Load Specifications
Load data in caliber .338 Rem. Ultra Mag. with .338 | 165gr | TPM XTLD bullet and 97 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Alliant Reloder-16, ReloadSwiss RS 70 and Ramshot Hunter.
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 2015 | <<locked>> | 82% | 57,159 psi | 90% | 3009 fps | 100% |
| Accurate 2495 | <<locked>> | 86% | 57,188 psi | 90% | 3035 fps | 100% |
| Accurate 2700 | <<locked>> | 86% | 55,492 psi | 87% | 3028 fps | 97.3% |
| Accurate 3100ᴾ | <<locked>> | 100% | 48,834 psi | 77% | 2989 fps | 97.8% |
| Accurate 4064 | <<locked>> | 88% | 57,348 psi | 90% | 3084 fps | 100% |
| Accurate 4350 | <<locked>> | 94% | 54,389 psi | 85% | 3117 fps | 99.6% |
| ADI AR 2206H | <<locked>> | 84% | 56,739 psi | 89% | 3117 fps | 100% |
| ADI AR 2208 | <<locked>> | 88% | 54,447 psi | 85% | 3064 fps | 99.8% |
| ADI AR 2209ᴾ | <<locked>> | 100% | 56,086 psi | 88% | 3150 fps | 96.6% |
| ADI Benchmark 8208 | <<locked>> | 82% | 55,288 psi | 87% | 3064 fps | 100% |
| Alliant AR-Comp | <<locked>> | 82% | 56,855 psi | 89% | 3041 fps | 100% |
| Alliant Power Pro 2000-MR | <<locked>> | 86% | 57,290 psi | 90% | 3241 fps | 100% |
| Alliant Reloder- TS 15.5 | <<locked>> | 88% | 55,042 psi | 86% | 3087 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 86% | 55,201 psi | 87% | 3107 fps | 99.9% |
| Alliant Reloder-16 | <<locked>> | 96% | 55,274 psi | 87% | 3182 fps | 99.9% |
| Alliant Reloder-17 | <<locked>> | 92% | 56,695 psi | 89% | 3212 fps | 100% |
| Alliant Reloder-19ᴾ | <<locked>> | 100% | 55,129 psi | 86% | 3136 fps | 96.6% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 45,818 psi | 72% | 3015 fps | 99.8% |
| Alliant Reloder-26ᴾ | <<locked>> | 100% | 52,649 psi | 83% | 3202 fps | 99.6% |
| Baschieri & Pellagri 107 | <<locked>> | 84% | 56,971 psi | 89% | 3127 fps | 99.8% |
| Bofors RP3 | <<locked>> | 88% | 55,912 psi | 88% | 3104 fps | 100% |
| Bofors RP7 | <<locked>> | 92% | 55,521 psi | 87% | 3071 fps | 97.5% |
| Hodgdon Benchmark | <<locked>> | 82% | 56,753 psi | 89% | 3045 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 82% | 55,463 psi | 87% | 3091 fps | 100% |
| Hodgdon H380 | <<locked>> | 88% | 56,594 psi | 89% | 3117 fps | 99.5% |
| Hodgdon H414 | <<locked>> | 94% | 57,058 psi | 89% | 3169 fps | 98.4% |
| Hodgdon H4350 | <<locked>> | 92% | 56,927 psi | 89% | 3130 fps | 97.1% |
| Hodgdon H4895 | <<locked>> | 84% | 57,363 psi | 90% | 3130 fps | 100% |
| Hodgdon Hybrid 100V | <<locked>> | 98% | 55,550 psi | 87% | 3100 fps | 100% |
| Hodgdon LEVERevolution | <<locked>> | 86% | 57,725 psi | 90% | 3159 fps | 100% |
| Hodgdon Superformance | <<locked>> | 92% | 53,693 psi | 84% | 3136 fps | 97.6% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 35,766 psi | 56% | 1985 fps | 100% |
| Hodgdon VARGET | <<locked>> | 84% | 54,824 psi | 86% | 3074 fps | 100% |
| IMR 3031 | <<locked>> | 82% | 54,012 psi | 85% | 3061 fps | 100% |
| IMR 4064 | <<locked>> | 88% | 57,363 psi | 90% | 3100 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 86% | 56,884 psi | 89% | 3077 fps | 98.2% |
| IMR 4350 | <<locked>> | 96% | 56,376 psi | 88% | 3097 fps | 97.7% |
| IMR 4451 Enduron | <<locked>> | 92% | 57,363 psi | 90% | 3104 fps | 98.2% |
