Load Specifications
Load data in caliber .300 Weath. Mag. with .308 | 135gr | Atomic 29 FNHP 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.
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 2495 | <<locked>> | 84% | 54,433 psi | 85% | 3163 fps | 100% |
| Accurate 2700 | <<locked>> | 86% | 56,869 psi | 89% | 3232 fps | 97.5% |
| Accurate 3100ᴾ | <<locked>> | 100% | 50,256 psi | 79% | 3182 fps | 97.9% |
| Accurate 4064 | <<locked>> | 86% | 54,940 psi | 86% | 3219 fps | 100% |
| Accurate 4350 | <<locked>> | 94% | 56,275 psi | 88% | 3323 fps | 99.7% |
| ADI AR 2206H | <<locked>> | 82% | 54,607 psi | 86% | 3255 fps | 99.9% |
| ADI AR 2208 | <<locked>> | 88% | 55,927 psi | 88% | 3258 fps | 99.8% |
| ADI AR 2209 | <<locked>> | 98% | 53,969 psi | 85% | 3294 fps | 96.1% |
| ADI Benchmark 8208 | <<locked>> | 82% | 56,884 psi | 89% | 3258 fps | 100% |
| Alliant Power Pro 2000-MR | <<locked>> | 84% | 55,216 psi | 87% | 3386 fps | 99.9% |
| Alliant Power Pro Varmint | <<locked>> | 98% | 54,056 psi | 85% | 3294 fps | 96.2% |
| Alliant Reloder- TS 15.5 | <<locked>> | 88% | 56,507 psi | 89% | 3281 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 86% | 56,782 psi | 89% | 3307 fps | 99.9% |
| Alliant Reloder-16 | <<locked>> | 96% | 57,043 psi | 89% | 3389 fps | 99.9% |
| Alliant Reloder-17 | <<locked>> | 90% | 54,824 psi | 86% | 3360 fps | 100% |
| Alliant Reloder-19ᴾ | <<locked>> | 100% | 56,927 psi | 89% | 3346 fps | 96.8% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 47,253 psi | 74% | 3205 fps | 99.8% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 41,220 psi | 65% | 3087 fps | 96.3% |
| Alliant Reloder-26ᴾ | <<locked>> | 100% | 54,723 psi | 86% | 3419 fps | 99.7% |
| Baschieri & Pellagri 107 | <<locked>> | 82% | 54,679 psi | 86% | 3264 fps | 99.7% |
| Bofors RP3 | <<locked>> | 88% | 57,290 psi | 90% | 3297 fps | 100% |
| Bofors RP7 | <<locked>> | 92% | 56,942 psi | 89% | 3271 fps | 97.7% |
| Hodgdon BL-C2 | <<locked>> | 82% | 57,043 psi | 89% | 3287 fps | 100% |
| Hodgdon H380 | <<locked>> | 86% | 54,244 psi | 85% | 3251 fps | 99.3% |
| Hodgdon H414 | <<locked>> | 92% | 55,027 psi | 86% | 3314 fps | 98% |
| Hodgdon H4350 | <<locked>> | 90% | 54,984 psi | 86% | 3274 fps | 96.7% |
| Hodgdon H4895 | <<locked>> | 82% | 55,201 psi | 87% | 3268 fps | 100% |
| Hodgdon Hybrid 100V | <<locked>> | 98% | 57,522 psi | 90% | 3310 fps | 100% |
| Hodgdon LEVERevolution | <<locked>> | 84% | 55,535 psi | 87% | 3301 fps | 100% |
| Hodgdon Superformance | <<locked>> | 92% | 55,608 psi | 87% | 3350 fps | 97.8% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 35,810 psi | 56% | 2087 fps | 100% |
| Hodgdon VARGET | <<locked>> | 84% | 56,521 psi | 89% | 3268 fps | 100% |
| IMR 3031 | <<locked>> | 82% | 55,608 psi | 87% | 3248 fps | 100% |
| IMR 4064 | <<locked>> | 86% | 55,405 psi | 87% | 3241 fps | 99.9% |
| IMR 4166 Enduron | <<locked>> | 84% | 54,665 psi | 86% | 3212 fps | 97.8% |
| IMR 4350 | <<locked>> | 94% | 54,389 psi | 85% | 3241 fps | 97.3% |
| IMR 4451 Enduron | <<locked>> | 90% | 55,216 psi | 87% | 3245 fps | 97.8% |
| IMR 4831 | <<locked>> | 96% | 56,637 psi | 89% | 3314 fps | 99.8% |
