Load Specifications
Load data in caliber .270 Win. with .277 | 140gr | Sierra GameKing 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-17 and ReloadSwiss RS 60.
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 2495 | <<locked>> | 84% | 54,534 psi | 87% | 2759 fps | 100% |
| Accurate 2700 | <<locked>> | 86% | 56,333 psi | 90% | 2825 fps | 98.3% |
| Accurate 3100ᴾ | <<locked>> | 100% | 49,327 psi | 79% | 2799 fps | 98.6% |
| Accurate 4064 | <<locked>> | 86% | 54,810 psi | 88% | 2815 fps | 100% |
| Accurate 4350 | <<locked>> | 94% | 55,288 psi | 89% | 2913 fps | 99.9% |
| ADI AR 2206H | <<locked>> | 82% | 54,157 psi | 87% | 2841 fps | 100% |
| ADI AR 2208 | <<locked>> | 88% | 55,506 psi | 89% | 2848 fps | 100% |
| ADI AR 2209 | <<locked>> | 98% | 52,794 psi | 85% | 2887 fps | 96.9% |
| ADI Benchmark 8208 | <<locked>> | 82% | 56,347 psi | 90% | 2835 fps | 100% |
| Alliant Power Pro 2000-MR | <<locked>> | 84% | 54,114 psi | 87% | 2963 fps | 100% |
| Alliant Reloder- TS 15.5 | <<locked>> | 88% | 55,869 psi | 90% | 2867 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 86% | 56,318 psi | 90% | 2890 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 96% | 55,970 psi | 90% | 2966 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 90% | 53,563 psi | 86% | 2943 fps | 100% |
| Alliant Reloder-19ᴾ | <<locked>> | 100% | 55,637 psi | 89% | 2940 fps | 97.6% |
| Alliant Reloder-22ᴾ | <<locked>> | 100% | 49,110 psi | 79% | 2874 fps | 96.4% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 46,151 psi | 74% | 2818 fps | 100% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 40,596 psi | 65% | 2730 fps | 97.5% |
| Alliant Reloder-26ᴾ | <<locked>> | 100% | 52,808 psi | 85% | 3009 fps | 99.9% |
| Baschieri & Pellagri 107 | <<locked>> | 82% | 53,940 psi | 86% | 2854 fps | 99.9% |
| Bofors RP3 | <<locked>> | 86% | 53,113 psi | 85% | 2831 fps | 100% |
| Bofors RP5ᴾ | <<locked>> | 100% | 49,110 psi | 79% | 2874 fps | 96.4% |
| Bofors RP7 | <<locked>> | 92% | 56,275 psi | 90% | 2864 fps | 98.5% |
| Hodgdon BL-C2 | <<locked>> | 82% | 56,188 psi | 90% | 2867 fps | 100% |
| Hodgdon H380 | <<locked>> | 86% | 53,606 psi | 86% | 2844 fps | 99.7% |
| Hodgdon H414 | <<locked>> | 92% | 53,983 psi | 87% | 2907 fps | 98.7% |
| Hodgdon H4350 | <<locked>> | 90% | 54,186 psi | 87% | 2867 fps | 97.6% |
| Hodgdon H4895 | <<locked>> | 82% | 54,723 psi | 88% | 2848 fps | 100% |
| Hodgdon Hybrid 100V | <<locked>> | 98% | 56,072 psi | 90% | 2887 fps | 100% |
| Hodgdon LEVERevolution | <<locked>> | 84% | 54,926 psi | 88% | 2887 fps | 100% |
| Hodgdon Superformance | <<locked>> | 92% | 54,143 psi | 87% | 2943 fps | 98.5% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 36,230 psi | 58% | 1768 fps | 100% |
| Hodgdon VARGET | <<locked>> | 84% | 55,869 psi | 90% | 2851 fps | 100% |
| IMR 3031 | <<locked>> | 82% | 55,405 psi | 89% | 2831 fps | 100% |
| IMR 4064 | <<locked>> | 86% | 54,940 psi | 88% | 2828 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 84% | 54,201 psi | 87% | 2805 fps | 98.6% |
| IMR 4350 | <<locked>> | 94% | 53,534 psi | 86% | 2841 fps | 98.1% |
| IMR 4451 Enduron | <<locked>> | 90% | 54,491 psi | 87% | 2838 fps | 98.5% |
