Load Specifications
Load data in caliber .338 Blaser Mag. with .338 | 250gr | Nosler Partition RN bullet and 97 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-26 and Hodgdon Superformance.
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.
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You can find more information in our FAQ: How can I use the Personalized Load Calculator?
Max Load - Barrel Length: 25.6"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 2495 | <<locked>> | 82% | 52,634 psi | 86% | 2477 fps | 100% |
| Accurate 2700 | <<locked>> | 86% | 51,837 psi | 85% | 2507 fps | 98.8% |
| Accurate 3100ᴾ | <<locked>> | 100% | 50,618 psi | 83% | 2582 fps | 99.7% |
| Accurate 4064 | <<locked>> | 84% | 53,127 psi | 87% | 2530 fps | 100% |
| Accurate 4350 | <<locked>> | 92% | 53,113 psi | 87% | 2628 fps | 100% |
| ADI AR 2208 | <<locked>> | 86% | 53,287 psi | 87% | 2559 fps | 100% |
| ADI AR 2209 | <<locked>> | 98% | 54,346 psi | 89% | 2674 fps | 98.7% |
| ADI AR 2213ᴾ | <<locked>> | 100% | 51,822 psi | 85% | 2664 fps | 97.1% |
| Alliant Power Pro 2000-MR | <<locked>> | 82% | 52,112 psi | 86% | 2671 fps | 100% |
| Alliant Power Pro Varmint | <<locked>> | 98% | 54,070 psi | 89% | 2667 fps | 98.7% |
| Alliant Power Pro Varmint | <<locked>> | 98% | 54,070 psi | 89% | 2667 fps | 98.7% |
| Alliant Reloder- TS 15.5 | <<locked>> | 86% | 54,012 psi | 89% | 2582 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 84% | 54,186 psi | 89% | 2602 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 94% | 54,041 psi | 89% | 2680 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 88% | 51,372 psi | 84% | 2651 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 98% | 53,301 psi | 88% | 2661 fps | 98.6% |
| Alliant Reloder-22ᴾ | <<locked>> | 100% | 50,314 psi | 83% | 2661 fps | 98.4% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 47,543 psi | 78% | 2602 fps | 100% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 41,553 psi | 68% | 2536 fps | 99.3% |
| Alliant Reloder-26ᴾ | <<locked>> | 100% | 54,143 psi | 89% | 2779 fps | 100% |
| Bofors RP15ᴾ | <<locked>> | 100% | 46,224 psi | 76% | 2592 fps | 97.4% |
| Bofors RP3 | <<locked>> | 86% | 54,621 psi | 90% | 2595 fps | 100% |
| Bofors RP5ᴾ | <<locked>> | 100% | 50,314 psi | 83% | 2661 fps | 98.4% |
| Bofors RP7 | <<locked>> | 90% | 54,114 psi | 89% | 2585 fps | 99.2% |
| Hodgdon H380 | <<locked>> | 84% | 51,721 psi | 85% | 2566 fps | 100% |
| Hodgdon H414 | <<locked>> | 88% | 53,171 psi | 87% | 2648 fps | 99.5% |
| Hodgdon H4350 | <<locked>> | 92% | 53,766 psi | 88% | 2615 fps | 98.8% |
| Hodgdon H4831 SCᴾ | <<locked>> | 100% | 54,375 psi | 89% | 2648 fps | 97% |
| Hodgdon Hybrid 100V | <<locked>> | 96% | 54,331 psi | 89% | 2608 fps | 100% |
| Hodgdon LEVERevolution | <<locked>> | 84% | 53,055 psi | 87% | 2602 fps | 100% |
| Hodgdon Retumboᴾ | <<locked>> | 100% | 40,683 psi | 67% | 2559 fps | 96.6% |
| Hodgdon Superformance | <<locked>> | 90% | 51,764 psi | 85% | 2664 fps | 99.3% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 36,245 psi | 60% | 1578 fps | 100% |
| Hodgdon VARGET | <<locked>> | 84% | 52,968 psi | 87% | 2549 fps | 100% |
| IMR 3031 | <<locked>> | 82% | 52,257 psi | 86% | 2520 fps | 100% |