| IMR 4895 | <<locked>> | 84% | 54,592 psi | 86% | 3281 fps | 100% |
| IMR 8208 XBR | <<locked>> | 82% | 56,884 psi | 89% | 3258 fps | 100% |
| Lovex D073.6 | <<locked>> | 82% | 54,708 psi | 86% | 3222 fps | 100% |
| Lovex S060 | <<locked>> | 84% | 57,159 psi | 90% | 3235 fps | 100% |
| Lovex S062 | <<locked>> | 86% | 55,274 psi | 87% | 3235 fps | 100% |
| Lovex S065 | <<locked>> | 92% | 54,940 psi | 86% | 3238 fps | 98.9% |
| Lovex S070 | <<locked>> | 94% | 56,362 psi | 88% | 3281 fps | 98.3% |
| Norma 201 | <<locked>> | 84% | 56,565 psi | 89% | 3248 fps | 100% |
| Norma 202 | <<locked>> | 84% | 57,450 psi | 90% | 3248 fps | 100% |
| Norma 203B | <<locked>> | 86% | 56,014 psi | 88% | 3291 fps | 100% |
| Norma 204 | <<locked>> | 94% | 55,303 psi | 87% | 3294 fps | 96.2% |
| Norma MRPᴾ | <<locked>> | 100% | 53,563 psi | 84% | 3363 fps | 97.7% |
| Norma URP | <<locked>> | 94% | 55,056 psi | 86% | 3307 fps | 99.6% |
| Ramshot Big Game | <<locked>> | 86% | 57,174 psi | 90% | 3317 fps | 100% |
| Ramshot Hunter | <<locked>> | 94% | 54,027 psi | 85% | 3297 fps | 98.5% |
| Ramshot TAC | <<locked>> | 82% | 57,232 psi | 90% | 3274 fps | 99.3% |
| Ramshot Wild Boar | <<locked>> | 82% | 57,305 psi | 90% | 3294 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 36,448 psi | 57% | 2136 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 86% | 54,433 psi | 85% | 3232 fps | 98.3% |
| ReloadSwiss RS 52 | <<locked>> | 82% | 54,041 psi | 85% | 3317 fps | 99.7% |
| ReloadSwiss RS 60 | <<locked>> | 88% | 54,273 psi | 85% | 3356 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 94% | 56,304 psi | 88% | 3343 fps | 99.6% |
| ReloadSwiss RS 70 | <<locked>> | 94% | 55,158 psi | 86% | 3376 fps | 99.5% |
| Rottweil R 901 | <<locked>> | 82% | 57,159 psi | 90% | 3232 fps | 100% |
| Rottweil R 902 | <<locked>> | 86% | 57,348 psi | 90% | 3251 fps | 100% |
| Rottweil R 903 | <<locked>> | 90% | 57,334 psi | 90% | 3294 fps | 100% |
| Rottweil R 905ᴾ | <<locked>> | 100% | 56,130 psi | 88% | 3333 fps | 96.8% |
| Rottweil R 907 | <<locked>> | 92% | 56,942 psi | 89% | 3271 fps | 97.7% |
| Shooters World Long Rifle | <<locked>> | 92% | 54,940 psi | 86% | 3238 fps | 98.9% |
| Shooters World Match Rifle | <<locked>> | 82% | 54,708 psi | 86% | 3222 fps | 100% |
| Shooters World Precision | <<locked>> | 86% | 55,274 psi | 87% | 3235 fps | 100% |
| Shooters World SW4350 | <<locked>> | 94% | 56,362 psi | 88% | 3281 fps | 98.3% |
| SNPE Vectan SP 11 | <<locked>> | 88% | 55,695 psi | 87% | 3301 fps | 100% |
| SNPE Vectan SP 7 | <<locked>> | 82% | 55,898 psi | 88% | 3251 fps | 99.4% |
| SNPE Vectan SP 9 | <<locked>> | 84% | 56,884 psi | 89% | 3281 fps | 100% |
| SNPE Vectan Tubal 3000 | <<locked>> | 84% | 57,740 psi | 90% | 3182 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 88% | 55,143 psi | 86% | 3130 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 92% | 54,940 psi | 86% | 3186 fps | 97.9% |
| SNPE Vectan Tubal 8000ᴾ | <<locked>> | 100% | 55,622 psi | 87% | 3327 fps | 96.7% |
| Somchem S335 | <<locked>> | 84% | 57,217 psi | 90% | 3176 fps | 100% |
| Somchem S341 | <<locked>> | 82% | 55,608 psi | 87% | 3238 fps | 100% |