| IMR 4831 | <<locked>> | 96% | 55,782 psi | 89% | 2904 fps | 100% |
| IMR 4895 | <<locked>> | 84% | 54,273 psi | 87% | 2867 fps | 100% |
| IMR 4955 Enduronᴾ | <<locked>> | 100% | 56,159 psi | 90% | 2881 fps | 95.8% |
| IMR 8208 XBR | <<locked>> | 82% | 56,347 psi | 90% | 2835 fps | 100% |
| Lovex D073.6 | <<locked>> | 82% | 54,302 psi | 87% | 2812 fps | 100% |
| Lovex S060 | <<locked>> | 82% | 53,403 psi | 86% | 2766 fps | 100% |
| Lovex S062 | <<locked>> | 86% | 55,042 psi | 88% | 2825 fps | 100% |
| Lovex S065 | <<locked>> | 92% | 54,288 psi | 87% | 2835 fps | 99.4% |
| Lovex S070 | <<locked>> | 94% | 55,492 psi | 89% | 2874 fps | 98.9% |
| Lovex S071ᴾ | <<locked>> | 100% | 40,814 psi | 65% | 2644 fps | 96.8% |
| Norma 201 | <<locked>> | 84% | 56,333 psi | 90% | 2835 fps | 100% |
| Norma 202 | <<locked>> | 82% | 53,693 psi | 86% | 2785 fps | 100% |
| Norma 203B | <<locked>> | 86% | 55,535 psi | 89% | 2877 fps | 100% |
| Norma 204 | <<locked>> | 94% | 54,056 psi | 87% | 2887 fps | 97.1% |
| Norma MRPᴾ | <<locked>> | 100% | 51,953 psi | 83% | 2956 fps | 98.4% |
| Norma URP | <<locked>> | 94% | 53,998 psi | 87% | 2897 fps | 99.9% |
| Ramshot Big Game | <<locked>> | 86% | 56,130 psi | 90% | 2900 fps | 100% |
| Ramshot Hunter | <<locked>> | 94% | 52,736 psi | 85% | 2894 fps | 99.1% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 36,666 psi | 59% | 1808 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 86% | 53,650 psi | 86% | 2828 fps | 98.9% |
| ReloadSwiss RS 52 | <<locked>> | 82% | 53,316 psi | 85% | 2900 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 88% | 53,127 psi | 85% | 2936 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 94% | 54,940 psi | 88% | 2933 fps | 99.9% |
| ReloadSwiss RS 70 | <<locked>> | 94% | 53,664 psi | 86% | 2959 fps | 99.8% |
| Rottweil R 902 | <<locked>> | 84% | 53,766 psi | 86% | 2789 fps | 100% |
| Rottweil R 903 | <<locked>> | 88% | 53,301 psi | 85% | 2828 fps | 100% |
| Rottweil R 904 | <<locked>> | 98% | 54,795 psi | 88% | 2864 fps | 96.2% |
| Rottweil R 905ᴾ | <<locked>> | 100% | 54,534 psi | 87% | 2920 fps | 97.6% |
| Rottweil R 907 | <<locked>> | 92% | 56,275 psi | 90% | 2864 fps | 98.5% |
| Shooters World Long Rifle | <<locked>> | 92% | 54,288 psi | 87% | 2835 fps | 99.4% |
| Shooters World Match Rifle | <<locked>> | 82% | 54,302 psi | 87% | 2812 fps | 100% |
| Shooters World Precision | <<locked>> | 86% | 55,042 psi | 88% | 2825 fps | 100% |
| Shooters World SW4350 | <<locked>> | 94% | 55,492 psi | 89% | 2874 fps | 98.9% |
| SNPE Vectan SP 11 | <<locked>> | 88% | 54,694 psi | 88% | 2884 fps | 100% |
| SNPE Vectan SP 7 | <<locked>> | 82% | 55,376 psi | 89% | 2844 fps | 99.8% |
| SNPE Vectan SP 9 | <<locked>> | 84% | 56,159 psi | 90% | 2864 fps | 100% |
| SNPE Vectan Tubal 3000 | <<locked>> | 82% | 53,969 psi | 87% | 2720 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 88% | 54,679 psi | 88% | 2723 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 92% | 54,375 psi | 87% | 2789 fps | 98.6% |
| SNPE Vectan Tubal 8000ᴾ | <<locked>> | 100% | 54,041 psi | 87% | 2913 fps | 97.4% |
| Somchem S335 | <<locked>> | 82% | 53,621 psi | 86% | 2717 fps | 100% |
| Somchem S341 | <<locked>> | 82% | 54,897 psi | 88% | 2828 fps | 100% |