| IMR 4831 | <<locked>> | 96% | 55,013 psi | 86% | 3110 fps | 99.7% |
| IMR 4895 | <<locked>> | 86% | 56,637 psi | 89% | 3140 fps | 100% |
| IMR 8208 XBR | <<locked>> | 82% | 55,288 psi | 87% | 3064 fps | 100% |
| Lovex D073.6 | <<locked>> | 84% | 57,029 psi | 89% | 3087 fps | 100% |
| Lovex S060 | <<locked>> | 84% | 55,709 psi | 87% | 3041 fps | 100% |
| Lovex S062 | <<locked>> | 88% | 57,479 psi | 90% | 3094 fps | 100% |
| Lovex S065 | <<locked>> | 94% | 57,029 psi | 89% | 3097 fps | 99.2% |
| Lovex S070 | <<locked>> | 94% | 54,911 psi | 86% | 3081 fps | 98.1% |
| Norma 201 | <<locked>> | 84% | 55,361 psi | 87% | 3061 fps | 100% |
| Norma 202 | <<locked>> | 84% | 55,999 psi | 88% | 3058 fps | 100% |
| Norma 203B | <<locked>> | 86% | 54,476 psi | 85% | 3094 fps | 99.9% |
| Norma 204 | <<locked>> | 96% | 57,493 psi | 90% | 3150 fps | 96.8% |
| Norma MRPᴾ | <<locked>> | 100% | 51,735 psi | 81% | 3153 fps | 97.5% |
| Norma URP | <<locked>> | 96% | 56,913 psi | 89% | 3159 fps | 99.8% |
| Ramshot Big Game | <<locked>> | 86% | 55,419 psi | 87% | 3117 fps | 100% |
| Ramshot Hunter | <<locked>> | 96% | 55,999 psi | 88% | 3156 fps | 98.9% |
| Ramshot TAC | <<locked>> | 82% | 55,825 psi | 87% | 3077 fps | 99.1% |
| Ramshot Wild Boar | <<locked>> | 82% | 55,651 psi | 87% | 3097 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 36,318 psi | 57% | 2031 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 88% | 56,724 psi | 89% | 3094 fps | 98.7% |
| ReloadSwiss RS 52 | <<locked>> | 84% | 56,057 psi | 88% | 3179 fps | 99.9% |
| ReloadSwiss RS 60 | <<locked>> | 90% | 56,260 psi | 88% | 3209 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 94% | 54,476 psi | 85% | 3136 fps | 99.5% |
| ReloadSwiss RS 70 | <<locked>> | 96% | 57,377 psi | 90% | 3228 fps | 99.7% |
| Rottweil R 901 | <<locked>> | 82% | 56,159 psi | 88% | 3045 fps | 100% |
| Rottweil R 902 | <<locked>> | 86% | 56,028 psi | 88% | 3061 fps | 100% |
| Rottweil R 903 | <<locked>> | 90% | 55,738 psi | 87% | 3094 fps | 100% |
| Rottweil R 905ᴾ | <<locked>> | 100% | 54,157 psi | 85% | 3120 fps | 96.5% |
| Rottweil R 907 | <<locked>> | 92% | 55,521 psi | 87% | 3071 fps | 97.5% |
| Shooters World Long Rifle | <<locked>> | 94% | 57,029 psi | 89% | 3097 fps | 99.2% |
| Shooters World Match Rifle | <<locked>> | 84% | 57,029 psi | 89% | 3087 fps | 100% |
| Shooters World Precision | <<locked>> | 88% | 57,479 psi | 90% | 3094 fps | 100% |
| Shooters World SW4350 | <<locked>> | 94% | 54,911 psi | 86% | 3081 fps | 98.1% |
| SNPE Vectan SP 11 | <<locked>> | 90% | 57,595 psi | 90% | 3153 fps | 100% |
| SNPE Vectan SP 7 | <<locked>> | 82% | 54,549 psi | 85% | 3058 fps | 99.3% |
| SNPE Vectan SP 9 | <<locked>> | 84% | 55,216 psi | 87% | 3081 fps | 100% |
| SNPE Vectan Tubal 3000 | <<locked>> | 84% | 56,420 psi | 88% | 2995 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 90% | 57,203 psi | 90% | 2989 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 94% | 57,305 psi | 90% | 3048 fps | 98.3% |
| SNPE Vectan Tubal 8000ᴾ | <<locked>> | 100% | 53,664 psi | 84% | 3114 fps | 96.4% |
| Somchem S335 | <<locked>> | 84% | 56,014 psi | 88% | 2989 fps | 100% |
| Somchem S341 | <<locked>> | 82% | 54,128 psi | 85% | 3045 fps | 99.9% |