| Somchem S355 | <<locked>> | 90% | 57,392 psi | 90% | 3287 fps | 100% |
| Somchem S365 | <<locked>> | 96% | 53,998 psi | 85% | 3310 fps | 100% |
| Somchem S385ᴾ | <<locked>> | 100% | 56,637 psi | 89% | 3304 fps | 97.7% |
| Vihtavuori N133 | <<locked>> | 82% | 54,752 psi | 86% | 3117 fps | 100% |
| Vihtavuori N135 | <<locked>> | 86% | 57,537 psi | 90% | 3209 fps | 100% |
| Vihtavuori N140 | <<locked>> | 84% | 54,578 psi | 86% | 3173 fps | 100% |
| Vihtavuori N150 | <<locked>> | 90% | 55,288 psi | 87% | 3209 fps | 100% |
| Vihtavuori N160 | <<locked>> | 94% | 57,450 psi | 90% | 3307 fps | 99.7% |
| Vihtavuori N530 | <<locked>> | 82% | 57,479 psi | 90% | 3258 fps | 100% |
| Vihtavuori N540 | <<locked>> | 86% | 56,449 psi | 88% | 3219 fps | 100% |
| Vihtavuori N550 | <<locked>> | 94% | 56,463 psi | 88% | 3307 fps | 99.6% |
| Vihtavuori N555ᴾ | <<locked>> | 100% | 52,837 psi | 83% | 3297 fps | 99.7% |
| Winchester 6.5 StaBALL | <<locked>> | 94% | 57,667 psi | 90% | 3274 fps | 100% |
| Winchester 760 | <<locked>> | 92% | 55,230 psi | 87% | 3320 fps | 98% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 42,699 psi | 67% | 3238 fps | 100% |
| Winchester StaBALL Match | <<locked>> | 84% | 56,985 psi | 89% | 3287 fps | 100% |
| Winchester Supreme 780ᴾ | <<locked>> | 100% | 53,476 psi | 84% | 3232 fps | 96% |
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 2495 | <<locked>> | 80% | 47,674 psi | 75% | 3054 fps | 100% |
| Accurate 2700 | <<locked>> | 80% | 46,514 psi | 73% | 3035 fps | 95.1% |
| Accurate 3100 | <<locked>> | 94% | 40,596 psi | 64% | 2982 fps | 95.3% |
| Accurate 4064 | <<locked>> | 80% | 45,121 psi | 71% | 3048 fps | 100% |
| Accurate 4350 | <<locked>> | 82% | 36,506 psi | 57% | 2910 fps | 95.7% |
| ADI AR 2206H | <<locked>> | 80% | 51,184 psi | 80% | 3192 fps | 99.8% |
| ADI AR 2208 | <<locked>> | 80% | 43,424 psi | 68% | 3015 fps | 98.3% |
| ADI AR 2209 | <<locked>> | 96% | 50,459 psi | 79% | 3228 fps | 95.1% |
| ADI Benchmark 8208 | <<locked>> | 80% | 53,301 psi | 84% | 3199 fps | 100% |
| Alliant Power Pro 2000-MR | <<locked>> | 80% | 47,601 psi | 75% | 3241 fps | 99.1% |
| Alliant Power Pro Varmint | <<locked>> | 96% | 50,546 psi | 79% | 3225 fps | 95.3% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 43,569 psi | 68% | 3041 fps | 99.4% |
| Alliant Reloder-15 | <<locked>> | 80% | 46,659 psi | 73% | 3117 fps | 99% |
| Alliant Reloder-16 | <<locked>> | 82% | 36,056 psi | 56% | 2930 fps | 95.8% |
| Alliant Reloder-17 | 71.8 gr | 80% | 38,101 psi | 60% | 3009 fps | 98.2% |
| Alliant Reloder-19 | <<locked>> | 96% | 49,864 psi | 78% | 3215 fps | 95.2% |
| Alliant Reloder-23 | <<locked>> | 88% | 31,662 psi | 50% | 2818 fps | 95.7% |
| Alliant Reloder-25 | <<locked>> | 98% | 38,595 psi | 60% | 3018 fps | 95.1% |
| Alliant Reloder-26 | <<locked>> | 90% | 37,289 psi | 58% | 3028 fps | 95.5% |
| Baschieri & Pellagri 107 | <<locked>> | 80% | 51,082 psi | 80% | 3199 fps | 99.3% |
| Bofors RP3 | <<locked>> | 80% | 43,526 psi | 68% | 3045 fps | 99.4% |
| Bofors RP7 | <<locked>> | 86% | 47,021 psi | 74% | 3081 fps | 95.5% |
| Hodgdon BL-C2 | <<locked>> | 80% | 53,055 psi | 83% | 3222 fps | 100% |
