Load Specifications
Load data in caliber .280 Ackley Improved with .284 | 156gr | Norma ORYX bullet and 96 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Alliant Reloder-26, Alliant Reloder-17 and Norma MRP.
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% | 56,942 psi | 88% | 2723 fps | 100% |
| Accurate 2700 | <<locked>> | 84% | 58,088 psi | 89% | 2802 fps | 99.3% |
| Accurate 3100ᴾ | <<locked>> | 100% | 56,405 psi | 87% | 2851 fps | 99.9% |
| Accurate 4064 | <<locked>> | 84% | 57,305 psi | 88% | 2779 fps | 100% |
| Accurate 4350 | <<locked>> | 92% | 58,595 psi | 90% | 2894 fps | 100% |
| Accurate MAGPROᴾ | <<locked>> | 100% | 58,610 psi | 90% | 2995 fps | 97.2% |
| ADI AR 2208 | <<locked>> | 86% | 57,000 psi | 88% | 2812 fps | 100% |
| ADI AR 2209 | <<locked>> | 96% | 55,390 psi | 85% | 2884 fps | 98.5% |
| ADI AR 2213ᴾ | <<locked>> | 100% | 57,029 psi | 88% | 2940 fps | 97.8% |
| Alliant Power Pro 2000-MR | <<locked>> | 82% | 56,942 psi | 88% | 2936 fps | 100% |
| Alliant Power Pro Varmint | <<locked>> | 96% | 55,767 psi | 86% | 2884 fps | 98.6% |
| Alliant Reloder- TS 15.5 | <<locked>> | 86% | 58,305 psi | 90% | 2838 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 84% | 58,450 psi | 90% | 2858 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 92% | 55,477 psi | 85% | 2897 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 88% | 56,855 psi | 87% | 2917 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 98% | 58,479 psi | 90% | 2927 fps | 99% |
| Alliant Reloder-22ᴾ | <<locked>> | 100% | 56,130 psi | 86% | 2936 fps | 98.8% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 52,881 psi | 81% | 2861 fps | 100% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 45,861 psi | 71% | 2792 fps | 99.6% |
| Alliant Reloder-26 | <<locked>> | 98% | 57,014 psi | 88% | 3005 fps | 100% |
| Bofors RP15ᴾ | <<locked>> | 100% | 51,285 psi | 79% | 2858 fps | 97.9% |
| Bofors RP3 | <<locked>> | 84% | 55,361 psi | 85% | 2802 fps | 100% |
| Bofors RP5ᴾ | <<locked>> | 100% | 56,130 psi | 86% | 2936 fps | 98.8% |
| Bofors RP7 | <<locked>> | 90% | 58,305 psi | 90% | 2844 fps | 99.4% |
| Hodgdon H380 | <<locked>> | 84% | 55,767 psi | 86% | 2818 fps | 100% |
| Hodgdon H414 | <<locked>> | 90% | 56,811 psi | 87% | 2894 fps | 99.6% |
| Hodgdon H4350 | <<locked>> | 88% | 56,449 psi | 87% | 2851 fps | 98.9% |
| Hodgdon H4831 | <<locked>> | 98% | 57,072 psi | 88% | 2884 fps | 97.1% |
| Hodgdon H4831 SC | <<locked>> | 98% | 55,869 psi | 86% | 2864 fps | 96.9% |
| Hodgdon Hybrid 100V | <<locked>> | 94% | 55,724 psi | 86% | 2818 fps | 100% |
| Hodgdon LEVERevolution | <<locked>> | 82% | 57,101 psi | 88% | 2851 fps | 100% |
| Hodgdon Retumboᴾ | <<locked>> | 100% | 44,947 psi | 69% | 2828 fps | 97.3% |
| Hodgdon Superformance | <<locked>> | 90% | 57,058 psi | 88% | 2930 fps | 99.5% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 36,680 psi | 56% | 1749 fps | 100% |
| Hodgdon VARGET | <<locked>> | 82% | 57,682 psi | 89% | 2815 fps | 100% |
| IMR 4064 | <<locked>> | 84% | 56,550 psi | 87% | 2792 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 82% | 55,564 psi | 85% | 2779 fps | 99.4% |
