Load Specifications
Load data in caliber .30-378 Weath. Mag. with .308 | 165gr | Speer Grand Slam bullet and 50 powders. The key underlying parameters are shown in the table above.
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: 26"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 3100 | <<locked>> | 86% | 55,521 psi | 87% | 3136 fps | 100% |
| Accurate High Country | <<locked>> | 84% | 57,421 psi | 90% | 3304 fps | 99.8% |
| Accurate MAGPRO | <<locked>> | 84% | 54,505 psi | 85% | 3245 fps | 99% |
| ADI AR 2209 | <<locked>> | 84% | 56,405 psi | 88% | 3228 fps | 100% |
| ADI AR 2213 | <<locked>> | 86% | 55,158 psi | 86% | 3241 fps | 99.6% |
| ADI AR 2217 | <<locked>> | 94% | 54,259 psi | 85% | 3222 fps | 99.8% |
| ADI AR 2218 | <<locked>> | 98% | 54,766 psi | 86% | 3337 fps | 98% |
| ADI AR 2225 | <<locked>> | 98% | 57,377 psi | 90% | 3304 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 84% | 56,130 psi | 88% | 3219 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 86% | 55,709 psi | 87% | 3238 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 88% | 57,580 psi | 90% | 3199 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 90% | 54,447 psi | 85% | 3219 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 82% | 54,404 psi | 85% | 3228 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 96% | 56,739 psi | 89% | 3317 fps | 98.1% |
| Alliant Reloder-50ᴾ | <<locked>> | 100% | 56,594 psi | 89% | 3301 fps | 97.7% |
| Baschieri & Pellagri 109 | <<locked>> | 88% | 55,579 psi | 87% | 3196 fps | 98.1% |
| Bofors RP15 | <<locked>> | 88% | 55,085 psi | 86% | 3225 fps | 99.9% |
| Bofors RP30 | <<locked>> | 92% | 54,157 psi | 85% | 3232 fps | 99.8% |
| Bofors RP5 | <<locked>> | 86% | 55,709 psi | 87% | 3238 fps | 100% |
| Hodgdon H1000 | <<locked>> | 92% | 55,637 psi | 87% | 3241 fps | 100% |
| Hodgdon H4831 | <<locked>> | 84% | 54,085 psi | 85% | 3169 fps | 99.2% |
| Hodgdon H4831 SC | <<locked>> | 86% | 56,826 psi | 89% | 3215 fps | 99.5% |
| Hodgdon Hybrid 100V | <<locked>> | 82% | 56,768 psi | 89% | 3130 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 92% | 57,537 psi | 90% | 3376 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,753 psi | 59% | 2096 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 84% | 54,360 psi | 85% | 3146 fps | 99.3% |
| IMR 7828 SSC | <<locked>> | 88% | 57,421 psi | 90% | 3291 fps | 99.8% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 56,289 psi | 88% | 3281 fps | 99.9% |
| Lovex S071 | <<locked>> | 92% | 57,305 psi | 90% | 3163 fps | 100% |
| Norma 217ᴾ | <<locked>> | 100% | 57,624 psi | 90% | 3304 fps | 100% |
| Norma MRP | <<locked>> | 84% | 55,782 psi | 87% | 3255 fps | 100% |
| Ramshot Grand | <<locked>> | 86% | 54,897 psi | 86% | 3248 fps | 99.8% |
| Ramshot Magnum | <<locked>> | 90% | 57,566 psi | 90% | 3235 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,798 psi | 61% | 2146 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 90% | 54,476 psi | 85% | 3294 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 92% | 53,795 psi | 84% | 3251 fps | 99.1% |
| Rottweil R 904 | <<locked>> | 84% | 56,869 psi | 89% | 3196 fps | 99.7% |
| Rottweil R 905 | <<locked>> | 84% | 55,854 psi | 88% | 3209 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 84% | 55,463 psi | 87% | 3202 fps | 100% |
| Somchem S361 | <<locked>> | 82% | 54,592 psi | 86% | 3120 fps | 99.2% |
| Somchem S385 | <<locked>> | 84% | 56,188 psi | 88% | 3176 fps | 100% |
| Vihtavuori N165 | <<locked>> | 88% | 56,289 psi | 88% | 3159 fps | 100% |
| Vihtavuori N170 | <<locked>> | 92% | 55,695 psi | 87% | 3179 fps | 96.4% |
| Vihtavuori N555 | <<locked>> | 84% | 55,666 psi | 87% | 3176 fps | 100% |
| Vihtavuori N560 | <<locked>> | 84% | 55,143 psi | 86% | 3255 fps | 99.4% |
| Vihtavuori N565 | <<locked>> | 90% | 56,463 psi | 88% | 3248 fps | 99.6% |
| Vihtavuori N568 | <<locked>> | 92% | 54,157 psi | 85% | 3255 fps | 98.8% |
| Vihtavuori N570 | <<locked>> | 94% | 55,637 psi | 87% | 3320 fps | 97.5% |
| Winchester StaBALL HD | <<locked>> | 86% | 54,085 psi | 85% | 3235 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 86% | 56,159 psi | 88% | 3173 fps | 100% |
Start Load - Barrel Length: 26"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 3100 | <<locked>> | 80% | 45,237 psi | 71% | 2956 fps | 100% |
| Accurate High Country | <<locked>> | 80% | 49,937 psi | 78% | 3166 fps | 99.1% |
| Accurate MAGPRO | <<locked>> | 80% | 47,253 psi | 74% | 3100 fps | 97.6% |
