Load Specifications
Load data in caliber .338-378 Weath. Mag. with .338 | 248gr | Peregrine VLR-4 bullet and 72 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% | 54,694 psi | 86% | 2779 fps | 100% |
| Accurate 4350 | <<locked>> | 82% | 55,434 psi | 87% | 2795 fps | 100% |
| Accurate High Country | <<locked>> | 88% | 56,739 psi | 89% | 2940 fps | 99.9% |
| Accurate MAGPRO | <<locked>> | 90% | 57,667 psi | 90% | 2946 fps | 99.6% |
| ADI AR 2209 | <<locked>> | 88% | 56,608 psi | 89% | 2871 fps | 100% |
| ADI AR 2213 | <<locked>> | 90% | 54,650 psi | 86% | 2884 fps | 99.8% |
| ADI AR 2217ᴾ | <<locked>> | 100% | 56,652 psi | 89% | 2910 fps | 100% |
| ADI AR 2218ᴾ | <<locked>> | 100% | 49,124 psi | 77% | 2887 fps | 97.1% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 51,039 psi | 80% | 2874 fps | 100% |
| Alliant Power Pro Varmint | <<locked>> | 88% | 56,898 psi | 89% | 2867 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 84% | 56,898 psi | 89% | 2854 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 88% | 56,260 psi | 88% | 2861 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 90% | 54,911 psi | 86% | 2877 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 92% | 56,565 psi | 89% | 2835 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 96% | 56,536 psi | 89% | 2907 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 88% | 57,174 psi | 90% | 2927 fps | 100% |
| Alliant Reloder-33ᴾ | <<locked>> | 100% | 53,824 psi | 84% | 2943 fps | 98.2% |
| Baschieri & Pellagri 109 | <<locked>> | 92% | 55,666 psi | 87% | 2848 fps | 98.4% |
| Bofors RP15 | <<locked>> | 92% | 54,288 psi | 85% | 2867 fps | 100% |
| Bofors RP30 | <<locked>> | 98% | 56,130 psi | 88% | 2923 fps | 100% |
| Bofors RP5 | <<locked>> | 90% | 54,911 psi | 86% | 2877 fps | 100% |
| Bofors RP7 | <<locked>> | 82% | 57,072 psi | 89% | 2799 fps | 100% |
| Hodgdon H1000 | <<locked>> | 96% | 54,375 psi | 85% | 2877 fps | 100% |
| Hodgdon H414 | <<locked>> | 82% | 57,116 psi | 90% | 2854 fps | 100% |
| Hodgdon H4831 | <<locked>> | 88% | 54,215 psi | 85% | 2818 fps | 99.5% |
| Hodgdon H4831 SC | <<locked>> | 90% | 56,840 psi | 89% | 2858 fps | 99.7% |
| Hodgdon Hybrid 100V | <<locked>> | 86% | 56,956 psi | 89% | 2772 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 96% | 55,390 psi | 87% | 2992 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,434 psi | 59% | 1775 fps | 100% |
| IMR 4350 | <<locked>> | 84% | 55,695 psi | 87% | 2792 fps | 100% |
| IMR 4831 | <<locked>> | 84% | 55,941 psi | 88% | 2789 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 88% | 54,897 psi | 86% | 2799 fps | 99.6% |
| IMR 7828 SSC | <<locked>> | 92% | 56,826 psi | 89% | 2923 fps | 99.9% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 46,485 psi | 73% | 2789 fps | 99.3% |
| Lovex S065 | <<locked>> | 82% | 55,782 psi | 87% | 2766 fps | 100% |
| Lovex S070 | <<locked>> | 84% | 57,711 psi | 90% | 2818 fps | 100% |
| Lovex S071 | <<locked>> | 96% | 56,086 psi | 88% | 2799 fps | 100% |
| Norma 204 | <<locked>> | 84% | 56,797 psi | 89% | 2851 fps | 100% |
| Norma 217ᴾ | <<locked>> | 100% | 47,079 psi | 74% | 2815 fps | 100% |
| Norma MRP | <<locked>> | 88% | 54,998 psi | 86% | 2894 fps | 100% |
| Norma URP | <<locked>> | 84% | 57,638 psi | 90% | 2831 fps | 100% |
| Ramshot Grand | <<locked>> | 90% | 53,635 psi | 84% | 2881 fps | 99.9% |
| Ramshot Hunter | <<locked>> | 84% | 56,565 psi | 89% | 2844 fps | 100% |
| Ramshot Magnum | <<locked>> | 94% | 56,217 psi | 88% | 2874 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,319 psi | 60% | 1818 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 82% | 55,709 psi | 87% | 2822 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 82% | 54,418 psi | 85% | 2854 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 96% | 56,014 psi | 88% | 2982 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 98% | 55,332 psi | 87% | 2949 fps | 99.6% |
| Rottweil R 904 | <<locked>> | 88% | 57,377 psi | 90% | 2838 fps | 99.9% |
