Load Specifications
Load data in caliber .280 Ackley Improved with .284 | 160gr | Woodleigh PP SN bullet and 98 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Alliant Reloder-26, ReloadSwiss RS 70 and Alliant Reloder-17.
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>> | 82% | 56,695 psi | 87% | 2680 fps | 100% |
| Accurate 2700 | <<locked>> | 84% | 57,609 psi | 89% | 2756 fps | 99.3% |
| Accurate 3100ᴾ | <<locked>> | 100% | 56,043 psi | 86% | 2805 fps | 99.9% |
| Accurate 4064 | <<locked>> | 84% | 57,159 psi | 88% | 2736 fps | 100% |
| Accurate 4350 | <<locked>> | 92% | 58,175 psi | 89% | 2851 fps | 100% |
| Accurate MAGPROᴾ | <<locked>> | 100% | 58,204 psi | 90% | 2949 fps | 97.2% |
| ADI AR 2208 | <<locked>> | 86% | 56,971 psi | 88% | 2769 fps | 100% |
| ADI AR 2209 | <<locked>> | 96% | 55,187 psi | 85% | 2841 fps | 98.6% |
| ADI AR 2213ᴾ | <<locked>> | 100% | 56,434 psi | 87% | 2890 fps | 97.8% |
| Alliant Power Pro 2000-MR | <<locked>> | 82% | 56,710 psi | 87% | 2894 fps | 100% |
| Alliant Power Pro Varmint | <<locked>> | 96% | 55,259 psi | 85% | 2838 fps | 98.6% |
| Alliant Power Pro Varmint | <<locked>> | 96% | 55,259 psi | 85% | 2838 fps | 98.6% |
| Alliant Reloder- TS 15.5 | <<locked>> | 86% | 57,957 psi | 89% | 2792 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 84% | 58,102 psi | 89% | 2815 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 94% | 58,697 psi | 90% | 2900 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 88% | 56,492 psi | 87% | 2874 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 98% | 58,030 psi | 89% | 2881 fps | 99% |
| Alliant Reloder-22ᴾ | <<locked>> | 100% | 55,506 psi | 85% | 2887 fps | 98.8% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 52,460 psi | 81% | 2815 fps | 100% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 45,585 psi | 70% | 2749 fps | 99.6% |
| Alliant Reloder-26 | <<locked>> | 98% | 56,492 psi | 87% | 2959 fps | 100% |
| Bofors RP15ᴾ | <<locked>> | 100% | 50,923 psi | 78% | 2812 fps | 98% |
| Bofors RP3 | <<locked>> | 84% | 55,361 psi | 85% | 2759 fps | 100% |
| Bofors RP5ᴾ | <<locked>> | 100% | 55,506 psi | 85% | 2887 fps | 98.8% |
| Bofors RP7 | <<locked>> | 90% | 58,175 psi | 89% | 2802 fps | 99.5% |
| Hodgdon H380 | <<locked>> | 84% | 55,477 psi | 85% | 2776 fps | 100% |
| Hodgdon H414 | <<locked>> | 90% | 56,463 psi | 87% | 2848 fps | 99.6% |
| Hodgdon H4350 | <<locked>> | 88% | 55,999 psi | 86% | 2805 fps | 98.9% |
| Hodgdon H4831 | <<locked>> | 98% | 56,724 psi | 87% | 2838 fps | 97.2% |
| Hodgdon H4831 SC | <<locked>> | 98% | 55,492 psi | 85% | 2818 fps | 96.9% |
| Hodgdon Hybrid 100V | <<locked>> | 94% | 55,347 psi | 85% | 2772 fps | 100% |
| Hodgdon LEVERevolution | <<locked>> | 82% | 56,797 psi | 87% | 2805 fps | 100% |
| Hodgdon Retumboᴾ | <<locked>> | 100% | 44,701 psi | 69% | 2785 fps | 97.4% |
| Hodgdon Superformance | <<locked>> | 90% | 56,681 psi | 87% | 2884 fps | 99.5% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 36,463 psi | 56% | 1716 fps | 100% |
| Hodgdon VARGET | <<locked>> | 82% | 57,276 psi | 88% | 2769 fps | 100% |
| IMR 4064 | <<locked>> | 84% | 56,376 psi | 87% | 2749 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 82% | 55,448 psi | 85% | 2736 fps | 99.5% |