| Somchem S355 | <<locked>> | 90% | 55,825 psi | 87% | 3094 fps | 100% |
| Somchem S365 | <<locked>> | 98% | 55,738 psi | 87% | 3159 fps | 100% |
| Somchem S385ᴾ | <<locked>> | 100% | 55,013 psi | 86% | 3094 fps | 97.5% |
| Vihtavuori N133 | <<locked>> | 84% | 56,797 psi | 89% | 2979 fps | 100% |
| Vihtavuori N135 | <<locked>> | 86% | 55,999 psi | 88% | 3022 fps | 100% |
| Vihtavuori N140 | <<locked>> | 86% | 56,782 psi | 89% | 3035 fps | 100% |
| Vihtavuori N150 | <<locked>> | 92% | 57,522 psi | 90% | 3068 fps | 100% |
| Vihtavuori N160 | <<locked>> | 94% | 55,535 psi | 87% | 3100 fps | 99.6% |
| Vihtavuori N530 | <<locked>> | 82% | 55,956 psi | 88% | 3061 fps | 100% |
| Vihtavuori N540 | <<locked>> | 86% | 55,114 psi | 86% | 3028 fps | 100% |
| Vihtavuori N550 | <<locked>> | 94% | 54,781 psi | 86% | 3104 fps | 99.5% |
| Vihtavuori N555ᴾ | <<locked>> | 100% | 51,169 psi | 80% | 3097 fps | 99.7% |
| Winchester 6.5 StaBALL | <<locked>> | 94% | 55,782 psi | 87% | 3068 fps | 100% |
| Winchester 748 | <<locked>> | 82% | 56,478 psi | 89% | 3110 fps | 100% |
| Winchester 760 | <<locked>> | 94% | 57,246 psi | 90% | 3173 fps | 98.4% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 41,394 psi | 65% | 3041 fps | 99.9% |
| Winchester StaBALL Match | <<locked>> | 84% | 55,376 psi | 87% | 3087 fps | 100% |
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 2015 | <<locked>> | 80% | 53,766 psi | 84% | 2963 fps | 100% |
| Accurate 2495 | <<locked>> | 80% | 46,876 psi | 73% | 2887 fps | 100% |
| Accurate 2700 | <<locked>> | 82% | 48,428 psi | 76% | 2907 fps | 95.7% |
| Accurate 3100 | <<locked>> | 94% | 39,407 psi | 62% | 2805 fps | 95.2% |
| Accurate 4064 | <<locked>> | 80% | 44,266 psi | 69% | 2881 fps | 100% |
| Accurate 4350 | <<locked>> | 82% | 35,505 psi | 56% | 2746 fps | 95.6% |
| ADI AR 2206H | <<locked>> | 80% | 49,864 psi | 78% | 3005 fps | 99.7% |
| ADI AR 2208 | <<locked>> | 80% | 42,264 psi | 66% | 2841 fps | 98.1% |
| ADI AR 2209 | <<locked>> | 98% | 52,344 psi | 82% | 3087 fps | 95.7% |
| ADI Benchmark 8208 | <<locked>> | 80% | 51,967 psi | 81% | 3009 fps | 100% |
| Alliant AR-Comp | <<locked>> | 80% | 53,156 psi | 83% | 2992 fps | 100% |
| Alliant Power Pro 2000-MR | <<locked>> | 80% | 46,151 psi | 72% | 3045 fps | 98.9% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 42,438 psi | 67% | 2867 fps | 99.3% |
| Alliant Reloder-15 | <<locked>> | 80% | 45,469 psi | 71% | 2940 fps | 98.9% |
| Alliant Reloder-16 | 73.8 gr | 82% | 35,114 psi | 55% | 2762 fps | 95.6% |
| Alliant Reloder-17 | <<locked>> | 80% | 37,072 psi | 58% | 2838 fps | 98.1% |
| Alliant Reloder-19 | <<locked>> | 98% | 51,517 psi | 81% | 3074 fps | 95.7% |
| Alliant Reloder-23 | <<locked>> | 88% | 30,937 psi | 48% | 2661 fps | 95.6% |
| Alliant Reloder-26 | <<locked>> | 90% | 36,303 psi | 57% | 2854 fps | 95.4% |
| Baschieri & Pellagri 107 | <<locked>> | 80% | 49,647 psi | 78% | 3009 fps | 99.2% |
| Bofors RP3 | <<locked>> | 80% | 42,525 psi | 67% | 2874 fps | 99.4% |
| Bofors RP7 | <<locked>> | 86% | 45,905 psi | 72% | 2897 fps | 95.2% |
| Hodgdon Benchmark | <<locked>> | 80% | 53,374 psi | 84% | 2995 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 80% | 51,677 psi | 81% | 3031 fps | 100% |
