Load Specifications
Load data in caliber .280 Ackley Improved with .284 | 160gr | Prvi Partizan PSP BT 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, ReloadSwiss RS 70 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: 24"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 2495 | <<locked>> | 82% | 56,420 psi | 87% | 2674 fps | 100% |
| Accurate 2700 | <<locked>> | 84% | 57,450 psi | 88% | 2749 fps | 99.2% |
| Accurate 3100ᴾ | <<locked>> | 100% | 55,579 psi | 86% | 2799 fps | 99.9% |
| Accurate 4064 | <<locked>> | 84% | 56,898 psi | 88% | 2730 fps | 100% |
| Accurate 4350 | <<locked>> | 92% | 57,653 psi | 89% | 2841 fps | 100% |
| Accurate MAGPROᴾ | <<locked>> | 100% | 57,769 psi | 89% | 2940 fps | 97.1% |
| ADI AR 2208 | <<locked>> | 86% | 56,724 psi | 87% | 2762 fps | 100% |
| ADI AR 2209 | <<locked>> | 98% | 58,407 psi | 90% | 2887 fps | 98.9% |
| ADI AR 2213ᴾ | <<locked>> | 100% | 56,043 psi | 86% | 2884 fps | 97.6% |
| Alliant Power Pro 2000-MR | <<locked>> | 82% | 56,115 psi | 86% | 2884 fps | 100% |
| Alliant Reloder- TS 15.5 | <<locked>> | 86% | 57,435 psi | 88% | 2782 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 84% | 57,856 psi | 89% | 2808 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 94% | 58,450 psi | 90% | 2897 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 88% | 55,985 psi | 86% | 2864 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 98% | 57,899 psi | 89% | 2877 fps | 98.9% |
| Alliant Reloder-22ᴾ | <<locked>> | 100% | 55,071 psi | 85% | 2881 fps | 98.7% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 52,228 psi | 80% | 2812 fps | 100% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 45,208 psi | 70% | 2743 fps | 99.5% |
| Alliant Reloder-26 | <<locked>> | 98% | 55,999 psi | 86% | 2949 fps | 100% |
| Bofors RP15ᴾ | <<locked>> | 100% | 50,488 psi | 78% | 2805 fps | 97.9% |
| Bofors RP3 | <<locked>> | 86% | 58,726 psi | 90% | 2802 fps | 100% |
| Bofors RP5ᴾ | <<locked>> | 100% | 55,071 psi | 85% | 2881 fps | 98.7% |
| Bofors RP7 | <<locked>> | 90% | 57,696 psi | 89% | 2792 fps | 99.4% |
| Hodgdon H380 | <<locked>> | 84% | 55,245 psi | 85% | 2769 fps | 100% |
| Hodgdon H414 | <<locked>> | 90% | 55,956 psi | 86% | 2838 fps | 99.6% |
| Hodgdon H4350 | <<locked>> | 88% | 55,811 psi | 86% | 2799 fps | 98.8% |
| Hodgdon H4831 | <<locked>> | 98% | 56,304 psi | 87% | 2831 fps | 97% |
| Hodgdon H4831 SC | <<locked>> | 98% | 55,071 psi | 85% | 2812 fps | 96.8% |
| Hodgdon Hybrid 100V | <<locked>> | 96% | 58,813 psi | 90% | 2818 fps | 100% |
| Hodgdon LEVERevolution | <<locked>> | 82% | 56,565 psi | 87% | 2802 fps | 100% |
| Hodgdon Retumboᴾ | <<locked>> | 100% | 44,353 psi | 68% | 2776 fps | 97.3% |
| Hodgdon Superformance | <<locked>> | 90% | 56,231 psi | 87% | 2877 fps | 99.5% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 36,521 psi | 56% | 1713 fps | 100% |
| Hodgdon VARGET | <<locked>> | 82% | 57,029 psi | 88% | 2762 fps | 100% |
| IMR 4064 | <<locked>> | 84% | 56,159 psi | 86% | 2746 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 84% | 58,755 psi | 90% | 2782 fps | 99.7% |
| IMR 4350 | <<locked>> | 94% | 58,682 psi | 90% | 2825 fps | 99.5% |
| IMR 4451 Enduron | <<locked>> | 88% | 55,956 psi | 86% | 2769 fps | 99.5% |
| IMR 4831 | <<locked>> | 94% | 58,088 psi | 89% | 2831 fps | 100% |
| IMR 4895 | <<locked>> | 82% | 55,767 psi | 86% | 2782 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 98% | 57,653 psi | 89% | 2815 fps | 97.4% |
| IMR 7828 SSCᴾ | <<locked>> | 100% | 53,403 psi | 82% | 2854 fps | 97.3% |
| Lovex S060 | <<locked>> | 82% | 57,464 psi | 88% | 2726 fps | 100% |
| Lovex S062 | <<locked>> | 84% | 56,391 psi | 87% | 2736 fps | 100% |
| Lovex S065 | <<locked>> | 90% | 55,927 psi | 86% | 2762 fps | 99.9% |
| Lovex S070 | <<locked>> | 92% | 57,276 psi | 88% | 2805 fps | 99.7% |
| Lovex S071ᴾ | <<locked>> | 100% | 46,209 psi | 71% | 2651 fps | 99% |
| Norma 201 | <<locked>> | 82% | 57,696 psi | 89% | 2746 fps | 100% |
| Norma 202 | <<locked>> | 82% | 58,552 psi | 90% | 2743 fps | 100% |
