 55,666 psi | 87% | 3320 fps | 100% |
| Accurate 2700 | <<locked>> | 90% | 56,956 psi | 89% | 3287 fps | 95.9% |
| Accurate 4064 | <<locked>> | 92% | 57,638 psi | 90% | 3353 fps | 100% |
| Accurate 4350 | <<locked>> | 98% | 53,809 psi | 84% | 3363 fps | 98.7% |
| ADI AR 2206H | <<locked>> | 86% | 54,172 psi | 85% | 3323 fps | 99.4% |
| ADI AR 2208 | <<locked>> | 92% | 55,390 psi | 87% | 3323 fps | 99.2% |
| ADI Benchmark 8208 | <<locked>> | 86% | 56,623 psi | 89% | 3333 fps | 100% |
| Alliant AR-Comp | <<locked>> | 86% | 57,464 psi | 90% | 3314 fps | 100% |
| Alliant Power Pro 2000-MR | <<locked>> | 88% | 54,143 psi | 85% | 3448 fps | 99.1% |
| Alliant Reloder- TS 15.5 | <<locked>> | 92% | 55,332 psi | 87% | 3350 fps | 99.9% |
| Alliant Reloder-15 | <<locked>> | 90% | 56,101 psi | 88% | 3376 fps | 99.4% |
| Alliant Reloder-16ᴾ | <<locked>> | 100% | 55,071 psi | 86% | 3432 fps | 99.2% |
| Alliant Reloder-17 | <<locked>> | 96% | 56,753 psi | 89% | 3481 fps | 99.9% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 39,624 psi | 62% | 3110 fps | 97.3% |
| Alliant Reloder-26ᴾ | <<locked>> | 100% | 44,483 psi | 70% | 3284 fps | 96.4% |
| Baschieri & Pellagri 107 | <<locked>> | 86% | 54,143 psi | 85% | 3330 fps | 98.8% |
| Bofors RP3 | <<locked>> | 92% | 56,347 psi | 88% | 3366 fps | 99.9% |
| Bofors RP7 | <<locked>> | 96% | 56,188 psi | 88% | 3320 fps | 96% |
| Hodgdon Benchmark | <<locked>> | 84% | 54,955 psi | 86% | 3264 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 86% | 56,318 psi | 88% | 3363 fps | 100% |
| Hodgdon CFE223 | <<locked>> | 82% | 54,665 psi | 86% | 3412 fps | 99.2% |
| Hodgdon H322 | <<locked>> | 82% | 57,421 psi | 90% | 3337 fps | 100% |
| Hodgdon H380 | <<locked>> | 92% | 57,203 psi | 90% | 3376 fps | 98.7% |
| Hodgdon H414 | <<locked>> | 98% | 56,927 psi | 89% | 3422 fps | 96.9% |
| Hodgdon H4895 | <<locked>> | 86% | 54,694 psi | 86% | 3340 fps | 99.7% |
| Hodgdon Hybrid 100Vᴾ | <<locked>> | 100% | 51,474 psi | 81% | 3294 fps | 99.5% |
| Hodgdon LEVERevolution | <<locked>> | 88% | 54,404 psi | 85% | 3369 fps | 99.9% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 35,317 psi | 55% | 2106 fps | 100% |
| Hodgdon VARGET | <<locked>> | 88% | 56,275 psi | 88% | 3343 fps | 99.8% |
| IMR 3031 | <<locked>> | 86% | 54,708 psi | 86% | 3333 fps | 100% |
| IMR 4064 | <<locked>> | 90% | 54,984 psi | 86% | 3307 fps | 99.3% |
| IMR 4166 Enduron | <<locked>> | 88% | 54,969 psi | 86% | 3278 fps | 96.4% |
| IMR 4198 | <<locked>> | 82% | 57,609 psi | 90% | 3248 fps | 100% |
| IMR 4350ᴾ | <<locked>> | 100% | 56,579 psi | 89% | 3343 fps | 96.2% |
| IMR 4451 Enduron | <<locked>> | 94% | 54,665 psi | 86% | 3301 fps | 96.2% |
| IMR 4831ᴾ | <<locked>> | 100% | 54,665 psi | 86% | 3360 fps | 98.9% |
| IMR 4895 | <<locked>> | 90% | 57,551 psi | 90% | 3412 fps | 99.7% |
| IMR 8208 XBR | <<locked>> | 86% | 56,623 psi | 89% | 3333 fps | 100% |
| Lovex D073.5 | <<locked>> | 82% | 57,217 psi | 90% | 3317 fps | 100% |
| Lovex D073.6 | <<locked>> | 86% | 53,969 psi | 85% | 3301 fps | 100% |
| Lovex S060 | <<locked>> | 88% | 57,116 psi | 90% | 3307 fps | 99.7% |