| Hodgdon H380 | <<locked>> | 80% | 43,149 psi | 68% | 2877 fps | 97.4% |
| Hodgdon H414 | <<locked>> | 86% | 43,395 psi | 68% | 2923 fps | 95.2% |
| Hodgdon H4350 | <<locked>> | 88% | 50,009 psi | 78% | 3012 fps | 95.6% |
| Hodgdon H4895 | <<locked>> | 80% | 50,401 psi | 79% | 3015 fps | 99.9% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 30,342 psi | 48% | 2595 fps | 95.4% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 46,891 psi | 73% | 2986 fps | 99.8% |
| Hodgdon Superformance | <<locked>> | 88% | 46,311 psi | 73% | 3002 fps | 95.7% |
| Hodgdon TrailBoss | <<locked>> | 80% | 26,672 psi | 42% | 1781 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 48,327 psi | 76% | 2963 fps | 99.7% |
| IMR 3031 | <<locked>> | 80% | 50,517 psi | 79% | 3009 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 44,411 psi | 70% | 2881 fps | 98.7% |
| IMR 4166 Enduron | <<locked>> | 80% | 46,891 psi | 73% | 2900 fps | 96.1% |
| IMR 4350 | <<locked>> | 90% | 46,528 psi | 73% | 2927 fps | 95.5% |
| IMR 4451 Enduron | <<locked>> | 84% | 44,585 psi | 70% | 2877 fps | 95.4% |
| IMR 4831 | <<locked>> | 82% | 34,272 psi | 54% | 2700 fps | 95.2% |
| IMR 4895 | <<locked>> | 80% | 46,615 psi | 73% | 2969 fps | 99.4% |
| IMR 8208 XBR | <<locked>> | 80% | 51,967 psi | 81% | 3009 fps | 100% |
| Lovex D073.6 | <<locked>> | 80% | 49,748 psi | 78% | 2979 fps | 100% |
| Lovex S060 | <<locked>> | 80% | 49,197 psi | 77% | 2933 fps | 99.6% |
| Lovex S062 | <<locked>> | 80% | 44,585 psi | 70% | 2884 fps | 99.7% |
| Lovex S065 | <<locked>> | 82% | 39,131 psi | 61% | 2766 fps | 95.3% |
| Lovex S070 | <<locked>> | 86% | 42,525 psi | 67% | 2851 fps | 95.2% |
| Norma 201 | <<locked>> | 80% | 48,776 psi | 76% | 2953 fps | 100% |
| Norma 202 | <<locked>> | 80% | 49,313 psi | 77% | 2956 fps | 100% |
| Norma 203B | <<locked>> | 80% | 44,831 psi | 70% | 2923 fps | 99.1% |
| Norma 204 | <<locked>> | 92% | 49,850 psi | 78% | 3022 fps | 95% |
| Norma MRP | <<locked>> | 96% | 44,802 psi | 70% | 3018 fps | 95.6% |
| Norma URP | <<locked>> | 82% | 35,578 psi | 56% | 2749 fps | 95.5% |
| Ramshot Big Game | <<locked>> | 80% | 44,933 psi | 70% | 2936 fps | 99.1% |
| Ramshot Hunter | 82 gr | 86% | 39,711 psi | 62% | 2848 fps | 95% |
| Ramshot TAC | <<locked>> | 80% | 52,228 psi | 82% | 3018 fps | 98.6% |
| Ramshot Wild Boar | <<locked>> | 80% | 52,112 psi | 82% | 3038 fps | 99.8% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 27,079 psi | 42% | 1824 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 43,381 psi | 68% | 2858 fps | 95.9% |
| ReloadSwiss RS 52 | <<locked>> | 80% | 48,660 psi | 76% | 3054 fps | 99.3% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 39,407 psi | 62% | 2910 fps | 99.9% |
| ReloadSwiss RS 62 | <<locked>> | 82% | 35,418 psi | 56% | 2762 fps | 95.2% |
| ReloadSwiss RS 70 | 82.6 gr | 84% | 37,420 psi | 59% | 2828 fps | 95.2% |
| Rottweil R 901 | <<locked>> | 80% | 52,765 psi | 83% | 2995 fps | 100% |
| Rottweil R 902 | <<locked>> | 80% | 46,296 psi | 73% | 2900 fps | 99.8% |
| Rottweil R 903 | <<locked>> | 80% | 39,972 psi | 63% | 2812 fps | 98.7% |
| Rottweil R 905 | <<locked>> | 98% | 50,444 psi | 79% | 3054 fps | 95.6% |
| Rottweil R 907 | <<locked>> | 86% | 45,905 psi | 72% | 2897 fps | 95.2% |