| Hodgdon H380 | <<locked>> | 80% | 44,237 psi | 69% | 3054 fps | 97.6% |
| Hodgdon H414 | <<locked>> | 86% | 44,686 psi | 70% | 3110 fps | 95.5% |
| Hodgdon H4350 | <<locked>> | 86% | 48,124 psi | 75% | 3143 fps | 95% |
| Hodgdon H4895 | <<locked>> | 80% | 51,721 psi | 81% | 3205 fps | 99.9% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 30,980 psi | 49% | 2743 fps | 95.5% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 48,240 psi | 76% | 3173 fps | 99.9% |
| Hodgdon Superformance | <<locked>> | 88% | 47,776 psi | 75% | 3199 fps | 96% |
| Hodgdon TrailBoss | <<locked>> | 80% | 26,731 psi | 42% | 1870 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 49,588 psi | 78% | 3146 fps | 99.8% |
| IMR 3031 | <<locked>> | 80% | 52,083 psi | 82% | 3192 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 45,629 psi | 72% | 3058 fps | 98.9% |
| IMR 4166 Enduron | <<locked>> | 80% | 48,109 psi | 75% | 3087 fps | 96.4% |
| IMR 4350 | <<locked>> | 90% | 47,819 psi | 75% | 3117 fps | 95.8% |
| IMR 4451 Enduron | <<locked>> | 84% | 45,600 psi | 71% | 3054 fps | 95.6% |
| IMR 4831 | <<locked>> | 82% | 35,157 psi | 55% | 2861 fps | 95.3% |
| IMR 4895 | <<locked>> | 80% | 47,877 psi | 75% | 3153 fps | 99.5% |
| IMR 8208 XBR | <<locked>> | 80% | 53,301 psi | 84% | 3199 fps | 100% |
| Lovex D073.6 | <<locked>> | 80% | 51,155 psi | 80% | 3163 fps | 100% |
| Lovex S060 | <<locked>> | 80% | 50,314 psi | 79% | 3117 fps | 99.7% |
| Lovex S062 | <<locked>> | 80% | 45,585 psi | 71% | 3058 fps | 99.8% |
| Lovex S065 | <<locked>> | 82% | 40,045 psi | 63% | 2933 fps | 95.5% |
| Lovex S070 | <<locked>> | 86% | 43,439 psi | 68% | 3025 fps | 95.4% |
| Norma 201 | <<locked>> | 80% | 49,821 psi | 78% | 3130 fps | 100% |
| Norma 202 | <<locked>> | 80% | 50,604 psi | 79% | 3140 fps | 100% |
| Norma 203B | <<locked>> | 80% | 46,035 psi | 72% | 3104 fps | 99.2% |
| Norma 204 | <<locked>> | 92% | 51,517 psi | 81% | 3225 fps | 95.3% |
| Norma MRP | <<locked>> | 96% | 46,456 psi | 73% | 3219 fps | 95.9% |
| Norma URP | <<locked>> | 82% | 36,564 psi | 57% | 2913 fps | 95.6% |
| Ramshot Big Game | <<locked>> | 80% | 46,238 psi | 72% | 3117 fps | 99.2% |
| Ramshot Hunter | <<locked>> | 86% | 40,915 psi | 64% | 3028 fps | 95.3% |
| Ramshot TAC | <<locked>> | 80% | 53,388 psi | 84% | 3209 fps | 98.8% |
| Ramshot Wild Boar | <<locked>> | 80% | 53,548 psi | 84% | 3232 fps | 99.9% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 27,050 psi | 42% | 1913 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 44,353 psi | 70% | 3031 fps | 96.1% |
| ReloadSwiss RS 52 | <<locked>> | 80% | 50,256 psi | 79% | 3248 fps | 99.4% |
| ReloadSwiss RS 60 | 71.8 gr | 80% | 40,582 psi | 64% | 3084 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 82% | 36,535 psi | 57% | 2930 fps | 95.3% |
| ReloadSwiss RS 70 | 76.6 gr | 84% | 38,508 psi | 60% | 3009 fps | 95.5% |
| Rottweil R 901 | <<locked>> | 80% | 53,795 psi | 84% | 3176 fps | 100% |
| Rottweil R 902 | <<locked>> | 80% | 47,326 psi | 74% | 3077 fps | 99.9% |
| Rottweil R 903 | <<locked>> | 80% | 40,814 psi | 64% | 2979 fps | 98.8% |
| Rottweil R 905 | <<locked>> | 96% | 48,878 psi | 77% | 3196 fps | 95% |