| Lovex S062 | <<locked>> | 90% | 54,810 psi | 86% | 3307 fps | 99.9% |
| Lovex S065 | <<locked>> | 98% | 57,537 psi | 90% | 3350 fps | 98.1% |
| Lovex S070 | <<locked>> | 98% | 55,201 psi | 87% | 3330 fps | 96.7% |
| Norma 201 | <<locked>> | 88% | 56,507 psi | 89% | 3330 fps | 100% |
| Norma 202 | <<locked>> | 88% | 56,913 psi | 89% | 3330 fps | 100% |
| Norma 203B | <<locked>> | 90% | 55,274 psi | 87% | 3360 fps | 99.6% |
| Norma URPᴾ | <<locked>> | 100% | 56,507 psi | 89% | 3412 fps | 99% |
| Ramshot Big Game | <<locked>> | 90% | 55,999 psi | 88% | 3383 fps | 99.6% |
| Ramshot Hunterᴾ | <<locked>> | 100% | 55,796 psi | 87% | 3409 fps | 97.6% |
| Ramshot TAC | <<locked>> | 86% | 57,232 psi | 90% | 3343 fps | 98.2% |
| Ramshot Wild Boar | <<locked>> | 86% | 56,985 psi | 89% | 3369 fps | 99.7% |
| Ramshot X-Terminator | <<locked>> | 82% | 54,288 psi | 85% | 3274 fps | 99.4% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 35,636 psi | 56% | 2152 fps | 100% |
| ReloadSwiss RS 40 | <<locked>> | 82% | 56,231 psi | 88% | 3317 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 92% | 57,508 psi | 90% | 3353 fps | 97.5% |
| ReloadSwiss RS 52 | <<locked>> | 88% | 56,434 psi | 88% | 3445 fps | 99.4% |
| ReloadSwiss RS 60 | <<locked>> | 94% | 56,478 psi | 89% | 3488 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 98% | 54,012 psi | 85% | 3389 fps | 98.5% |
| ReloadSwiss RS 70ᴾ | <<locked>> | 100% | 57,508 psi | 90% | 3484 fps | 98.8% |
| Rottweil R 901 | <<locked>> | 86% | 57,116 psi | 90% | 3310 fps | 100% |
| Rottweil R 902 | <<locked>> | 90% | 57,130 psi | 90% | 3327 fps | 100% |
| Rottweil R 903 | <<locked>> | 94% | 56,188 psi | 88% | 3356 fps | 99.9% |
| Rottweil R 907 | <<locked>> | 96% | 56,188 psi | 88% | 3320 fps | 96% |
| Shooters World Long Rifle | <<locked>> | 98% | 57,537 psi | 90% | 3350 fps | 98.1% |
| Shooters World Match Rifle | <<locked>> | 86% | 53,969 psi | 85% | 3301 fps | 100% |
| Shooters World Precision | <<locked>> | 90% | 54,810 psi | 86% | 3307 fps | 99.9% |
| Shooters World SW4350 | <<locked>> | 98% | 55,201 psi | 87% | 3330 fps | 96.7% |
| SNPE Vectan SP 11 | <<locked>> | 92% | 54,114 psi | 85% | 3356 fps | 99.4% |
| SNPE Vectan SP 7 | <<locked>> | 86% | 55,825 psi | 87% | 3320 fps | 98.4% |
| SNPE Vectan SP 9 | <<locked>> | 88% | 56,217 psi | 88% | 3346 fps | 99.6% |
| SNPE Vectan Tubal 3000 | <<locked>> | 86% | 54,346 psi | 85% | 3209 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 92% | 54,940 psi | 86% | 3209 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 96% | 54,534 psi | 85% | 3235 fps | 96.3% |
| Somchem S321 | <<locked>> | 82% | 54,433 psi | 85% | 3307 fps | 100% |
| Somchem S335 | <<locked>> | 88% | 57,392 psi | 90% | 3258 fps | 100% |
| Somchem S341 | <<locked>> | 86% | 55,201 psi | 87% | 3310 fps | 99.5% |
| Somchem S355 | <<locked>> | 94% | 56,217 psi | 88% | 3353 fps | 99.8% |
| Somchem S365ᴾ | <<locked>> | 100% | 50,937 psi | 80% | 3356 fps | 100% |
| Vihtavuori N130 | <<locked>> | 84% | 57,348 psi | 90% | 3225 fps | 100% |