| Shooters World Long Rifle | <<locked>> | 82% | 39,131 psi | 61% | 2766 fps | 95.3% |
| Shooters World Match Rifle | <<locked>> | 80% | 49,748 psi | 78% | 2979 fps | 100% |
| Shooters World Precision | <<locked>> | 80% | 44,585 psi | 70% | 2884 fps | 99.7% |
| Shooters World SW4350 | <<locked>> | 86% | 42,525 psi | 67% | 2851 fps | 95.2% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 41,060 psi | 64% | 2864 fps | 98.4% |
| SNPE Vectan SP 7 | <<locked>> | 80% | 50,836 psi | 80% | 2995 fps | 98.8% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 48,443 psi | 76% | 2969 fps | 99.5% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 49,748 psi | 78% | 2897 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 41,771 psi | 65% | 2753 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 86% | 43,947 psi | 69% | 2818 fps | 95.4% |
| SNPE Vectan Tubal 8000 | <<locked>> | 98% | 49,966 psi | 78% | 3048 fps | 95.5% |
| Somchem S335 | <<locked>> | 80% | 49,545 psi | 78% | 2894 fps | 100% |
| Somchem S341 | <<locked>> | 80% | 50,488 psi | 79% | 2986 fps | 99.7% |
| Somchem S355 | <<locked>> | 80% | 40,524 psi | 64% | 2818 fps | 98.7% |
| Somchem S365 | <<locked>> | 80% | 29,849 psi | 47% | 2638 fps | 96.8% |
| Somchem S385 | <<locked>> | 94% | 44,918 psi | 70% | 2917 fps | 95% |
| Vihtavuori N133 | <<locked>> | 80% | 50,183 psi | 79% | 2887 fps | 100% |
| Vihtavuori N135 | <<locked>> | 80% | 46,253 psi | 72% | 2877 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 46,731 psi | 73% | 2887 fps | 100% |
| Vihtavuori N150 | <<locked>> | 80% | 38,638 psi | 61% | 2746 fps | 99.3% |
| Vihtavuori N160 | <<locked>> | 80% | 34,592 psi | 54% | 2694 fps | 95% |
| Vihtavuori N530 | <<locked>> | 80% | 52,301 psi | 82% | 3009 fps | 100% |
| Vihtavuori N540 | <<locked>> | 80% | 45,237 psi | 71% | 2874 fps | 100% |
| Vihtavuori N550 | <<locked>> | 82% | 36,666 psi | 57% | 2753 fps | 95.6% |
| Vihtavuori N555 | <<locked>> | 88% | 33,924 psi | 53% | 2743 fps | 95.7% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 34,272 psi | 54% | 2664 fps | 97.4% |
| Winchester 748 | <<locked>> | 80% | 52,591 psi | 82% | 3054 fps | 100% |
| Winchester 760 | <<locked>> | 86% | 43,555 psi | 68% | 2927 fps | 95.3% |
| Winchester StaBALL HD | <<locked>> | 90% | 29,385 psi | 46% | 2680 fps | 95.3% |
| Winchester StaBALL Match | <<locked>> | 80% | 48,269 psi | 76% | 2972 fps | 99.8% |
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 Rem. Ultra Mag. loaded with the .338 | 165gr | TPM XTLD. Alliant Power Pro 2000-MR delivers the highest muzzle velocity at 3,241 fps; across all powders the maximum-charge window runs from 1,985 fps to 3,241 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 (440 MPa), the top charges use 56–90 %, leaving at least 10 % headroom. The 165.0 gr projectile in 0.338" calls for a 1:14.5 twist; slower twists will usually not stabilise this weight. Accurate 3100, ADI AR 2209, Alliant Reloder-19 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. Alliant Reloder-16, ReloadSwiss RS 70, Ramshot Hunter rank at the top here: for .338 Rem. Ultra Mag. with the .338 | 165gr | TPM XTLD 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.