| ADI AR 2209 | <<locked>> | 80% | 49,284 psi | 77% | 3100 fps | 99.5% |
| ADI AR 2213 | <<locked>> | 80% | 44,527 psi | 70% | 3035 fps | 98% |
| ADI AR 2217 | <<locked>> | 82% | 35,592 psi | 56% | 2812 fps | 95.5% |
| ADI AR 2218 | <<locked>> | 94% | 47,239 psi | 74% | 3173 fps | 95.8% |
| ADI AR 2225 | <<locked>> | 80% | 30,574 psi | 48% | 2707 fps | 96.4% |
| Alliant Reloder-19 | <<locked>> | 80% | 49,139 psi | 77% | 3091 fps | 99.5% |
| Alliant Reloder-22 | <<locked>> | 80% | 45,310 psi | 71% | 3041 fps | 99% |
| Alliant Reloder-23 | <<locked>> | 80% | 44,077 psi | 69% | 2976 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 38,276 psi | 60% | 2907 fps | 99.8% |
| Alliant Reloder-26 | <<locked>> | 80% | 50,473 psi | 79% | 3163 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 90% | 45,223 psi | 71% | 3087 fps | 95.2% |
| Alliant Reloder-50 | <<locked>> | 96% | 48,646 psi | 76% | 3150 fps | 95.7% |
| Baschieri & Pellagri 109 | <<locked>> | 82% | 45,672 psi | 72% | 3002 fps | 95.7% |
| Bofors RP15 | <<locked>> | 80% | 42,163 psi | 66% | 2969 fps | 98.3% |
| Bofors RP30 | <<locked>> | 80% | 35,752 psi | 56% | 2828 fps | 95.6% |
| Bofors RP5 | <<locked>> | 80% | 45,310 psi | 71% | 3041 fps | 99% |
| Hodgdon H1000 | <<locked>> | 80% | 36,100 psi | 57% | 2831 fps | 96.4% |
| Hodgdon H4831 | <<locked>> | 80% | 47,166 psi | 74% | 3038 fps | 98% |
| Hodgdon H4831 SC | <<locked>> | 80% | 46,209 psi | 72% | 3015 fps | 97.8% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 53,113 psi | 83% | 3074 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 80% | 37,362 psi | 59% | 2953 fps | 98% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,340 psi | 44% | 1880 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 47,834 psi | 75% | 3022 fps | 98.3% |
| IMR 7828 SSC | <<locked>> | 80% | 43,308 psi | 68% | 3018 fps | 97.7% |
| IMR 8133 Enduron | <<locked>> | 86% | 34,693 psi | 54% | 2818 fps | 95% |
| Lovex S071 | <<locked>> | 80% | 39,015 psi | 61% | 2825 fps | 99.4% |
| Norma 217 | <<locked>> | 82% | 30,414 psi | 48% | 2710 fps | 95.3% |
| Norma MRP | <<locked>> | 80% | 48,428 psi | 76% | 3120 fps | 99.9% |
| Ramshot Grand | <<locked>> | 80% | 43,758 psi | 69% | 3035 fps | 98.2% |
| Ramshot Magnum | <<locked>> | 80% | 39,479 psi | 62% | 2897 fps | 98.6% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,095 psi | 46% | 1923 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 36,912 psi | 58% | 2923 fps | 98.8% |
| ReloadSwiss RS 80 | <<locked>> | 84% | 39,523 psi | 62% | 2949 fps | 95.4% |
| Rottweil R 904 | <<locked>> | 80% | 49,908 psi | 78% | 3071 fps | 99% |
| Rottweil R 905 | <<locked>> | 80% | 48,834 psi | 77% | 3081 fps | 99.5% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 48,486 psi | 76% | 3077 fps | 99.5% |
| Somchem S361 | <<locked>> | 80% | 51,111 psi | 80% | 3058 fps | 98.8% |
| Somchem S385 | <<locked>> | 80% | 49,211 psi | 77% | 3051 fps | 99.9% |
| Vihtavuori N165 | <<locked>> | 80% | 43,091 psi | 68% | 2917 fps | 99% |
| Vihtavuori N170 | <<locked>> | 90% | 52,069 psi | 82% | 3114 fps | 95.5% |
| Vihtavuori N555 | <<locked>> | 80% | 48,747 psi | 76% | 3058 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 47,979 psi | 75% | 3117 fps | 98.3% |
| Vihtavuori N565 | <<locked>> | 80% | 40,001 psi | 63% | 2913 fps | 96.4% |
| Vihtavuori N568 | <<locked>> | 84% | 40,567 psi | 64% | 2966 fps | 95.2% |
| Vihtavuori N570 | <<locked>> | 90% | 48,124 psi | 75% | 3176 fps | 95.6% |
| Winchester StaBALL HD | <<locked>> | 80% | 43,033 psi | 67% | 3041 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 45,585 psi | 71% | 2979 fps | 99.1% |
ᴾ possible press load - work up slowly to this load while watching for signs of excessive pressure.
This overview compares 58 powders for .30-378 Weath. Mag. loaded with the .308 | 165gr | Speer Grand Slam. Hodgdon Retumbo delivers the highest muzzle velocity at 3,376 fps; across all powders the maximum-charge window runs from 2,096 fps to 3,376 fps. Accurate 8700 gives the best case fill at 100 %, and 58 of the 58 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (440 MPa), the top charges use 59–90 %, leaving at least 10 % headroom. The 165.0 gr projectile in 0.308" calls for a 1:15.5 twist; slower twists will usually not stabilise this weight. Accurate 8700, Alliant Reloder-50, Hodgdon TrailBoss 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. As outliers, Hodgdon US 869, Lovex D100, Ramshot LRT 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.