| Somchem S355 | <<locked>> | 88% | 53,229 psi | 85% | 2822 fps | 100% |
| Somchem S365 | <<locked>> | 98% | 56,333 psi | 90% | 2949 fps | 100% |
| Somchem S385ᴾ | <<locked>> | 100% | 55,448 psi | 89% | 2900 fps | 98.4% |
| Vihtavuori N133 | <<locked>> | 82% | 54,389 psi | 87% | 2703 fps | 100% |
| Vihtavuori N135 | <<locked>> | 84% | 53,853 psi | 86% | 2749 fps | 100% |
| Vihtavuori N140 | <<locked>> | 84% | 54,056 psi | 87% | 2762 fps | 100% |
| Vihtavuori N150 | <<locked>> | 90% | 54,679 psi | 88% | 2802 fps | 100% |
| Vihtavuori N160 | <<locked>> | 94% | 56,376 psi | 90% | 2894 fps | 99.9% |
| Vihtavuori N165ᴾ | <<locked>> | 100% | 47,819 psi | 77% | 2762 fps | 96.5% |
| Vihtavuori N540 | <<locked>> | 86% | 55,695 psi | 89% | 2808 fps | 100% |
| Vihtavuori N550 | <<locked>> | 94% | 55,259 psi | 89% | 2897 fps | 99.9% |
| Vihtavuori N555ᴾ | <<locked>> | 100% | 51,837 psi | 83% | 2900 fps | 100% |
| Winchester 6.5 StaBALL | <<locked>> | 94% | 56,072 psi | 90% | 2864 fps | 100% |
| Winchester 760 | <<locked>> | 92% | 54,259 psi | 87% | 2913 fps | 98.7% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 41,626 psi | 67% | 2861 fps | 100% |
| Winchester StaBALL Match | <<locked>> | 84% | 56,202 psi | 90% | 2871 fps | 100% |
| Winchester Supreme 780ᴾ | <<locked>> | 100% | 51,750 psi | 83% | 2831 fps | 96.7% |
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 2495 | <<locked>> | 80% | 47,921 psi | 77% | 2667 fps | 100% |
| Accurate 2700 | <<locked>> | 80% | 46,340 psi | 74% | 2657 fps | 96.4% |
| Accurate 3100 | <<locked>> | 92% | 37,507 psi | 60% | 2575 fps | 95.8% |
| Accurate 4064 | <<locked>> | 80% | 45,353 psi | 73% | 2667 fps | 100% |
| Accurate 4350 | <<locked>> | 80% | 34,127 psi | 55% | 2513 fps | 96.5% |
| ADI AR 2206H | <<locked>> | 80% | 50,908 psi | 82% | 2785 fps | 100% |
| ADI AR 2208 | <<locked>> | 80% | 43,294 psi | 69% | 2638 fps | 99.1% |
| ADI AR 2209 | <<locked>> | 94% | 46,456 psi | 74% | 2776 fps | 95.3% |
| ADI Benchmark 8208 | <<locked>> | 80% | 52,982 psi | 85% | 2785 fps | 100% |
| Alliant Power Pro 2000-MR | <<locked>> | 80% | 47,050 psi | 75% | 2841 fps | 99.7% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 43,540 psi | 70% | 2664 fps | 99.9% |
| Alliant Reloder-15 | <<locked>> | 80% | 46,470 psi | 75% | 2730 fps | 99.6% |
| Alliant Reloder-16 | <<locked>> | 80% | 33,721 psi | 54% | 2523 fps | 96.5% |
| Alliant Reloder-17 | 47.2 gr | 80% | 37,913 psi | 61% | 2651 fps | 99.2% |
| Alliant Reloder-19 | <<locked>> | 94% | 45,832 psi | 73% | 2766 fps | 95.4% |
| Alliant Reloder-22 | <<locked>> | 98% | 45,774 psi | 73% | 2812 fps | 95.5% |
| Alliant Reloder-23 | <<locked>> | 84% | 27,847 psi | 45% | 2382 fps | 95.5% |
| Alliant Reloder-25 | <<locked>> | 96% | 35,708 psi | 57% | 2608 fps | 95.5% |
| Alliant Reloder-26 | <<locked>> | 88% | 34,200 psi | 55% | 2618 fps | 96% |
| Baschieri & Pellagri 107 | <<locked>> | 80% | 50,444 psi | 81% | 2799 fps | 99.7% |
| Bofors RP3 | <<locked>> | 80% | 43,555 psi | 70% | 2674 fps | 99.9% |
| Bofors RP5 | <<locked>> | 98% | 45,774 psi | 73% | 2812 fps | 95.5% |
| Bofors RP7 | <<locked>> | 82% | 41,263 psi | 66% | 2592 fps | 95.2% |
| Hodgdon BL-C2 | <<locked>> | 80% | 52,533 psi | 84% | 2812 fps | 100% |
