Load Specifications
Load data in caliber .338-378 Weath. Mag. with .338 | 225gr | Swift A-Frame bullet and 64 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Hodgdon Retumbo, ReloadSwiss RS 76 and ReloadSwiss RS 80.
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>> | 90% | 57,261 psi | 90% | 2943 fps | 100% |
| Accurate MAGPRO | <<locked>> | 88% | 56,086 psi | 88% | 3054 fps | 99.2% |
| ADI AR 2209 | <<locked>> | 86% | 54,955 psi | 86% | 2979 fps | 99.9% |
| ADI AR 2213 | <<locked>> | 90% | 56,869 psi | 89% | 3048 fps | 99.8% |
| ADI AR 2217 | <<locked>> | 98% | 55,274 psi | 87% | 3018 fps | 99.9% |
| ADI AR 2218ᴾ | <<locked>> | 100% | 51,706 psi | 81% | 3058 fps | 97.2% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 53,650 psi | 84% | 3041 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 82% | 55,187 psi | 86% | 2969 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 86% | 54,534 psi | 85% | 2966 fps | 99.9% |
| Alliant Reloder-22 | <<locked>> | 90% | 57,246 psi | 90% | 3045 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 90% | 55,245 psi | 87% | 2953 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 94% | 55,259 psi | 87% | 3022 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 86% | 55,898 psi | 88% | 3041 fps | 100% |
| Alliant Reloder-33ᴾ | <<locked>> | 100% | 57,072 psi | 89% | 3117 fps | 98.2% |
| Baschieri & Pellagri 109 | <<locked>> | 92% | 57,653 psi | 90% | 3009 fps | 98.3% |
| Bofors RP15 | <<locked>> | 92% | 56,579 psi | 89% | 3031 fps | 100% |
| Bofors RP30 | <<locked>> | 96% | 54,984 psi | 86% | 3035 fps | 99.8% |
| Bofors RP5 | <<locked>> | 90% | 57,246 psi | 90% | 3045 fps | 100% |
| Hodgdon H1000 | <<locked>> | 96% | 56,869 psi | 89% | 3045 fps | 100% |
| Hodgdon H4831 | <<locked>> | 88% | 56,318 psi | 88% | 2982 fps | 99.4% |
| Hodgdon H4831 SC | <<locked>> | 88% | 55,216 psi | 87% | 2966 fps | 99.3% |
| Hodgdon Hybrid 100V | <<locked>> | 84% | 55,317 psi | 87% | 2887 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 94% | 54,172 psi | 85% | 3107 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,550 psi | 59% | 1893 fps | 100% |
| IMR 4350 | <<locked>> | 84% | 57,464 psi | 90% | 2953 fps | 100% |
| IMR 4831 | <<locked>> | 82% | 54,331 psi | 85% | 2904 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 88% | 56,739 psi | 89% | 2959 fps | 99.5% |
| IMR 7828 SSC | <<locked>> | 90% | 55,259 psi | 87% | 3031 fps | 99.7% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 49,081 psi | 77% | 2953 fps | 99.3% |
| Lovex S065 | <<locked>> | 82% | 57,624 psi | 90% | 2927 fps | 100% |
| Lovex S070 | <<locked>> | 82% | 56,028 psi | 88% | 2930 fps | 100% |
| Lovex S071 | <<locked>> | 94% | 55,172 psi | 86% | 2913 fps | 100% |
| Norma 204 | <<locked>> | 82% | 54,940 psi | 86% | 2959 fps | 99.9% |
| Norma 217ᴾ | <<locked>> | 100% | 49,951 psi | 78% | 2982 fps | 100% |
| Norma MRP | <<locked>> | 88% | 57,363 psi | 90% | 3061 fps | 100% |
| Norma URP | <<locked>> | 82% | 55,898 psi | 88% | 2946 fps | 100% |
| Ramshot Grand | <<locked>> | 90% | 56,362 psi | 88% | 3054 fps | 99.9% |
| Ramshot Hunter | <<locked>> | 82% | 54,911 psi | 86% | 2956 fps | 100% |
| Ramshot Magnum | <<locked>> | 92% | 54,752 psi | 86% | 2982 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,522 psi | 60% | 1939 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 82% | 56,507 psi | 89% | 3015 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 94% | 54,810 psi | 86% | 3094 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 96% | 54,215 psi | 85% | 3054 fps | 99.2% |
| Rottweil R 904 | <<locked>> | 86% | 55,622 psi | 87% | 2946 fps | 99.6% |
| Rottweil R 905 | <<locked>> | 86% | 54,302 psi | 85% | 2959 fps | 99.9% |