| IMR 4350 | <<locked>> | 92% | 55,970 psi | 86% | 2825 fps | 99.2% |
| IMR 4451 Enduron | <<locked>> | 88% | 56,318 psi | 87% | 2815 fps | 99.5% |
| IMR 4831 | <<locked>> | 94% | 58,581 psi | 90% | 2881 fps | 100% |
| IMR 4895 | <<locked>> | 82% | 56,173 psi | 86% | 2831 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 98% | 58,450 psi | 90% | 2867 fps | 97.5% |
| IMR 7828 SSCᴾ | <<locked>> | 100% | 54,143 psi | 83% | 2910 fps | 97.3% |
| Lovex S060 | <<locked>> | 82% | 57,899 psi | 89% | 2776 fps | 100% |
| Lovex S062 | <<locked>> | 84% | 57,043 psi | 88% | 2789 fps | 100% |
| Lovex S065 | <<locked>> | 90% | 56,579 psi | 87% | 2815 fps | 99.9% |
| Lovex S070 | <<locked>> | 92% | 57,856 psi | 89% | 2854 fps | 99.7% |
| Lovex S071ᴾ | <<locked>> | 100% | 46,891 psi | 72% | 2700 fps | 99% |
| Norma 201 | <<locked>> | 82% | 58,146 psi | 89% | 2795 fps | 100% |
| Norma 203B | <<locked>> | 84% | 57,725 psi | 89% | 2844 fps | 100% |
| Norma 204 | <<locked>> | 92% | 56,536 psi | 87% | 2877 fps | 98.5% |
| Norma MRP | <<locked>> | 98% | 55,666 psi | 86% | 2959 fps | 99.6% |
| Norma URP | <<locked>> | 92% | 56,739 psi | 87% | 2874 fps | 100% |
| Ramshot Big Game | <<locked>> | 84% | 58,653 psi | 90% | 2871 fps | 100% |
| Ramshot Grandᴾ | <<locked>> | 100% | 54,621 psi | 84% | 2927 fps | 97.8% |
| Ramshot Hunter | <<locked>> | 92% | 55,535 psi | 85% | 2881 fps | 99.8% |
| Ramshot Magnumᴾ | <<locked>> | 100% | 48,820 psi | 75% | 2802 fps | 98.2% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 37,376 psi | 58% | 1791 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 84% | 55,695 psi | 86% | 2805 fps | 99.7% |
| ReloadSwiss RS 60 | <<locked>> | 86% | 56,333 psi | 87% | 2910 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 92% | 58,305 psi | 90% | 2917 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 92% | 56,637 psi | 87% | 2946 fps | 100% |
| ReloadSwiss RS 76ᴾ | <<locked>> | 100% | 44,918 psi | 69% | 2822 fps | 98.3% |
| Rottweil R 902 | <<locked>> | 82% | 55,448 psi | 85% | 2749 fps | 100% |
| Rottweil R 903 | <<locked>> | 86% | 55,521 psi | 85% | 2799 fps | 100% |
| Rottweil R 904 | <<locked>> | 96% | 57,116 psi | 88% | 2854 fps | 97.8% |
| Rottweil R 905 | <<locked>> | 98% | 58,001 psi | 89% | 2920 fps | 99% |
| Rottweil R 907 | <<locked>> | 90% | 58,305 psi | 90% | 2844 fps | 99.4% |
| Shooters World Long Rifle | <<locked>> | 90% | 56,579 psi | 87% | 2815 fps | 99.9% |
| Shooters World Precision | <<locked>> | 84% | 57,043 psi | 88% | 2789 fps | 100% |
| Shooters World SW4350 | <<locked>> | 92% | 57,856 psi | 89% | 2854 fps | 99.7% |
| SNPE Vectan SP 11 | <<locked>> | 86% | 57,232 psi | 88% | 2858 fps | 100% |
| SNPE Vectan SP 9 | <<locked>> | 82% | 57,986 psi | 89% | 2828 fps | 100% |
| SNPE Vectan Tubal 3000 | <<locked>> | 82% | 58,682 psi | 90% | 2723 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 86% | 56,391 psi | 87% | 2684 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 90% | 56,057 psi | 86% | 2766 fps | 99.5% |
| SNPE Vectan Tubal 8000 | <<locked>> | 98% | 57,508 psi | 88% | 2913 fps | 98.9% |
| Somchem S335 | <<locked>> | 82% | 58,479 psi | 90% | 2720 fps | 100% |
| Somchem S355 | <<locked>> | 86% | 55,622 psi | 86% | 2795 fps | 100% |