| Vihtavuori N133 | <<locked>> | 86% | 54,534 psi | 85% | 3196 fps | 100% |
| Vihtavuori N135 | <<locked>> | 90% | 56,782 psi | 89% | 3294 fps | 100% |
| Vihtavuori N140 | <<locked>> | 88% | 54,157 psi | 85% | 3251 fps | 100% |
| Vihtavuori N150 | <<locked>> | 94% | 54,447 psi | 85% | 3274 fps | 100% |
| Vihtavuori N160 | <<locked>> | 98% | 55,434 psi | 87% | 3353 fps | 98.8% |
| Vihtavuori N530 | <<locked>> | 86% | 57,246 psi | 90% | 3333 fps | 100% |
| Vihtavuori N540 | <<locked>> | 90% | 55,912 psi | 88% | 3294 fps | 100% |
| Vihtavuori N550 | <<locked>> | 98% | 54,766 psi | 86% | 3356 fps | 98.6% |
| Vihtavuori N555ᴾ | <<locked>> | 100% | 43,410 psi | 68% | 3202 fps | 97.3% |
| Winchester 6.5 StaBALL | <<locked>> | 98% | 56,202 psi | 88% | 3327 fps | 99.9% |
| Winchester 748 | <<locked>> | 86% | 57,537 psi | 90% | 3389 fps | 100% |
| Winchester 760 | <<locked>> | 98% | 57,319 psi | 90% | 3428 fps | 97% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 35,621 psi | 56% | 3084 fps | 96.5% |
| Winchester StaBALL Match | <<locked>> | 88% | 56,492 psi | 89% | 3363 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% | 48,588 psi | 76% | 3123 fps | 100% |
| Accurate 2460 | <<locked>> | 80% | 53,519 psi | 84% | 3248 fps | 100% |
| Accurate 2495 | <<locked>> | 80% | 41,278 psi | 65% | 3022 fps | 100% |
| Accurate 2520 | <<locked>> | 80% | 48,588 psi | 76% | 3196 fps | 100% |
| Accurate 2700 | <<locked>> | 88% | 53,345 psi | 84% | 3225 fps | 95.1% |
| Accurate 4064 | <<locked>> | 80% | 39,015 psi | 61% | 3005 fps | 99.6% |
| Accurate 4350 | <<locked>> | 90% | 40,712 psi | 64% | 3097 fps | 95.7% |
| ADI AR 2206H | <<locked>> | 80% | 44,715 psi | 70% | 3136 fps | 98% |
| ADI AR 2208 | <<locked>> | 80% | 38,072 psi | 60% | 2959 fps | 95.4% |
| ADI Benchmark 8208 | <<locked>> | 80% | 46,746 psi | 73% | 3153 fps | 99.2% |
| Alliant AR-Comp | <<locked>> | 80% | 46,978 psi | 74% | 3150 fps | 100% |
| Alliant Power Pro 2000-MR | 45.5 gr | 80% | 40,741 psi | 64% | 3150 fps | 96% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 37,608 psi | 59% | 2979 fps | 97.1% |
| Alliant Reloder-15 | <<locked>> | 80% | 40,393 psi | 63% | 3051 fps | 96.3% |
| Alliant Reloder-16 | <<locked>> | 90% | 40,132 psi | 63% | 3104 fps | 95.6% |
| Alliant Reloder-17 | 45.9 gr | 82% | 34,882 psi | 55% | 2989 fps | 95.4% |
| Alliant Reloder-23 | <<locked>> | 96% | 34,896 psi | 55% | 2979 fps | 95.4% |
| Alliant Reloder-26 | <<locked>> | 98% | 41,466 psi | 65% | 3209 fps | 95.3% |
| Baschieri & Pellagri 107 | <<locked>> | 80% | 44,193 psi | 69% | 3133 fps | 96.9% |
| Bofors RP3 | <<locked>> | 80% | 37,391 psi | 59% | 2982 fps | 97.1% |
| Bofors RP7 | <<locked>> | 94% | 52,881 psi | 83% | 3258 fps | 95.2% |
| Hodgdon Benchmark | <<locked>> | 80% | 48,588 psi | 76% | 3146 fps | 99.7% |
| Hodgdon BL-C2 | <<locked>> | 80% | 45,861 psi | 72% | 3169 fps | 99.5% |
| Hodgdon CFE223 | <<locked>> | 80% | 50,734 psi | 80% | 3337 fps | 98.7% |
| Hodgdon H322 | <<locked>> | 80% | 53,635 psi | 84% | 3278 fps | 100% |
| Hodgdon H380 | <<locked>> | 82% | 41,060 psi | 64% | 3051 fps | 95.2% |