| Shooters World Long Rifle | <<locked>> | 82% | 57,624 psi | 90% | 2927 fps | 100% |
| Shooters World SW4350 | <<locked>> | 82% | 56,028 psi | 88% | 2930 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 82% | 56,652 psi | 89% | 2884 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 88% | 57,522 psi | 90% | 3012 fps | 100% |
| Somchem S361 | <<locked>> | 86% | 57,145 psi | 90% | 2940 fps | 99.5% |
| Somchem S365 | <<locked>> | 84% | 57,276 psi | 90% | 2949 fps | 100% |
| Somchem S385 | <<locked>> | 86% | 54,592 psi | 86% | 2927 fps | 100% |
| Vihtavuori N160 | <<locked>> | 82% | 57,537 psi | 90% | 2936 fps | 100% |
| Vihtavuori N165 | <<locked>> | 90% | 54,462 psi | 85% | 2913 fps | 100% |
| Vihtavuori N170 | <<locked>> | 96% | 57,246 psi | 90% | 2989 fps | 96.7% |
| Vihtavuori N550 | <<locked>> | 82% | 56,666 psi | 89% | 2940 fps | 100% |
| Vihtavuori N555 | <<locked>> | 88% | 57,319 psi | 90% | 2979 fps | 100% |
| Vihtavuori N560 | <<locked>> | 88% | 56,855 psi | 89% | 3064 fps | 99.6% |
| Vihtavuori N565 | <<locked>> | 94% | 57,479 psi | 90% | 3051 fps | 99.7% |
| Vihtavuori N568 | <<locked>> | 96% | 54,969 psi | 86% | 3058 fps | 98.9% |
| Vihtavuori N570 | <<locked>> | 98% | 55,985 psi | 88% | 3117 fps | 97.7% |
| Winchester 6.5 StaBALL | <<locked>> | 82% | 56,869 psi | 89% | 2881 fps | 100% |
| Winchester StaBALL HD | <<locked>> | 90% | 54,607 psi | 86% | 3038 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 88% | 54,375 psi | 85% | 2923 fps | 99.9% |
Recommended = one of the top powders for this cartridge and bullet combination.
Start Load - Barrel Length: 26"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 3100 | <<locked>> | 80% | 40,872 psi | 64% | 2671 fps | 99.7% |
| Accurate MAGPRO | <<locked>> | 80% | 42,235 psi | 66% | 2792 fps | 96.4% |
| ADI AR 2209 | <<locked>> | 80% | 44,860 psi | 70% | 2802 fps | 99% |
| ADI AR 2213 | <<locked>> | 80% | 40,176 psi | 63% | 2736 fps | 97% |
| ADI AR 2217 | <<locked>> | 84% | 34,287 psi | 54% | 2592 fps | 95.1% |
| ADI AR 2218 | <<locked>> | 98% | 48,008 psi | 75% | 2982 fps | 96.1% |
| ADI AR 2225 | <<locked>> | 82% | 29,298 psi | 46% | 2497 fps | 96% |
| Alliant Reloder-16 | <<locked>> | 80% | 51,619 psi | 81% | 2913 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 80% | 44,831 psi | 70% | 2795 fps | 99% |
| Alliant Reloder-22 | <<locked>> | 80% | 40,814 psi | 64% | 2746 fps | 98.3% |
| Alliant Reloder-23 | <<locked>> | 80% | 39,610 psi | 62% | 2690 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 34,185 psi | 54% | 2621 fps | 99.3% |
| Alliant Reloder-26 | <<locked>> | 80% | 44,512 psi | 70% | 2854 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 94% | 45,455 psi | 71% | 2907 fps | 95.5% |
| Baschieri & Pellagri 109 | <<locked>> | 84% | 44,730 psi | 70% | 2772 fps | 95.3% |
| Bofors RP15 | <<locked>> | 80% | 38,029 psi | 60% | 2680 fps | 97.4% |
| Bofors RP30 | <<locked>> | 82% | 34,055 psi | 53% | 2608 fps | 95.3% |
| Bofors RP5 | <<locked>> | 80% | 40,814 psi | 64% | 2746 fps | 98.3% |
| Hodgdon H1000 | <<locked>> | 82% | 34,896 psi | 55% | 2612 fps | 96.1% |
| Hodgdon H4831 | <<locked>> | 80% | 42,873 psi | 67% | 2740 fps | 97.1% |
| Hodgdon H4831 SC | <<locked>> | 80% | 42,018 psi | 66% | 2723 fps | 96.8% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 48,588 psi | 76% | 2789 fps | 100% |
| Hodgdon Retumbo | 93.8 gr | 80% | 33,344 psi | 52% | 2651 fps | 96.7% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,123 psi | 44% | 1693 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 50,560 psi | 79% | 2844 fps | 99.9% |
| IMR 4831 | <<locked>> | 80% | 50,966 psi | 80% | 2851 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 44,034 psi | 69% | 2736 fps | 97.5% |