| Somchem S361 | <<locked>> | 94% | 55,448 psi | 85% | 2799 fps | 96.8% |
| Somchem S365 | <<locked>> | 94% | 56,478 psi | 87% | 2877 fps | 100% |
| Somchem S385 | <<locked>> | 98% | 58,566 psi | 90% | 2890 fps | 99.5% |
| Vihtavuori N135 | <<locked>> | 82% | 55,738 psi | 86% | 2707 fps | 100% |
| Vihtavuori N140 | <<locked>> | 82% | 56,101 psi | 86% | 2726 fps | 100% |
| Vihtavuori N150 | <<locked>> | 88% | 56,855 psi | 87% | 2769 fps | 100% |
| Vihtavuori N160 | <<locked>> | 90% | 55,332 psi | 85% | 2818 fps | 100% |
| Vihtavuori N165ᴾ | <<locked>> | 100% | 54,172 psi | 83% | 2812 fps | 98.8% |
| Vihtavuori N540 | <<locked>> | 84% | 57,624 psi | 89% | 2766 fps | 100% |
| Vihtavuori N550 | <<locked>> | 92% | 58,059 psi | 89% | 2877 fps | 100% |
| Vihtavuori N555 | <<locked>> | 98% | 55,463 psi | 85% | 2887 fps | 100% |
| Vihtavuori N560 | <<locked>> | 98% | 55,869 psi | 86% | 2949 fps | 97.3% |
| Winchester 6.5 StaBALL | <<locked>> | 92% | 58,668 psi | 90% | 2835 fps | 100% |
| Winchester 760 | <<locked>> | 90% | 57,058 psi | 88% | 2897 fps | 99.6% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 48,240 psi | 74% | 2927 fps | 100% |
| Winchester StaBALL Match | <<locked>> | 82% | 58,276 psi | 90% | 2838 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 98% | 54,810 psi | 84% | 2828 fps | 98.4% |
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% | 53,476 psi | 82% | 2677 fps | 100% |
| Accurate 2700 | <<locked>> | 80% | 51,010 psi | 78% | 2694 fps | 98.4% |
| Accurate 3100 | <<locked>> | 84% | 32,822 psi | 50% | 2411 fps | 95.3% |
| Accurate 4064 | <<locked>> | 80% | 50,662 psi | 78% | 2687 fps | 100% |
| Accurate 4350 | <<locked>> | 80% | 38,914 psi | 60% | 2566 fps | 98.8% |
| Accurate MAGPRO | <<locked>> | 96% | 51,039 psi | 79% | 2871 fps | 95.5% |
| ADI AR 2208 | <<locked>> | 80% | 47,529 psi | 73% | 2661 fps | 99.9% |
| ADI AR 2209 | <<locked>> | 88% | 42,830 psi | 66% | 2657 fps | 95.7% |
| ADI AR 2213 | <<locked>> | 94% | 46,615 psi | 72% | 2759 fps | 95.3% |
| Alliant Power Pro 2000-MR | <<locked>> | 80% | 52,852 psi | 81% | 2877 fps | 100% |
| Alliant Power Pro Varmint | <<locked>> | 88% | 42,989 psi | 66% | 2657 fps | 95.8% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 48,312 psi | 74% | 2687 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 80% | 51,474 psi | 79% | 2756 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 80% | 37,739 psi | 58% | 2572 fps | 98.9% |
| Alliant Reloder-17 | 52.4 gr | 80% | 42,801 psi | 66% | 2694 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 88% | 42,540 psi | 65% | 2651 fps | 95.8% |
| Alliant Reloder-22 | <<locked>> | 90% | 40,016 psi | 62% | 2641 fps | 95.1% |
| Alliant Reloder-23 | <<locked>> | 80% | 27,760 psi | 43% | 2333 fps | 96.9% |
| Alliant Reloder-25 | <<locked>> | 88% | 31,444 psi | 48% | 2451 fps | 95.1% |
| Alliant Reloder-26 | 53.7 gr | 80% | 29,559 psi | 45% | 2438 fps | 95.1% |
| Bofors RP15 | <<locked>> | 94% | 42,221 psi | 65% | 2687 fps | 95.7% |
| Bofors RP3 | <<locked>> | 80% | 48,631 psi | 75% | 2697 fps | 100% |
| Bofors RP5 | <<locked>> | 90% | 40,016 psi | 62% | 2641 fps | 95.1% |