| Rottweil R 905 | <<locked>> | 88% | 55,724 psi | 87% | 2848 fps | 100% |
| Rottweil R 907 | <<locked>> | 82% | 57,072 psi | 89% | 2799 fps | 100% |
| Shooters World Long Rifle | <<locked>> | 82% | 55,782 psi | 87% | 2766 fps | 100% |
| Shooters World SW4350 | <<locked>> | 84% | 57,711 psi | 90% | 2818 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 82% | 54,737 psi | 86% | 2720 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 88% | 55,317 psi | 87% | 2844 fps | 100% |
| Somchem S361 | <<locked>> | 86% | 55,085 psi | 86% | 2779 fps | 99.5% |
| Somchem S365 | <<locked>> | 84% | 55,042 psi | 86% | 2785 fps | 100% |
| Somchem S385 | <<locked>> | 88% | 56,101 psi | 88% | 2818 fps | 100% |
| Vihtavuori N160 | <<locked>> | 82% | 55,521 psi | 87% | 2772 fps | 100% |
| Vihtavuori N165 | <<locked>> | 92% | 55,854 psi | 88% | 2802 fps | 100% |
| Vihtavuori N170 | <<locked>> | 96% | 54,665 psi | 86% | 2822 fps | 96.7% |
| Vihtavuori N550 | <<locked>> | 82% | 54,665 psi | 86% | 2779 fps | 100% |
| Vihtavuori N555 | <<locked>> | 88% | 54,795 psi | 86% | 2812 fps | 100% |
| Vihtavuori N560 | <<locked>> | 88% | 54,665 psi | 86% | 2897 fps | 99.6% |
| Vihtavuori N565 | <<locked>> | 94% | 54,824 psi | 86% | 2884 fps | 99.8% |
| Vihtavuori N568 | <<locked>> | 98% | 56,043 psi | 88% | 2949 fps | 99.4% |
| Vihtavuori N570ᴾ | <<locked>> | 100% | 57,188 psi | 90% | 3012 fps | 98.4% |
| Winchester 6.5 StaBALL | <<locked>> | 82% | 54,984 psi | 86% | 2726 fps | 100% |
| Winchester 760 | <<locked>> | 82% | 57,276 psi | 90% | 2858 fps | 100% |
| Winchester StaBALL HD | <<locked>> | 92% | 55,796 psi | 87% | 2923 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 90% | 56,043 psi | 88% | 2818 fps | 100% |
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% | 38,827 psi | 61% | 2516 fps | 99.7% |
| Accurate 4350 | <<locked>> | 80% | 51,808 psi | 81% | 2746 fps | 100% |
| Accurate High Country | <<locked>> | 80% | 42,612 psi | 67% | 2697 fps | 98.3% |
| Accurate MAGPRO | <<locked>> | 80% | 40,248 psi | 63% | 2638 fps | 96.5% |
| ADI AR 2209 | <<locked>> | 80% | 43,192 psi | 68% | 2648 fps | 99.1% |
| ADI AR 2213 | <<locked>> | 80% | 38,537 psi | 60% | 2585 fps | 97.1% |
| ADI AR 2217 | <<locked>> | 84% | 32,677 psi | 51% | 2444 fps | 95.2% |
| ADI AR 2218 | <<locked>> | 98% | 45,585 psi | 71% | 2815 fps | 96% |
| ADI AR 2225 | <<locked>> | 82% | 27,659 psi | 43% | 2352 fps | 96% |
| Alliant Power Pro Varmint | <<locked>> | 80% | 43,598 psi | 68% | 2648 fps | 99.1% |
| Alliant Reloder-16 | <<locked>> | 80% | 49,937 psi | 78% | 2753 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 80% | 43,192 psi | 68% | 2641 fps | 99.1% |
| Alliant Reloder-22 | <<locked>> | 80% | 38,986 psi | 61% | 2592 fps | 98.4% |
| Alliant Reloder-23 | <<locked>> | 80% | 37,710 psi | 59% | 2539 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 32,474 psi | 51% | 2470 fps | 99.3% |
| Alliant Reloder-26 | <<locked>> | 80% | 42,163 psi | 66% | 2694 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 94% | 42,757 psi | 67% | 2740 fps | 95.4% |
| Baschieri & Pellagri 109 | <<locked>> | 84% | 43,279 psi | 68% | 2621 fps | 95.5% |
| Bofors RP15 | <<locked>> | 80% | 36,318 psi | 57% | 2530 fps | 97.6% |
| Bofors RP30 | <<locked>> | 82% | 32,039 psi | 50% | 2457 fps | 95.3% |
| Bofors RP5 | <<locked>> | 80% | 38,986 psi | 61% | 2592 fps | 98.4% |
| Bofors RP7 | <<locked>> | 80% | 53,563 psi | 84% | 2749 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 30,951 psi | 49% | 2398 fps | 95% |
| Hodgdon H414 | <<locked>> | 80% | 53,417 psi | 84% | 2802 fps | 100% |
| Hodgdon H4831 | <<locked>> | 80% | 41,162 psi | 65% | 2589 fps | 97.2% |
| Hodgdon H4831 SC | <<locked>> | 80% | 40,379 psi | 63% | 2572 fps | 97% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 46,804 psi | 73% | 2631 fps | 100% |
| Hodgdon Retumbo | 86.2 gr | 80% | 31,763 psi | 50% | 2503 fps | 96.8% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,065 psi | 44% | 1588 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 48,965 psi | 77% | 2687 fps | 100% |