| IMR 4064 | <<locked>> | 86% | 52,431 psi | 86% | 2536 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 88% | 54,520 psi | 90% | 2562 fps | 99.5% |
| IMR 4350 | <<locked>> | 94% | 54,781 psi | 90% | 2615 fps | 99.3% |
| IMR 4451 Enduron | <<locked>> | 88% | 52,576 psi | 86% | 2562 fps | 99.3% |
| IMR 4831 | <<locked>> | 98% | 54,462 psi | 89% | 2631 fps | 100% |
| IMR 4895 | <<locked>> | 82% | 52,127 psi | 86% | 2575 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 98% | 53,983 psi | 89% | 2608 fps | 97.1% |
| IMR 7828 SSCᴾ | <<locked>> | 100% | 53,084 psi | 87% | 2697 fps | 97.5% |
| Lovex S060 | <<locked>> | 82% | 54,563 psi | 90% | 2526 fps | 100% |
| Lovex S062 | <<locked>> | 84% | 52,968 psi | 87% | 2536 fps | 100% |
| Lovex S065 | <<locked>> | 90% | 52,489 psi | 86% | 2559 fps | 99.9% |
| Lovex S070 | <<locked>> | 92% | 53,577 psi | 88% | 2598 fps | 99.6% |
| Lovex S071ᴾ | <<locked>> | 100% | 42,163 psi | 69% | 2451 fps | 98.7% |
| Norma 201 | <<locked>> | 82% | 54,302 psi | 89% | 2543 fps | 100% |
| Norma 202 | <<locked>> | 82% | 55,114 psi | 90% | 2543 fps | 100% |
| Norma 203B | <<locked>> | 84% | 53,476 psi | 88% | 2589 fps | 100% |
| Norma 204 | <<locked>> | 92% | 51,793 psi | 85% | 2612 fps | 98.2% |
| Norma MRPᴾ | <<locked>> | 100% | 53,330 psi | 88% | 2740 fps | 99.6% |
| Norma URP | <<locked>> | 92% | 52,156 psi | 86% | 2618 fps | 100% |
| Ramshot Big Game | <<locked>> | 84% | 54,114 psi | 89% | 2615 fps | 100% |
| Ramshot Grand | <<locked>> | 98% | 52,707 psi | 87% | 2700 fps | 97.8% |
| Ramshot Hunter | <<locked>> | 94% | 54,317 psi | 89% | 2671 fps | 99.9% |
| Ramshot Magnumᴾ | <<locked>> | 100% | 49,269 psi | 81% | 2625 fps | 98.6% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 36,927 psi | 61% | 1617 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 86% | 54,940 psi | 90% | 2598 fps | 99.8% |
| ReloadSwiss RS 52 | <<locked>> | 82% | 54,984 psi | 90% | 2661 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 88% | 54,665 psi | 90% | 2694 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 92% | 52,953 psi | 87% | 2654 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 94% | 55,100 psi | 90% | 2730 fps | 100% |
| ReloadSwiss RS 76ᴾ | <<locked>> | 100% | 40,321 psi | 66% | 2552 fps | 97.6% |
| Rottweil R 902 | <<locked>> | 84% | 55,042 psi | 90% | 2546 fps | 100% |
| Rottweil R 903 | <<locked>> | 88% | 54,766 psi | 90% | 2592 fps | 100% |
| Rottweil R 904 | <<locked>> | 96% | 52,678 psi | 86% | 2595 fps | 97.4% |
| Rottweil R 905 | <<locked>> | 98% | 52,562 psi | 86% | 2648 fps | 98.6% |
| Rottweil R 907 | <<locked>> | 90% | 54,114 psi | 89% | 2585 fps | 99.2% |
| Shooters World Long Rifle | <<locked>> | 90% | 52,489 psi | 86% | 2559 fps | 99.9% |
| Shooters World Precision | <<locked>> | 84% | 52,968 psi | 87% | 2536 fps | 100% |
| Shooters World SW4350 | <<locked>> | 92% | 53,577 psi | 88% | 2598 fps | 99.6% |
| SNPE Vectan SP 11 | <<locked>> | 86% | 52,750 psi | 87% | 2602 fps | 100% |
| SNPE Vectan SP 9 | <<locked>> | 82% | 53,954 psi | 89% | 2575 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 86% | 52,852 psi | 87% | 2441 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 90% | 52,141 psi | 86% | 2516 fps | 99.3% |
| SNPE Vectan Tubal 8000 | <<locked>> | 98% | 52,083 psi | 86% | 2641 fps | 98.6% |
| Somchem S335 | <<locked>> | 82% | 54,853 psi | 90% | 2477 fps | 100% |