| Hodgdon H414 | <<locked>> | 94% | 49,676 psi | 78% | 3287 fps | 95.2% |
| Hodgdon H4895 | <<locked>> | 80% | 45,107 psi | 71% | 3150 fps | 98.5% |
| Hodgdon Hybrid 100V | <<locked>> | 88% | 34,766 psi | 54% | 2923 fps | 95.5% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 41,162 psi | 65% | 3104 fps | 98.1% |
| Hodgdon TrailBoss | <<locked>> | 80% | 26,252 psi | 41% | 1890 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 43,352 psi | 68% | 3097 fps | 98.2% |
| IMR 3031 | <<locked>> | 80% | 44,788 psi | 70% | 3156 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 39,958 psi | 63% | 3002 fps | 96.4% |
| IMR 4166 Enduron | <<locked>> | 86% | 51,488 psi | 81% | 3212 fps | 95.6% |
| IMR 4198 | <<locked>> | 80% | 54,157 psi | 85% | 3196 fps | 100% |
| IMR 4350 | <<locked>> | 98% | 53,301 psi | 84% | 3284 fps | 95.4% |
| IMR 4451 Enduron | <<locked>> | 92% | 51,532 psi | 81% | 3238 fps | 95.5% |
| IMR 4831 | <<locked>> | 90% | 39,175 psi | 61% | 3041 fps | 95.3% |
| IMR 4895 | <<locked>> | 80% | 41,394 psi | 65% | 3091 fps | 97.3% |
| IMR 8208 XBR | <<locked>> | 80% | 46,746 psi | 73% | 3153 fps | 99.2% |
| Lovex D073.5 | <<locked>> | 80% | 53,156 psi | 83% | 3251 fps | 100% |
| Lovex D073.6 | <<locked>> | 80% | 43,932 psi | 69% | 3114 fps | 99.7% |
| Lovex S060 | <<locked>> | 80% | 44,831 psi | 70% | 3071 fps | 98.1% |
| Lovex S062 | <<locked>> | 80% | 39,943 psi | 63% | 3009 fps | 98.1% |
| Lovex S065 | <<locked>> | 90% | 44,817 psi | 70% | 3107 fps | 95.4% |
| Lovex S070 | <<locked>> | 94% | 48,631 psi | 76% | 3202 fps | 95.1% |
| Norma 201 | <<locked>> | 80% | 43,816 psi | 69% | 3087 fps | 98.9% |
| Norma 202 | <<locked>> | 80% | 44,048 psi | 69% | 3100 fps | 99.9% |
| Norma 203B | <<locked>> | 80% | 39,784 psi | 62% | 3038 fps | 96.8% |
| Norma URP | <<locked>> | 90% | 40,741 psi | 64% | 3097 fps | 95.6% |
| Ramshot Big Game | <<locked>> | 80% | 39,465 psi | 62% | 3048 fps | 96.5% |
| Ramshot Hunter | <<locked>> | 94% | 45,368 psi | 71% | 3202 fps | 95% |
| Ramshot TAC | <<locked>> | 80% | 46,978 psi | 74% | 3150 fps | 96.2% |
| Ramshot Wild Boar | <<locked>> | 80% | 46,572 psi | 73% | 3176 fps | 98.3% |
| Ramshot X-Terminator | <<locked>> | 80% | 50,618 psi | 79% | 3205 fps | 98.9% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 26,614 psi | 42% | 1936 fps | 100% |
| ReloadSwiss RS 40 | <<locked>> | 80% | 52,620 psi | 82% | 3258 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 86% | 47,282 psi | 74% | 3159 fps | 95.2% |
| ReloadSwiss RS 52 | <<locked>> | 80% | 42,540 psi | 67% | 3169 fps | 96.9% |
| ReloadSwiss RS 60 | 44.8 gr | 80% | 34,693 psi | 54% | 2999 fps | 97.9% |
| ReloadSwiss RS 62 | <<locked>> | 90% | 40,524 psi | 64% | 3114 fps | 95.2% |
| ReloadSwiss RS 70 | <<locked>> | 92% | 43,294 psi | 68% | 3189 fps | 95.4% |
| Rottweil R 901 | <<locked>> | 80% | 47,776 psi | 75% | 3146 fps | 100% |
| Rottweil R 902 | <<locked>> | 80% | 41,698 psi | 65% | 3028 fps | 98.4% |
| Rottweil R 903 | <<locked>> | 80% | 35,186 psi | 55% | 2917 fps | 96% |
| Rottweil R 907 | <<locked>> | 94% | 52,881 psi | 83% | 3258 fps | 95.2% |