| Hodgdon H380 | <<locked>> | 80% | 44,106 psi | 71% | 2680 fps | 98.6% |
| Hodgdon H414 | <<locked>> | 82% | 38,653 psi | 62% | 2615 fps | 95% |
| Hodgdon H4350 | <<locked>> | 84% | 44,773 psi | 72% | 2700 fps | 95.4% |
| Hodgdon H4895 | <<locked>> | 80% | 51,430 psi | 82% | 2795 fps | 100% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 31,154 psi | 50% | 2421 fps | 97.3% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 47,892 psi | 77% | 2776 fps | 100% |
| Hodgdon Superformance | <<locked>> | 84% | 40,596 psi | 65% | 2687 fps | 95.1% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,035 psi | 43% | 1581 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 49,356 psi | 79% | 2749 fps | 100% |
| IMR 3031 | <<locked>> | 80% | 51,880 psi | 83% | 2782 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 45,513 psi | 73% | 2674 fps | 99.5% |
| IMR 4166 Enduron | <<locked>> | 80% | 47,718 psi | 77% | 2697 fps | 97.5% |
| IMR 4350 | <<locked>> | 86% | 41,640 psi | 67% | 2625 fps | 95.3% |
| IMR 4451 Enduron | <<locked>> | 80% | 40,161 psi | 64% | 2572 fps | 95.3% |
| IMR 4831 | <<locked>> | 80% | 32,982 psi | 53% | 2470 fps | 96.1% |
| IMR 4895 | <<locked>> | 80% | 47,645 psi | 76% | 2759 fps | 99.9% |
| IMR 4955 Enduron | <<locked>> | 98% | 52,518 psi | 84% | 2818 fps | 95% |
| IMR 8208 XBR | <<locked>> | 80% | 52,982 psi | 85% | 2785 fps | 100% |
| Lovex D073.6 | <<locked>> | 80% | 50,981 psi | 82% | 2766 fps | 100% |
| Lovex S060 | <<locked>> | 80% | 50,241 psi | 81% | 2717 fps | 100% |
| Lovex S062 | <<locked>> | 80% | 45,672 psi | 73% | 2674 fps | 100% |
| Lovex S065 | <<locked>> | 80% | 37,565 psi | 60% | 2520 fps | 96.2% |
| Lovex S070 | <<locked>> | 82% | 38,101 psi | 61% | 2549 fps | 95.1% |
| Lovex S071 | <<locked>> | 96% | 35,955 psi | 58% | 2539 fps | 95.2% |
| Norma 201 | <<locked>> | 80% | 49,763 psi | 80% | 2733 fps | 100% |
| Norma 202 | <<locked>> | 80% | 50,444 psi | 81% | 2736 fps | 100% |
| Norma 203B | <<locked>> | 80% | 45,832 psi | 73% | 2717 fps | 99.8% |
| Norma 204 | <<locked>> | 90% | 47,268 psi | 76% | 2772 fps | 95.5% |
| Norma MRP | <<locked>> | 92% | 39,450 psi | 63% | 2710 fps | 95% |
| Norma URP | <<locked>> | 80% | 34,156 psi | 55% | 2510 fps | 96.3% |
| Ramshot Big Game | <<locked>> | 80% | 45,788 psi | 73% | 2733 fps | 99.7% |
| Ramshot Hunter | <<locked>> | 84% | 37,898 psi | 61% | 2608 fps | 95.8% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 27,499 psi | 44% | 1621 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 44,193 psi | 71% | 2661 fps | 97.3% |
| ReloadSwiss RS 52 | <<locked>> | 80% | 49,995 psi | 80% | 2844 fps | 99.9% |
| ReloadSwiss RS 60 | 47.2 gr | 80% | 40,292 psi | 65% | 2710 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 33,852 psi | 54% | 2530 fps | 96% |
| ReloadSwiss RS 70 | 49.1 gr | 82% | 35,534 psi | 57% | 2589 fps | 95.9% |
| Rottweil R 902 | <<locked>> | 80% | 47,500 psi | 76% | 2687 fps | 100% |
| Rottweil R 903 | <<locked>> | 80% | 40,988 psi | 66% | 2618 fps | 99.6% |
| Rottweil R 904 | <<locked>> | 96% | 51,169 psi | 82% | 2805 fps | 95.3% |
| Rottweil R 905 | <<locked>> | 94% | 44,773 psi | 72% | 2749 fps | 95.3% |