| Bofors RP7 | <<locked>> | 80% | 42,772 psi | 66% | 2579 fps | 96.9% |
| Hodgdon H380 | <<locked>> | 80% | 49,023 psi | 75% | 2713 fps | 99.8% |
| Hodgdon H414 | <<locked>> | 80% | 40,770 psi | 63% | 2608 fps | 97% |
| Hodgdon H4350 | <<locked>> | 80% | 43,584 psi | 67% | 2628 fps | 96.4% |
| Hodgdon H4831 | <<locked>> | 94% | 49,676 psi | 76% | 2762 fps | 95.5% |
| Hodgdon H4831 SC | <<locked>> | 94% | 48,950 psi | 75% | 2749 fps | 95.3% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 35,172 psi | 54% | 2464 fps | 99.3% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 53,417 psi | 82% | 2799 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 96% | 39,537 psi | 61% | 2700 fps | 95.3% |
| Hodgdon Superformance | <<locked>> | 80% | 39,639 psi | 61% | 2618 fps | 96.3% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,267 psi | 42% | 1558 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 54,041 psi | 83% | 2762 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 50,024 psi | 77% | 2694 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 80% | 52,301 psi | 80% | 2726 fps | 99.1% |
| IMR 4350 | <<locked>> | 80% | 38,305 psi | 59% | 2503 fps | 95.6% |
| IMR 4451 Enduron | <<locked>> | 80% | 44,092 psi | 68% | 2605 fps | 97.6% |
| IMR 4831 | <<locked>> | 80% | 37,376 psi | 58% | 2516 fps | 98.5% |
| IMR 4895 | <<locked>> | 80% | 52,823 psi | 81% | 2782 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 92% | 48,544 psi | 75% | 2707 fps | 95.4% |
| IMR 7828 SSC | <<locked>> | 96% | 47,384 psi | 73% | 2785 fps | 95.7% |
| Lovex S060 | <<locked>> | 80% | 54,549 psi | 84% | 2726 fps | 100% |
| Lovex S062 | <<locked>> | 80% | 50,285 psi | 77% | 2690 fps | 100% |
| Lovex S065 | <<locked>> | 80% | 41,640 psi | 64% | 2556 fps | 98.3% |
| Lovex S070 | <<locked>> | 80% | 39,784 psi | 61% | 2539 fps | 96.9% |
| Lovex S071 | <<locked>> | 90% | 34,084 psi | 52% | 2444 fps | 95.9% |
| Norma 201 | <<locked>> | 80% | 54,723 psi | 84% | 2749 fps | 100% |
| Norma 203B | <<locked>> | 80% | 50,850 psi | 78% | 2743 fps | 100% |
| Norma 204 | <<locked>> | 84% | 43,308 psi | 67% | 2648 fps | 95.8% |
| Norma MRP | 56.1 gr | 86% | 36,753 psi | 57% | 2598 fps | 95.5% |
| Norma URP | <<locked>> | 80% | 38,464 psi | 59% | 2556 fps | 98.6% |
| Ramshot Big Game | <<locked>> | 80% | 51,155 psi | 79% | 2762 fps | 100% |
| Ramshot Grand | <<locked>> | 94% | 44,295 psi | 68% | 2740 fps | 95.1% |
| Ramshot Hunter | <<locked>> | 80% | 37,347 psi | 57% | 2543 fps | 96.8% |
| Ramshot Magnum | <<locked>> | 94% | 39,392 psi | 61% | 2615 fps | 95.6% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 27,934 psi | 43% | 1601 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 48,921 psi | 75% | 2697 fps | 99% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 45,455 psi | 70% | 2743 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 38,682 psi | 60% | 2582 fps | 98.5% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 37,260 psi | 57% | 2585 fps | 97.9% |
| ReloadSwiss RS 76 | <<locked>> | 94% | 36,477 psi | 56% | 2621 fps | 95.1% |
| Rottweil R 902 | <<locked>> | 80% | 52,185 psi | 80% | 2703 fps | 100% |