| IMR 4831 | <<locked>> | 80% | 48,994 psi | 77% | 2690 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 42,496 psi | 67% | 2582 fps | 97.7% |
| IMR 7828 SSC | <<locked>> | 80% | 37,275 psi | 58% | 2569 fps | 96.8% |
| IMR 8133 Enduron | <<locked>> | 90% | 32,822 psi | 51% | 2497 fps | 95.5% |
| Lovex S065 | <<locked>> | 80% | 52,373 psi | 82% | 2713 fps | 100% |
| Lovex S070 | <<locked>> | 80% | 50,894 psi | 80% | 2717 fps | 100% |
| Lovex S071 | <<locked>> | 80% | 33,286 psi | 52% | 2395 fps | 98.8% |
| Norma 204 | <<locked>> | 80% | 49,545 psi | 78% | 2736 fps | 99.7% |
| Norma 217 | <<locked>> | 86% | 28,645 psi | 45% | 2402 fps | 95.9% |
| Norma MRP | <<locked>> | 80% | 41,205 psi | 65% | 2661 fps | 99.6% |
| Norma URP | <<locked>> | 80% | 50,618 psi | 79% | 2733 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 36,970 psi | 58% | 2572 fps | 97.1% |
| Ramshot Hunter | <<locked>> | 80% | 49,501 psi | 78% | 2740 fps | 100% |
| Ramshot Magnum | <<locked>> | 80% | 32,837 psi | 51% | 2454 fps | 97.5% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 28,674 psi | 45% | 1624 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 52,025 psi | 82% | 2772 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 50,560 psi | 79% | 2795 fps | 100% |
| ReloadSwiss RS 76 | 92.2 gr | 80% | 30,705 psi | 48% | 2474 fps | 97.6% |
| ReloadSwiss RS 80 | 102.2 gr | 88% | 37,420 psi | 59% | 2621 fps | 95.9% |
| Rottweil R 904 | <<locked>> | 80% | 44,309 psi | 69% | 2621 fps | 98.5% |
| Rottweil R 905 | <<locked>> | 80% | 42,540 psi | 67% | 2628 fps | 99.1% |
| Rottweil R 907 | <<locked>> | 80% | 53,563 psi | 84% | 2749 fps | 100% |
| Shooters World Long Rifle | <<locked>> | 80% | 52,373 psi | 82% | 2713 fps | 100% |
| Shooters World SW4350 | <<locked>> | 80% | 50,894 psi | 80% | 2717 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 51,314 psi | 80% | 2671 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 42,221 psi | 66% | 2625 fps | 99% |
| Somchem S361 | <<locked>> | 80% | 45,063 psi | 71% | 2612 fps | 98.1% |
| Somchem S365 | <<locked>> | 80% | 47,935 psi | 75% | 2684 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 42,975 psi | 67% | 2605 fps | 99.6% |
| Vihtavuori N160 | <<locked>> | 80% | 52,040 psi | 82% | 2723 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 37,405 psi | 59% | 2487 fps | 98.4% |
| Vihtavuori N170 | <<locked>> | 94% | 51,111 psi | 80% | 2766 fps | 95.9% |
| Vihtavuori N550 | <<locked>> | 80% | 51,169 psi | 80% | 2726 fps | 100% |
| Vihtavuori N555 | <<locked>> | 80% | 42,018 psi | 66% | 2612 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 41,147 psi | 64% | 2654 fps | 97.4% |
| Vihtavuori N565 | <<locked>> | 80% | 33,663 psi | 53% | 2470 fps | 95.1% |
| Vihtavuori N568 | <<locked>> | 88% | 38,972 psi | 61% | 2641 fps | 95.8% |
| Vihtavuori N570 | <<locked>> | 94% | 45,905 psi | 72% | 2818 fps | 95.9% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 51,300 psi | 80% | 2677 fps | 100% |
| Winchester 760 | <<locked>> | 80% | 53,577 psi | 84% | 2805 fps | 100% |
| Winchester StaBALL HD | <<locked>> | 80% | 34,882 psi | 55% | 2585 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 39,407 psi | 62% | 2536 fps | 98.4% |
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 72 powders for .338-378 Weath. Mag. loaded with the .338 | 248gr | Peregrine VLR-4. Vihtavuori N570 delivers the highest muzzle velocity at 3,012 fps; across all powders the maximum-charge window runs from 1,775 fps to 3,012 fps. ADI AR 2217 gives the best case fill at 100 %, and 72 of the 72 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 248.0 gr projectile in 0.338" calls for a 1:10.5 twist; slower twists will usually not stabilise this weight. ADI AR 2217, ADI AR 2218, ADI AR 2225 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 | 248gr | Peregrine VLR-4 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.