| Rottweil R 907 | <<locked>> | 86% | 47,021 psi | 74% | 3081 fps | 95.5% |
| Shooters World Long Rifle | <<locked>> | 82% | 40,045 psi | 63% | 2933 fps | 95.5% |
| Shooters World Match Rifle | <<locked>> | 80% | 51,155 psi | 80% | 3163 fps | 100% |
| Shooters World Precision | <<locked>> | 80% | 45,585 psi | 71% | 3058 fps | 99.8% |
| Shooters World SW4350 | <<locked>> | 86% | 43,439 psi | 68% | 3025 fps | 95.4% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 42,235 psi | 66% | 3041 fps | 98.5% |
| SNPE Vectan SP 7 | <<locked>> | 80% | 52,170 psi | 82% | 3186 fps | 99% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 49,705 psi | 78% | 3153 fps | 99.6% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 50,937 psi | 80% | 3077 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 42,815 psi | 67% | 2917 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 86% | 45,020 psi | 71% | 2995 fps | 95.7% |
| SNPE Vectan Tubal 8000 | <<locked>> | 98% | 51,895 psi | 81% | 3258 fps | 95.8% |
| Somchem S335 | <<locked>> | 80% | 50,589 psi | 79% | 3071 fps | 100% |
| Somchem S341 | <<locked>> | 80% | 51,953 psi | 81% | 3179 fps | 99.8% |
| Somchem S355 | <<locked>> | 80% | 41,437 psi | 65% | 2986 fps | 98.8% |
| Somchem S365 | <<locked>> | 80% | 30,560 psi | 48% | 2785 fps | 96.9% |
| Somchem S385 | <<locked>> | 94% | 46,137 psi | 72% | 3104 fps | 95.3% |
| Vihtavuori N133 | <<locked>> | 80% | 51,474 psi | 81% | 3064 fps | 100% |
| Vihtavuori N135 | <<locked>> | 80% | 47,514 psi | 74% | 3051 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 47,863 psi | 75% | 3058 fps | 100% |
| Vihtavuori N150 | <<locked>> | 80% | 39,508 psi | 62% | 2910 fps | 99.4% |
| Vihtavuori N160 | <<locked>> | 80% | 35,578 psi | 56% | 2858 fps | 95.2% |
| Vihtavuori N530 | <<locked>> | 80% | 53,606 psi | 84% | 3196 fps | 100% |
| Vihtavuori N540 | <<locked>> | 80% | 46,369 psi | 73% | 3045 fps | 100% |
| Vihtavuori N550 | <<locked>> | 82% | 37,565 psi | 59% | 2917 fps | 95.8% |
| Vihtavuori N555 | <<locked>> | 88% | 34,998 psi | 55% | 2907 fps | 95.8% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 35,099 psi | 55% | 2828 fps | 97.6% |
| Winchester 760 | <<locked>> | 86% | 44,860 psi | 70% | 3114 fps | 95.6% |
| Winchester StaBALL HD | <<locked>> | 90% | 30,081 psi | 47% | 2844 fps | 95.5% |
| Winchester StaBALL Match | <<locked>> | 80% | 49,632 psi | 78% | 3159 fps | 99.8% |
| Winchester Supreme 780 | <<locked>> | 98% | 49,617 psi | 78% | 3159 fps | 95% |
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 .300 Weath. Mag. loaded with the .308 | 135gr | Atomic 29 FNHP. Alliant Reloder-26 delivers the highest muzzle velocity at 3,419 fps; across all powders the maximum-charge window runs from 2,087 fps to 3,419 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 135.0 gr projectile in 0.308" calls for a 1:15.5 twist; slower twists will usually not stabilise this weight. Accurate 3100, Alliant Reloder-19, 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. ReloadSwiss RS 70, Alliant Reloder-17, ReloadSwiss RS 60 rank at the top here: for .300 Weath. Mag. with the .308 | 135gr | Atomic 29 FNHP 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.