| Shooters World Long Rifle | <<locked>> | 90% | 44,817 psi | 70% | 3107 fps | 95.4% |
| Shooters World Match Rifle | <<locked>> | 80% | 43,932 psi | 69% | 3114 fps | 99.7% |
| Shooters World Precision | <<locked>> | 80% | 39,943 psi | 63% | 3009 fps | 98.1% |
| Shooters World SW4350 | <<locked>> | 94% | 48,631 psi | 76% | 3202 fps | 95.1% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 36,100 psi | 57% | 2966 fps | 95.3% |
| SNPE Vectan SP 7 | <<locked>> | 80% | 45,121 psi | 71% | 3114 fps | 96.2% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 43,265 psi | 68% | 3097 fps | 97.7% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 45,078 psi | 71% | 3045 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 37,536 psi | 59% | 2884 fps | 99.8% |
| SNPE Vectan Tubal 7000 | <<locked>> | 94% | 50,937 psi | 80% | 3173 fps | 95.5% |
| Somchem S321 | <<locked>> | 80% | 50,981 psi | 80% | 3245 fps | 99.8% |
| Somchem S335 | <<locked>> | 80% | 44,802 psi | 70% | 3045 fps | 100% |
| Somchem S341 | <<locked>> | 80% | 45,005 psi | 71% | 3117 fps | 98% |
| Somchem S355 | <<locked>> | 80% | 35,940 psi | 56% | 2927 fps | 96.1% |
| Somchem S365 | <<locked>> | 86% | 31,836 psi | 50% | 2900 fps | 95.9% |
| Vihtavuori N130 | <<locked>> | 80% | 50,865 psi | 80% | 3123 fps | 100% |
| Vihtavuori N133 | <<locked>> | 80% | 45,411 psi | 71% | 3041 fps | 100% |
| Vihtavuori N135 | <<locked>> | 80% | 41,089 psi | 64% | 3018 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 41,901 psi | 66% | 3025 fps | 99.9% |
| Vihtavuori N150 | <<locked>> | 80% | 34,287 psi | 54% | 2858 fps | 97% |
| Vihtavuori N160 | <<locked>> | 88% | 39,740 psi | 62% | 3035 fps | 95.2% |
| Vihtavuori N530 | <<locked>> | 80% | 47,007 psi | 74% | 3150 fps | 99.3% |
| Vihtavuori N540 | <<locked>> | 80% | 40,495 psi | 63% | 3005 fps | 99.6% |
| Vihtavuori N550 | <<locked>> | 90% | 41,872 psi | 66% | 3094 fps | 95.6% |
| Vihtavuori N555 | <<locked>> | 96% | 37,840 psi | 59% | 3071 fps | 95.5% |
| Winchester 6.5 StaBALL | <<locked>> | 84% | 34,911 psi | 55% | 2881 fps | 95.8% |
| Winchester 748 | <<locked>> | 80% | 46,644 psi | 73% | 3196 fps | 99.7% |
| Winchester 760 | <<locked>> | 94% | 50,024 psi | 78% | 3294 fps | 95.3% |
| Winchester StaBALL HD | <<locked>> | 98% | 33,315 psi | 52% | 3002 fps | 95% |
| Winchester StaBALL Match | <<locked>> | 80% | 43,018 psi | 67% | 3104 fps | 98.2% |
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 109 powders for .255 GS loaded with the .257 | 87gr | Frontier PH HPFB. ReloadSwiss RS 60 delivers the highest muzzle velocity at 3,488 fps; across all powders the maximum-charge window runs from 2,106 fps to 3,488 fps. Accurate 3100 gives the best case fill at 100 %, and 109 of the 109 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 87.0 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-16 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 | 87gr | Frontier PH HPFB they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Accurate 3100, ADI AR 2209, Alliant Reloder-19 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.