| Somchem S355 | <<locked>> | 88% | 54,810 psi | 90% | 2589 fps | 100% |
| Somchem S361 | <<locked>> | 96% | 54,201 psi | 89% | 2589 fps | 96.9% |
| Somchem S365 | <<locked>> | 96% | 54,476 psi | 89% | 2664 fps | 100% |
| Somchem S385 | <<locked>> | 98% | 53,200 psi | 87% | 2625 fps | 99.2% |
| Unknown powder | <<locked>> | 90% | 52,678 psi | 86% | 2618 fps | 100% |
| Vihtavuori N135 | <<locked>> | 82% | 52,098 psi | 86% | 2464 fps | 100% |
| Vihtavuori N140 | <<locked>> | 82% | 52,243 psi | 86% | 2480 fps | 100% |
| Vihtavuori N150 | <<locked>> | 88% | 52,634 psi | 86% | 2520 fps | 100% |
| Vihtavuori N160 | <<locked>> | 92% | 54,186 psi | 89% | 2608 fps | 100% |
| Vihtavuori N165ᴾ | <<locked>> | 100% | 48,979 psi | 80% | 2549 fps | 98.3% |
| Vihtavuori N540 | <<locked>> | 84% | 53,751 psi | 88% | 2523 fps | 100% |
| Vihtavuori N550 | <<locked>> | 92% | 53,301 psi | 88% | 2618 fps | 100% |
| Vihtavuori N555ᴾ | <<locked>> | 100% | 53,330 psi | 88% | 2671 fps | 100% |
| Vihtavuori N560ᴾ | <<locked>> | 100% | 53,838 psi | 88% | 2730 fps | 97.4% |
| Winchester 6.5 StaBALL | <<locked>> | 92% | 53,737 psi | 88% | 2582 fps | 100% |
| Winchester 760 | <<locked>> | 88% | 53,171 psi | 87% | 2648 fps | 99.5% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 42,801 psi | 70% | 2654 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 96% | 51,343 psi | 84% | 2592 fps | 98.2% |
Recommended = one of the top powders for this cartridge and bullet combination.
Start Load - Barrel Length: 25.6"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 2495 | <<locked>> | 80% | 49,487 psi | 81% | 2434 fps | 100% |
| Accurate 2700 | <<locked>> | 80% | 42,569 psi | 70% | 2356 fps | 97.2% |
| Accurate 3100 | <<locked>> | 86% | 31,618 psi | 52% | 2241 fps | 95.8% |
| Accurate 4064 | <<locked>> | 80% | 46,891 psi | 77% | 2444 fps | 100% |
| Accurate 4350 | <<locked>> | 80% | 35,418 psi | 58% | 2333 fps | 98.6% |
| ADI AR 2208 | <<locked>> | 80% | 44,353 psi | 73% | 2421 fps | 99.9% |
| ADI AR 2209 | <<locked>> | 88% | 39,334 psi | 65% | 2415 fps | 95.3% |
| ADI AR 2213 | <<locked>> | 96% | 45,382 psi | 75% | 2552 fps | 95.5% |
| Alliant Power Pro 2000-MR | <<locked>> | 80% | 48,515 psi | 80% | 2618 fps | 100% |
| Alliant Power Pro Varmint | <<locked>> | 88% | 39,450 psi | 65% | 2415 fps | 95.5% |
| Alliant Power Pro Varmint | <<locked>> | 88% | 39,450 psi | 65% | 2415 fps | 95.5% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 44,744 psi | 73% | 2444 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 80% | 47,834 psi | 79% | 2507 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 80% | 34,737 psi | 57% | 2339 fps | 98.7% |
| Alliant Reloder-17 | <<locked>> | 80% | 39,204 psi | 64% | 2454 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 88% | 39,015 psi | 64% | 2411 fps | 95.4% |
| Alliant Reloder-22 | <<locked>> | 92% | 38,899 psi | 64% | 2454 fps | 95.6% |
| Alliant Reloder-23 | <<locked>> | 80% | 25,454 psi | 42% | 2126 fps | 96.7% |
| Alliant Reloder-25 | <<locked>> | 90% | 30,560 psi | 50% | 2280 fps | 95.7% |
| Alliant Reloder-26 | 65 gr | 82% | 28,747 psi | 47% | 2277 fps | 95.9% |
| Bofors RP15 | <<locked>> | 94% | 38,232 psi | 63% | 2438 fps | 95.1% |
| Bofors RP3 | <<locked>> | 80% | 44,875 psi | 74% | 2454 fps | 100% |