| IMR 4350 | <<locked>> | 92% | 55,608 psi | 86% | 2782 fps | 99.3% |
| IMR 4451 Enduron | <<locked>> | 88% | 56,115 psi | 86% | 2772 fps | 99.5% |
| IMR 4831 | <<locked>> | 94% | 58,276 psi | 90% | 2838 fps | 100% |
| IMR 4895 | <<locked>> | 82% | 56,028 psi | 86% | 2789 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 98% | 58,073 psi | 89% | 2825 fps | 97.6% |
| IMR 7828 SSCᴾ | <<locked>> | 100% | 53,824 psi | 83% | 2864 fps | 97.4% |
| Lovex S060 | <<locked>> | 82% | 57,711 psi | 89% | 2733 fps | 100% |
| Lovex S062 | <<locked>> | 84% | 56,608 psi | 87% | 2743 fps | 100% |
| Lovex S065 | <<locked>> | 90% | 56,376 psi | 87% | 2772 fps | 99.9% |
| Lovex S070 | <<locked>> | 92% | 57,769 psi | 89% | 2815 fps | 99.8% |
| Lovex S071ᴾ | <<locked>> | 100% | 46,688 psi | 72% | 2661 fps | 99.1% |
| Norma 201 | <<locked>> | 82% | 57,928 psi | 89% | 2753 fps | 100% |
| Norma 202 | <<locked>> | 82% | 58,784 psi | 90% | 2749 fps | 100% |
| Norma 203B | <<locked>> | 84% | 57,392 psi | 88% | 2799 fps | 100% |
| Norma 204 | <<locked>> | 92% | 56,318 psi | 87% | 2831 fps | 98.6% |
| Norma MRP | <<locked>> | 98% | 55,085 psi | 85% | 2913 fps | 99.6% |
| Norma URP | <<locked>> | 92% | 56,695 psi | 87% | 2831 fps | 100% |
| Ramshot Big Game | <<locked>> | 84% | 58,537 psi | 90% | 2828 fps | 100% |
| Ramshot Grandᴾ | <<locked>> | 100% | 54,433 psi | 84% | 2884 fps | 97.8% |
| Ramshot Hunter | <<locked>> | 92% | 55,347 psi | 85% | 2835 fps | 99.9% |
| Ramshot Magnumᴾ | <<locked>> | 100% | 48,428 psi | 75% | 2759 fps | 98.2% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 37,173 psi | 57% | 1755 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 84% | 55,448 psi | 85% | 2762 fps | 99.7% |
| ReloadSwiss RS 60 | <<locked>> | 86% | 55,898 psi | 86% | 2864 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 92% | 58,102 psi | 89% | 2874 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 92% | 56,202 psi | 86% | 2900 fps | 100% |
| ReloadSwiss RS 76ᴾ | <<locked>> | 100% | 44,614 psi | 69% | 2779 fps | 98.4% |
| Rottweil R 902 | <<locked>> | 84% | 58,755 psi | 90% | 2756 fps | 100% |
| Rottweil R 903 | <<locked>> | 86% | 55,492 psi | 85% | 2756 fps | 100% |
| Rottweil R 904 | <<locked>> | 96% | 56,855 psi | 87% | 2812 fps | 97.9% |
| Rottweil R 905 | <<locked>> | 98% | 57,566 psi | 89% | 2871 fps | 99% |
| Rottweil R 907 | <<locked>> | 90% | 58,175 psi | 89% | 2802 fps | 99.5% |
| Shooters World Long Rifle | <<locked>> | 90% | 56,376 psi | 87% | 2772 fps | 99.9% |
| Shooters World Precision | <<locked>> | 84% | 56,608 psi | 87% | 2743 fps | 100% |
| Shooters World SW4350 | <<locked>> | 92% | 57,769 psi | 89% | 2815 fps | 99.8% |
| SNPE Vectan SP 11 | <<locked>> | 86% | 56,782 psi | 87% | 2812 fps | 100% |
| SNPE Vectan SP 9 | <<locked>> | 82% | 57,667 psi | 89% | 2782 fps | 100% |
| SNPE Vectan Tubal 3000 | <<locked>> | 82% | 58,682 psi | 90% | 2680 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 86% | 56,217 psi | 86% | 2641 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 90% | 56,014 psi | 86% | 2726 fps | 99.5% |
| SNPE Vectan Tubal 8000 | <<locked>> | 98% | 57,072 psi | 88% | 2867 fps | 98.9% |
| Somchem S335 | <<locked>> | 82% | 58,305 psi | 90% | 2677 fps | 100% |
| Somchem S355 | <<locked>> | 86% | 55,303 psi | 85% | 2749 fps | 100% |