| IMR 7828 SSC | <<locked>> | 80% | 38,885 psi | 61% | 2720 fps | 96.6% |
| IMR 8133 Enduron | <<locked>> | 90% | 34,882 psi | 55% | 2651 fps | 95.5% |
| Lovex S065 | <<locked>> | 80% | 54,172 psi | 85% | 2877 fps | 100% |
| Lovex S070 | <<locked>> | 80% | 52,620 psi | 82% | 2877 fps | 100% |
| Lovex S071 | <<locked>> | 80% | 35,302 psi | 55% | 2549 fps | 98.8% |
| Norma 204 | <<locked>> | 80% | 51,343 psi | 80% | 2897 fps | 99.7% |
| Norma 217 | <<locked>> | 86% | 30,618 psi | 48% | 2556 fps | 96% |
| Norma MRP | <<locked>> | 80% | 43,279 psi | 68% | 2818 fps | 99.6% |
| Norma URP | <<locked>> | 80% | 52,373 psi | 82% | 2894 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 38,812 psi | 61% | 2726 fps | 97% |
| Ramshot Hunter | <<locked>> | 80% | 51,387 psi | 81% | 2900 fps | 100% |
| Ramshot Magnum | <<locked>> | 80% | 34,795 psi | 55% | 2605 fps | 97.5% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 28,950 psi | 45% | 1736 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 52,562 psi | 82% | 2959 fps | 100% |
| ReloadSwiss RS 76 | 100.4 gr | 80% | 32,518 psi | 51% | 2625 fps | 97.6% |
| ReloadSwiss RS 80 | 111.4 gr | 88% | 39,943 psi | 63% | 2782 fps | 96% |
| Rottweil R 904 | <<locked>> | 80% | 45,847 psi | 72% | 2776 fps | 98.4% |
| Rottweil R 905 | <<locked>> | 80% | 44,396 psi | 70% | 2782 fps | 99% |
| Shooters World Long Rifle | <<locked>> | 80% | 54,172 psi | 85% | 2877 fps | 100% |
| Shooters World SW4350 | <<locked>> | 80% | 52,620 psi | 82% | 2877 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 52,982 psi | 83% | 2828 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 44,063 psi | 69% | 2779 fps | 99% |
| Somchem S361 | <<locked>> | 80% | 46,775 psi | 73% | 2762 fps | 98% |
| Somchem S365 | <<locked>> | 80% | 49,995 psi | 78% | 2844 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 44,831 psi | 70% | 2759 fps | 99.5% |
| Vihtavuori N160 | <<locked>> | 80% | 53,795 psi | 84% | 2881 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 39,088 psi | 61% | 2635 fps | 98.3% |
| Vihtavuori N170 | <<locked>> | 94% | 53,403 psi | 84% | 2923 fps | 95.8% |
| Vihtavuori N550 | <<locked>> | 80% | 53,185 psi | 83% | 2890 fps | 100% |
| Vihtavuori N555 | <<locked>> | 80% | 44,106 psi | 69% | 2769 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 43,076 psi | 68% | 2812 fps | 97.3% |
| Vihtavuori N565 | <<locked>> | 80% | 35,723 psi | 56% | 2628 fps | 95.1% |
| Vihtavuori N568 | <<locked>> | 88% | 41,220 psi | 65% | 2799 fps | 95.8% |
| Vihtavuori N570 | <<locked>> | 94% | 48,399 psi | 76% | 2982 fps | 95.9% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 53,098 psi | 83% | 2831 fps | 100% |
| Winchester StaBALL HD | <<locked>> | 80% | 37,188 psi | 58% | 2743 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 41,292 psi | 65% | 2690 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 64 powders for .338-378 Weath. Mag. loaded with the .338 | 225gr | Swift A-Frame. Alliant Reloder-33 delivers the highest muzzle velocity at 3,117 fps; across all powders the maximum-charge window runs from 1,893 fps to 3,117 fps. ADI AR 2218 gives the best case fill at 100 %, and 64 of the 64 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 225.0 gr projectile in 0.338" calls for a 1:16.5 twist; slower twists will usually not stabilise this weight. ADI AR 2218, ADI AR 2225, Alliant Reloder-33 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. Hodgdon Retumbo, ReloadSwiss RS 76, ReloadSwiss RS 80 rank at the top here: for .338-378 Weath. Mag. with the .338 | 225gr | Swift A-Frame 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.