| Bofors RP5 | <<locked>> | 92% | 38,899 psi | 64% | 2454 fps | 95.6% |
| Bofors RP7 | <<locked>> | 80% | 39,769 psi | 65% | 2343 fps | 96.7% |
| Hodgdon H380 | <<locked>> | 80% | 45,411 psi | 75% | 2467 fps | 99.7% |
| Hodgdon H414 | <<locked>> | 80% | 40,611 psi | 67% | 2438 fps | 97.6% |
| Hodgdon H4350 | <<locked>> | 80% | 37,188 psi | 61% | 2323 fps | 95.1% |
| Hodgdon H4831 SC | <<locked>> | 96% | 47,601 psi | 78% | 2543 fps | 95.5% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 32,387 psi | 53% | 2244 fps | 99.2% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 46,615 psi | 77% | 2507 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 98% | 38,159 psi | 63% | 2500 fps | 95.5% |
| Hodgdon Superformance | 65.4 gr | 80% | 36,303 psi | 60% | 2379 fps | 95.9% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,180 psi | 45% | 1411 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 46,963 psi | 77% | 2464 fps | 100% |
| IMR 3031 | <<locked>> | 80% | 49,023 psi | 80% | 2477 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 43,685 psi | 72% | 2402 fps | 99.9% |
| IMR 4166 Enduron | <<locked>> | 80% | 43,047 psi | 71% | 2379 fps | 98% |
| IMR 4350 | <<locked>> | 80% | 35,534 psi | 58% | 2280 fps | 95.4% |
| IMR 4451 Enduron | <<locked>> | 80% | 41,191 psi | 68% | 2372 fps | 97.5% |
| IMR 4831 | <<locked>> | 80% | 31,067 psi | 51% | 2221 fps | 97.5% |
| IMR 4895 | <<locked>> | 80% | 49,066 psi | 81% | 2533 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 92% | 44,802 psi | 74% | 2461 fps | 95% |
| IMR 7828 SSC | <<locked>> | 94% | 43,482 psi | 71% | 2533 fps | 95.1% |
| Lovex S060 | <<locked>> | 80% | 51,459 psi | 84% | 2484 fps | 100% |
| Lovex S062 | <<locked>> | 80% | 46,978 psi | 77% | 2451 fps | 100% |
| Lovex S065 | <<locked>> | 80% | 38,696 psi | 64% | 2326 fps | 98.2% |
| Lovex S070 | <<locked>> | 80% | 36,854 psi | 61% | 2306 fps | 96.7% |
| Lovex S071 | <<locked>> | 90% | 30,618 psi | 50% | 2215 fps | 95.4% |
| Norma 201 | <<locked>> | 80% | 51,155 psi | 84% | 2500 fps | 100% |
| Norma 202 | <<locked>> | 80% | 51,692 psi | 85% | 2497 fps | 100% |
| Norma 203B | <<locked>> | 80% | 47,239 psi | 78% | 2497 fps | 100% |
| Norma 204 | <<locked>> | 84% | 39,624 psi | 65% | 2402 fps | 95.3% |
| Norma MRP | <<locked>> | 86% | 33,359 psi | 55% | 2359 fps | 95% |
| Norma URP | <<locked>> | 80% | 35,288 psi | 58% | 2326 fps | 98.5% |
| Ramshot Big Game | <<locked>> | 80% | 47,181 psi | 77% | 2516 fps | 100% |
| Ramshot Grand | <<locked>> | 92% | 42,511 psi | 70% | 2523 fps | 95.1% |
| Ramshot Hunter | <<locked>> | 80% | 34,229 psi | 56% | 2316 fps | 96.6% |
| Ramshot Magnum | <<locked>> | 92% | 36,738 psi | 60% | 2395 fps | 95.3% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 27,688 psi | 45% | 1447 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 45,310 psi | 74% | 2451 fps | 98.9% |
| ReloadSwiss RS 52 | <<locked>> | 80% | 51,445 psi | 84% | 2612 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 41,684 psi | 68% | 2500 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 35,027 psi | 57% | 2346 fps | 98.3% |
| ReloadSwiss RS 70 | 62.8 gr | 80% | 34,229 psi | 56% | 2352 fps | 97.7% |
| ReloadSwiss RS 76 | <<locked>> | 96% | 35,302 psi | 58% | 2434 fps | 95.5% |
| Rottweil R 902 | <<locked>> | 80% | 48,820 psi | 80% | 2461 fps | 100% |