| Somchem S361 | <<locked>> | 96% | 58,653 psi | 90% | 2805 fps | 97.4% |
| Somchem S365 | <<locked>> | 94% | 56,144 psi | 86% | 2835 fps | 100% |
| Somchem S385 | <<locked>> | 98% | 58,175 psi | 89% | 2844 fps | 99.5% |
| Vihtavuori N135 | <<locked>> | 82% | 55,724 psi | 86% | 2664 fps | 100% |
| Vihtavuori N140 | <<locked>> | 82% | 55,912 psi | 86% | 2684 fps | 100% |
| Vihtavuori N150 | <<locked>> | 88% | 56,637 psi | 87% | 2726 fps | 100% |
| Vihtavuori N160 | <<locked>> | 92% | 58,798 psi | 90% | 2825 fps | 100% |
| Vihtavuori N165ᴾ | <<locked>> | 100% | 53,853 psi | 83% | 2769 fps | 98.8% |
| Vihtavuori N540 | <<locked>> | 84% | 57,348 psi | 88% | 2723 fps | 100% |
| Vihtavuori N550 | <<locked>> | 92% | 57,769 psi | 89% | 2831 fps | 100% |
| Vihtavuori N555 | <<locked>> | 98% | 55,201 psi | 85% | 2844 fps | 100% |
| Vihtavuori N560 | <<locked>> | 98% | 55,332 psi | 85% | 2904 fps | 97.3% |
| Winchester 6.5 StaBALL | <<locked>> | 92% | 58,595 psi | 90% | 2795 fps | 100% |
| Winchester 760 | <<locked>> | 90% | 56,724 psi | 87% | 2851 fps | 99.7% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 47,935 psi | 74% | 2884 fps | 100% |
| Winchester StaBALL Match | <<locked>> | 82% | 58,015 psi | 89% | 2792 fps | 100% |
| Winchester Supreme 780ᴾ | <<locked>> | 100% | 58,624 psi | 90% | 2844 fps | 98.9% |
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% | 53,200 psi | 82% | 2635 fps | 100% |
| Accurate 2700 | <<locked>> | 80% | 50,676 psi | 78% | 2648 fps | 98.4% |
| Accurate 3100 | <<locked>> | 84% | 32,532 psi | 50% | 2375 fps | 95.4% |
| Accurate 4064 | <<locked>> | 80% | 50,401 psi | 78% | 2641 fps | 100% |
| Accurate 4350 | <<locked>> | 80% | 38,725 psi | 60% | 2526 fps | 98.9% |
| Accurate MAGPRO | <<locked>> | 96% | 50,488 psi | 78% | 2825 fps | 95.6% |
| ADI AR 2208 | <<locked>> | 80% | 47,268 psi | 73% | 2618 fps | 100% |
| ADI AR 2209 | <<locked>> | 88% | 42,656 psi | 66% | 2618 fps | 95.8% |
| ADI AR 2213 | <<locked>> | 94% | 46,180 psi | 71% | 2713 fps | 95.3% |
| Alliant Power Pro 2000-MR | <<locked>> | 80% | 52,823 psi | 81% | 2835 fps | 100% |
| Alliant Power Pro Varmint | <<locked>> | 86% | 39,987 psi | 62% | 2559 fps | 95.1% |
| Alliant Power Pro Varmint | <<locked>> | 86% | 39,987 psi | 62% | 2559 fps | 95.1% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 48,080 psi | 74% | 2648 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 80% | 51,285 psi | 79% | 2713 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 80% | 37,521 psi | 58% | 2533 fps | 98.9% |
| Alliant Reloder-17 | 51.2 gr | 80% | 42,714 psi | 66% | 2654 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 86% | 39,566 psi | 61% | 2552 fps | 95% |
| Alliant Reloder-22 | <<locked>> | 90% | 39,929 psi | 61% | 2605 fps | 95.3% |
| Alliant Reloder-23 | <<locked>> | 80% | 27,572 psi | 42% | 2297 fps | 97% |
| Alliant Reloder-25 | <<locked>> | 88% | 31,299 psi | 48% | 2418 fps | 95.3% |
| Alliant Reloder-26 | 52.4 gr | 80% | 29,370 psi | 45% | 2402 fps | 95.3% |
| Bofors RP15 | <<locked>> | 94% | 41,959 psi | 65% | 2648 fps | 95.8% |
| Bofors RP3 | <<locked>> | 80% | 48,414 psi | 74% | 2657 fps | 100% |
| Bofors RP5 | <<locked>> | 90% | 39,929 psi | 61% | 2605 fps | 95.3% |
| Bofors RP7 | <<locked>> | 80% | 42,598 psi | 66% | 2536 fps | 97% |