| Rottweil R 907 | <<locked>> | 82% | 41,263 psi | 66% | 2592 fps | 95.2% |
| Shooters World Long Rifle | <<locked>> | 80% | 37,565 psi | 60% | 2520 fps | 96.2% |
| Shooters World Match Rifle | <<locked>> | 80% | 50,981 psi | 82% | 2766 fps | 100% |
| Shooters World Precision | <<locked>> | 80% | 45,672 psi | 73% | 2674 fps | 100% |
| Shooters World SW4350 | <<locked>> | 82% | 38,101 psi | 61% | 2549 fps | 95.1% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 42,076 psi | 67% | 2671 fps | 99.3% |
| SNPE Vectan SP 7 | <<locked>> | 80% | 51,750 psi | 83% | 2785 fps | 99.5% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 49,458 psi | 79% | 2759 fps | 99.9% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 50,908 psi | 82% | 2674 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 42,844 psi | 69% | 2543 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 82% | 39,204 psi | 63% | 2516 fps | 95.3% |
| SNPE Vectan Tubal 8000 | <<locked>> | 94% | 44,353 psi | 71% | 2743 fps | 95.1% |
| Somchem S335 | <<locked>> | 80% | 50,444 psi | 81% | 2674 fps | 100% |
| Somchem S341 | <<locked>> | 80% | 51,300 psi | 82% | 2776 fps | 100% |
| Somchem S355 | <<locked>> | 80% | 41,437 psi | 66% | 2618 fps | 99.5% |
| Somchem S365 | <<locked>> | 80% | 30,792 psi | 49% | 2470 fps | 98.5% |
| Somchem S385 | <<locked>> | 92% | 42,540 psi | 68% | 2674 fps | 95.6% |
| Vihtavuori N133 | <<locked>> | 80% | 51,401 psi | 82% | 2661 fps | 100% |
| Vihtavuori N135 | <<locked>> | 80% | 47,558 psi | 76% | 2657 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 47,747 psi | 77% | 2671 fps | 100% |
| Vihtavuori N150 | <<locked>> | 80% | 39,537 psi | 63% | 2549 fps | 99.8% |
| Vihtavuori N160 | <<locked>> | 80% | 35,549 psi | 57% | 2513 fps | 96.8% |
| Vihtavuori N165 | <<locked>> | 98% | 44,570 psi | 71% | 2700 fps | 95.7% |
| Vihtavuori N540 | <<locked>> | 80% | 46,122 psi | 74% | 2661 fps | 100% |
| Vihtavuori N550 | <<locked>> | 80% | 35,114 psi | 56% | 2516 fps | 96.4% |
| Vihtavuori N555 | <<locked>> | 84% | 30,400 psi | 49% | 2461 fps | 95.7% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 34,882 psi | 56% | 2487 fps | 98.6% |
| Winchester 760 | <<locked>> | 82% | 38,856 psi | 62% | 2621 fps | 95.1% |
| Winchester StaBALL HD | <<locked>> | 88% | 27,978 psi | 45% | 2467 fps | 96.3% |
| Winchester StaBALL Match | <<locked>> | 80% | 49,385 psi | 79% | 2766 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 96% | 45,063 psi | 72% | 2713 fps | 95% |
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 .270 Win. loaded with the .277 | 140gr | Sierra GameKing. Alliant Reloder-26 delivers the highest muzzle velocity at 3,009 fps; across all powders the maximum-charge window runs from 1,768 fps to 3,009 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 (430 MPa), the top charges use 58–90 %, leaving at least 10 % headroom. The 140.0 gr projectile in 0.277" calls for a 1:11.5 twist; slower twists will usually not stabilise this weight. Accurate 3100, Alliant Reloder-19, 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-17, ReloadSwiss RS 60 rank at the top here: for .270 Win. with the .277 | 140gr | Sierra GameKing 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.