| Rottweil R 903 | <<locked>> | 80% | 42,250 psi | 69% | 2408 fps | 100% |
| Rottweil R 904 | <<locked>> | 90% | 43,511 psi | 71% | 2444 fps | 95.3% |
| Rottweil R 905 | <<locked>> | 88% | 37,884 psi | 62% | 2392 fps | 95.3% |
| Rottweil R 907 | <<locked>> | 80% | 39,769 psi | 65% | 2343 fps | 96.7% |
| Shooters World Long Rifle | <<locked>> | 80% | 38,696 psi | 64% | 2326 fps | 98.2% |
| Shooters World Precision | <<locked>> | 80% | 46,978 psi | 77% | 2451 fps | 100% |
| Shooters World SW4350 | <<locked>> | 80% | 36,854 psi | 61% | 2306 fps | 96.7% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 43,294 psi | 71% | 2457 fps | 100% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 50,705 psi | 83% | 2530 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 43,961 psi | 72% | 2320 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 37,855 psi | 62% | 2277 fps | 96.8% |
| SNPE Vectan Tubal 8000 | <<locked>> | 88% | 37,521 psi | 62% | 2388 fps | 95.1% |
| Somchem S335 | <<locked>> | 80% | 51,793 psi | 85% | 2438 fps | 100% |
| Somchem S355 | <<locked>> | 80% | 42,743 psi | 70% | 2408 fps | 100% |
| Somchem S361 | <<locked>> | 92% | 47,427 psi | 78% | 2484 fps | 95.4% |
| Somchem S365 | <<locked>> | 80% | 31,894 psi | 52% | 2290 fps | 99.8% |
| Somchem S385 | <<locked>> | 86% | 36,129 psi | 59% | 2329 fps | 95.6% |
| Unknown powder | <<locked>> | 80% | 38,189 psi | 63% | 2375 fps | 98.6% |
| Vihtavuori N135 | <<locked>> | 80% | 48,965 psi | 80% | 2425 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 49,008 psi | 80% | 2434 fps | 100% |
| Vihtavuori N150 | <<locked>> | 80% | 40,683 psi | 67% | 2343 fps | 100% |
| Vihtavuori N160 | <<locked>> | 80% | 36,767 psi | 60% | 2326 fps | 98.7% |
| Vihtavuori N165 | <<locked>> | 92% | 37,797 psi | 62% | 2356 fps | 95.7% |
| Vihtavuori N540 | <<locked>> | 80% | 47,398 psi | 78% | 2438 fps | 100% |
| Vihtavuori N550 | <<locked>> | 80% | 36,245 psi | 60% | 2329 fps | 98.5% |
| Vihtavuori N555 | <<locked>> | 80% | 27,673 psi | 45% | 2192 fps | 96.8% |
| Vihtavuori N560 | <<locked>> | 94% | 44,077 psi | 72% | 2562 fps | 95% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 35,969 psi | 59% | 2300 fps | 99.8% |
| Winchester 760 | <<locked>> | 80% | 40,611 psi | 67% | 2438 fps | 97.6% |
| Winchester StaBALL HD | <<locked>> | 80% | 22,423 psi | 37% | 2093 fps | 95.1% |
| Winchester Supreme 780 | <<locked>> | 88% | 38,798 psi | 64% | 2379 fps | 95.2% |
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 97 powders for .338 Blaser Mag. loaded with the .338 | 250gr | Nosler Partition RN. Alliant Reloder-26 delivers the highest muzzle velocity at 2,779 fps; across all powders the maximum-charge window runs from 1,578 fps to 2,779 fps. Accurate 3100 gives the best case fill at 100 %, and 97 of the 97 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (420 MPa), the top charges use 60–90 %, leaving at least 10 % headroom. The 250.0 gr projectile in 0.338" calls for a 1:15.5 twist; slower twists will usually not stabilise this weight. Accurate 3100, ADI AR 2213, Alliant Reloder-22 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-26, Hodgdon Superformance rank at the top here: for .338 Blaser Mag. with the .338 | 250gr | Nosler Partition RN 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.