| Hodgdon H380 | <<locked>> | 80% | 48,646 psi | 75% | 2667 fps | 99.8% |
| Hodgdon H414 | <<locked>> | 80% | 40,451 psi | 62% | 2569 fps | 97.1% |
| Hodgdon H4350 | <<locked>> | 80% | 43,424 psi | 67% | 2589 fps | 96.5% |
| Hodgdon H4831 | <<locked>> | 94% | 49,501 psi | 76% | 2720 fps | 95.6% |
| Hodgdon H4831 SC | <<locked>> | 94% | 48,457 psi | 75% | 2703 fps | 95.3% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 35,143 psi | 54% | 2428 fps | 99.3% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 53,055 psi | 82% | 2753 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 96% | 39,218 psi | 60% | 2657 fps | 95.3% |
| Hodgdon Superformance | <<locked>> | 80% | 39,465 psi | 61% | 2579 fps | 96.4% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,267 psi | 42% | 1532 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 53,838 psi | 83% | 2720 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 49,734 psi | 77% | 2651 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 80% | 52,170 psi | 80% | 2687 fps | 99.2% |
| IMR 4350 | <<locked>> | 80% | 38,130 psi | 59% | 2467 fps | 95.7% |
| IMR 4451 Enduron | <<locked>> | 80% | 43,947 psi | 68% | 2566 fps | 97.7% |
| IMR 4831 | <<locked>> | 80% | 37,202 psi | 57% | 2480 fps | 98.6% |
| IMR 4895 | <<locked>> | 80% | 52,634 psi | 81% | 2740 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 92% | 48,283 psi | 74% | 2664 fps | 95.5% |
| IMR 7828 SSC | <<locked>> | 96% | 47,253 psi | 73% | 2749 fps | 95.8% |
| Lovex S060 | <<locked>> | 80% | 54,317 psi | 84% | 2684 fps | 100% |
| Lovex S062 | <<locked>> | 80% | 49,995 psi | 77% | 2648 fps | 100% |
| Lovex S065 | <<locked>> | 80% | 41,437 psi | 64% | 2516 fps | 98.4% |
| Lovex S070 | <<locked>> | 80% | 39,624 psi | 61% | 2497 fps | 97% |
| Lovex S071 | <<locked>> | 88% | 31,662 psi | 49% | 2352 fps | 95% |
| Norma 201 | <<locked>> | 80% | 54,476 psi | 84% | 2703 fps | 100% |
| Norma 202 | <<locked>> | 80% | 55,230 psi | 85% | 2700 fps | 100% |
| Norma 203B | <<locked>> | 80% | 50,647 psi | 78% | 2700 fps | 100% |
| Norma 204 | <<locked>> | 84% | 43,105 psi | 66% | 2605 fps | 95.9% |
| Norma MRP | <<locked>> | 86% | 36,448 psi | 56% | 2556 fps | 95.6% |
| Norma URP | <<locked>> | 80% | 38,290 psi | 59% | 2516 fps | 98.7% |
| Ramshot Big Game | <<locked>> | 80% | 51,126 psi | 79% | 2723 fps | 100% |
| Ramshot Grand | <<locked>> | 94% | 43,947 psi | 68% | 2694 fps | 95.2% |
| Ramshot Hunter | <<locked>> | 80% | 37,231 psi | 57% | 2507 fps | 97% |
| Ramshot Magnum | <<locked>> | 94% | 39,102 psi | 60% | 2575 fps | 95.7% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 27,978 psi | 43% | 1572 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 48,559 psi | 75% | 2651 fps | 99.1% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 45,368 psi | 70% | 2703 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 38,363 psi | 59% | 2543 fps | 98.6% |
| ReloadSwiss RS 70 | 52 gr | 80% | 37,246 psi | 57% | 2549 fps | 98.1% |
| ReloadSwiss RS 76 | <<locked>> | 94% | 36,274 psi | 56% | 2582 fps | 95.3% |
| Rottweil R 902 | <<locked>> | 80% | 51,866 psi | 80% | 2657 fps | 100% |
| Rottweil R 903 | <<locked>> | 80% | 45,542 psi | 70% | 2605 fps | 100% |
| Rottweil R 904 | <<locked>> | 88% | 44,179 psi | 68% | 2598 fps | 95% |