| Rottweil R 903 | <<locked>> | 80% | 45,759 psi | 70% | 2644 fps | 100% |
| Rottweil R 904 | <<locked>> | 90% | 47,210 psi | 73% | 2690 fps | 95.7% |
| Rottweil R 905 | <<locked>> | 88% | 41,698 psi | 64% | 2635 fps | 95.7% |
| Rottweil R 907 | <<locked>> | 80% | 42,772 psi | 66% | 2579 fps | 96.9% |
| Shooters World Long Rifle | <<locked>> | 80% | 41,640 psi | 64% | 2556 fps | 98.3% |
| Shooters World Precision | <<locked>> | 80% | 50,285 psi | 77% | 2690 fps | 100% |
| Shooters World SW4350 | <<locked>> | 80% | 39,784 psi | 61% | 2539 fps | 96.9% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 46,934 psi | 72% | 2700 fps | 100% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 54,389 psi | 84% | 2779 fps | 100% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 55,434 psi | 85% | 2677 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 47,007 psi | 72% | 2552 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 40,770 psi | 63% | 2503 fps | 97% |
| SNPE Vectan Tubal 8000 | <<locked>> | 88% | 41,307 psi | 64% | 2631 fps | 95.6% |
| Somchem S335 | <<locked>> | 80% | 55,158 psi | 85% | 2677 fps | 100% |
| Somchem S355 | <<locked>> | 80% | 46,079 psi | 71% | 2644 fps | 100% |
| Somchem S361 | <<locked>> | 90% | 48,486 psi | 75% | 2684 fps | 95.2% |
| Somchem S365 | <<locked>> | 80% | 35,041 psi | 54% | 2516 fps | 99.9% |
| Somchem S385 | <<locked>> | 84% | 36,985 psi | 57% | 2503 fps | 95% |
| Vihtavuori N135 | <<locked>> | 80% | 52,591 psi | 81% | 2664 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 52,504 psi | 81% | 2677 fps | 100% |
| Vihtavuori N150 | <<locked>> | 80% | 43,918 psi | 68% | 2575 fps | 100% |
| Vihtavuori N160 | <<locked>> | 80% | 40,001 psi | 62% | 2556 fps | 98.9% |
| Vihtavuori N165 | <<locked>> | 90% | 38,899 psi | 60% | 2539 fps | 95.3% |
| Vihtavuori N540 | <<locked>> | 80% | 50,923 psi | 78% | 2674 fps | 100% |
| Vihtavuori N550 | <<locked>> | 80% | 39,465 psi | 61% | 2559 fps | 98.6% |
| Vihtavuori N555 | <<locked>> | 80% | 30,705 psi | 47% | 2408 fps | 97% |
| Vihtavuori N560 | <<locked>> | 94% | 48,776 psi | 75% | 2828 fps | 95.6% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 39,030 psi | 60% | 2526 fps | 99.9% |
| Winchester 760 | <<locked>> | 80% | 40,770 psi | 63% | 2608 fps | 97% |
| Winchester StaBALL HD | <<locked>> | 80% | 24,497 psi | 38% | 2303 fps | 95.5% |
| Winchester StaBALL Match | <<locked>> | 80% | 54,578 psi | 84% | 2785 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 90% | 41,568 psi | 64% | 2598 fps | 95.4% |
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 96 powders for .280 Ackley Improved loaded with the .284 | 156gr | Norma ORYX. Alliant Reloder-26 delivers the highest muzzle velocity at 3,005 fps; across all powders the maximum-charge window runs from 1,749 fps to 3,005 fps. Accurate 3100 gives the best case fill at 100 %, and 96 of the 96 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 156.0 gr projectile in 0.284" calls for a 1:13.5 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, Alliant Reloder-17, Norma MRP rank at the top here: for .280 Ackley Improved with the .284 | 156gr | Norma ORYX 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.