| Rottweil R 905 | <<locked>> | 88% | 41,263 psi | 63% | 2592 fps | 95.8% |
| Rottweil R 907 | <<locked>> | 80% | 42,598 psi | 66% | 2536 fps | 97% |
| Shooters World Long Rifle | <<locked>> | 80% | 41,437 psi | 64% | 2516 fps | 98.4% |
| Shooters World Precision | <<locked>> | 80% | 49,995 psi | 77% | 2648 fps | 100% |
| Shooters World SW4350 | <<locked>> | 80% | 39,624 psi | 61% | 2497 fps | 97% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 46,847 psi | 72% | 2661 fps | 100% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 54,288 psi | 84% | 2736 fps | 100% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 55,071 psi | 85% | 2635 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 46,688 psi | 72% | 2510 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 40,640 psi | 63% | 2464 fps | 97.1% |
| SNPE Vectan Tubal 8000 | <<locked>> | 88% | 40,886 psi | 63% | 2585 fps | 95.6% |
| Somchem S335 | <<locked>> | 80% | 54,882 psi | 84% | 2631 fps | 100% |
| Somchem S355 | <<locked>> | 80% | 45,861 psi | 71% | 2605 fps | 100% |
| Somchem S361 | <<locked>> | 90% | 48,327 psi | 74% | 2644 fps | 95.3% |
| Somchem S365 | <<locked>> | 80% | 34,838 psi | 54% | 2477 fps | 99.9% |
| Somchem S385 | <<locked>> | 84% | 36,927 psi | 57% | 2470 fps | 95.2% |
| Vihtavuori N135 | <<locked>> | 80% | 52,228 psi | 80% | 2618 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 52,272 psi | 80% | 2631 fps | 100% |
| Vihtavuori N150 | <<locked>> | 80% | 43,700 psi | 67% | 2533 fps | 100% |
| Vihtavuori N160 | <<locked>> | 80% | 39,827 psi | 61% | 2516 fps | 98.9% |
| Vihtavuori N165 | <<locked>> | 90% | 38,783 psi | 60% | 2503 fps | 95.4% |
| Vihtavuori N540 | <<locked>> | 80% | 50,531 psi | 78% | 2631 fps | 100% |
| Vihtavuori N550 | <<locked>> | 80% | 39,117 psi | 60% | 2516 fps | 98.7% |
| Vihtavuori N555 | <<locked>> | 80% | 30,516 psi | 47% | 2372 fps | 97.1% |
| Vihtavuori N560 | <<locked>> | 94% | 48,370 psi | 74% | 2782 fps | 95.7% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 38,812 psi | 60% | 2487 fps | 99.9% |
| Winchester 760 | <<locked>> | 80% | 40,640 psi | 63% | 2572 fps | 97.1% |
| Winchester StaBALL HD | <<locked>> | 80% | 24,424 psi | 38% | 2274 fps | 95.8% |
| Winchester StaBALL Match | <<locked>> | 80% | 54,273 psi | 83% | 2740 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 90% | 41,321 psi | 64% | 2562 fps | 95.5% |
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 98 powders for .280 Ackley Improved loaded with the .284 | 160gr | Woodleigh PP SN. Alliant Reloder-26 delivers the highest muzzle velocity at 2,959 fps; across all powders the maximum-charge window runs from 1,716 fps to 2,959 fps. Accurate 3100 gives the best case fill at 100 %, and 98 of the 98 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (448 MPa), the top charges use 56–90 %, leaving at least 10 % headroom. The 160.0 gr projectile in 0.284" calls for a 1:12.0 twist; slower twists will usually not stabilise this weight. Accurate 3100, Accurate MAGPRO, ADI AR 2213 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-26, ReloadSwiss RS 70, Alliant Reloder-17 rank at the top here: for .280 Ackley Improved with the .284 | 160gr | Woodleigh PP SN 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.