| Norma 203B | <<locked>> | 84% | 57,130 psi | 88% | 2792 fps | 100% |
| Norma 204 | <<locked>> | 92% | 55,869 psi | 86% | 2825 fps | 98.5% |
| Norma MRPᴾ | <<locked>> | 100% | 58,697 psi | 90% | 2966 fps | 99.8% |
| Norma URP | <<locked>> | 92% | 56,173 psi | 86% | 2825 fps | 100% |
| Ramshot Big Game | <<locked>> | 84% | 58,001 psi | 89% | 2822 fps | 100% |
| Ramshot Grandᴾ | <<locked>> | 100% | 54,041 psi | 83% | 2877 fps | 97.7% |
| Ramshot Hunter | <<locked>> | 94% | 58,711 psi | 90% | 2884 fps | 100% |
| Ramshot Magnumᴾ | <<locked>> | 100% | 48,066 psi | 74% | 2749 fps | 98.1% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 37,231 psi | 57% | 1755 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 86% | 58,769 psi | 90% | 2808 fps | 99.9% |
| ReloadSwiss RS 60 | <<locked>> | 86% | 55,317 psi | 85% | 2854 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 92% | 57,580 psi | 89% | 2867 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 92% | 56,043 psi | 86% | 2897 fps | 100% |
| ReloadSwiss RS 76ᴾ | <<locked>> | 100% | 44,295 psi | 68% | 2772 fps | 98.3% |
| Rottweil R 902 | <<locked>> | 84% | 58,465 psi | 90% | 2749 fps | 100% |
| Rottweil R 903 | <<locked>> | 88% | 58,624 psi | 90% | 2799 fps | 100% |
| Rottweil R 904 | <<locked>> | 96% | 56,449 psi | 87% | 2802 fps | 97.8% |
| Rottweil R 905 | <<locked>> | 98% | 57,072 psi | 88% | 2864 fps | 98.9% |
| Rottweil R 907 | <<locked>> | 90% | 57,696 psi | 89% | 2792 fps | 99.4% |
| Shooters World Long Rifle | <<locked>> | 90% | 55,927 psi | 86% | 2762 fps | 99.9% |
| Shooters World Precision | <<locked>> | 84% | 56,391 psi | 87% | 2736 fps | 100% |
| Shooters World SW4350 | <<locked>> | 92% | 57,276 psi | 88% | 2805 fps | 99.7% |
| SNPE Vectan SP 11 | <<locked>> | 86% | 56,579 psi | 87% | 2808 fps | 100% |
| SNPE Vectan SP 9 | <<locked>> | 82% | 57,464 psi | 88% | 2779 fps | 100% |
| SNPE Vectan Tubal 3000 | <<locked>> | 82% | 58,436 psi | 90% | 2674 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 86% | 55,985 psi | 86% | 2635 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 90% | 55,506 psi | 85% | 2717 fps | 99.5% |
| SNPE Vectan Tubal 8000 | <<locked>> | 98% | 56,579 psi | 87% | 2858 fps | 98.9% |
| Somchem S335 | <<locked>> | 82% | 58,059 psi | 89% | 2674 fps | 100% |
| Somchem S355 | <<locked>> | 88% | 58,291 psi | 90% | 2789 fps | 100% |
| Somchem S361 | <<locked>> | 96% | 58,218 psi | 90% | 2795 fps | 97.3% |
| Somchem S365 | <<locked>> | 94% | 55,564 psi | 85% | 2825 fps | 100% |
| Somchem S385 | <<locked>> | 98% | 57,725 psi | 89% | 2838 fps | 99.4% |
| Vihtavuori N135 | <<locked>> | 84% | 58,798 psi | 90% | 2703 fps | 100% |
| Vihtavuori N140 | <<locked>> | 82% | 55,361 psi | 85% | 2674 fps | 100% |
| Vihtavuori N150 | <<locked>> | 88% | 56,130 psi | 86% | 2717 fps | 100% |
| Vihtavuori N160 | <<locked>> | 92% | 58,320 psi | 90% | 2818 fps | 100% |
| Vihtavuori N165ᴾ | <<locked>> | 100% | 53,447 psi | 82% | 2759 fps | 98.7% |
| Vihtavuori N540 | <<locked>> | 84% | 57,159 psi | 88% | 2720 fps | 100% |
| Vihtavuori N550 | <<locked>> | 92% | 57,305 psi | 88% | 2825 fps | 100% |
| Vihtavuori N555ᴾ | <<locked>> | 100% | 58,363 psi | 90% | 2887 fps | 100% |
| Vihtavuori N560 | <<locked>> | 98% | 54,911 psi | 84% | 2894 fps | 97.2% |
| Winchester 6.5 StaBALL | <<locked>> | 92% | 58,160 psi | 89% | 2785 fps | 100% |
| Winchester 760 | <<locked>> | 90% | 56,260 psi | 87% | 2844 fps | 99.6% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 47,123 psi | 72% | 2871 fps | 100% |
| Winchester StaBALL Match | <<locked>> | 82% | 57,827 psi | 89% | 2785 fps | 100% |
| Winchester Supreme 780ᴾ | <<locked>> | 100% | 58,204 psi | 90% | 2838 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% | 52,866 psi | 81% | 2628 fps | 100% |
| Accurate 2700 | <<locked>> | 80% | 50,488 psi | 78% | 2644 fps | 98.4% |
| Accurate 3100 | <<locked>> | 84% | 32,358 psi | 50% | 2369 fps | 95.3% |
| Accurate 4064 | <<locked>> | 80% | 50,125 psi | 77% | 2638 fps | 100% |
| Accurate 4350 | <<locked>> | 80% | 38,450 psi | 59% | 2520 fps | 98.8% |
| Accurate MAGPRO | <<locked>> | 96% | 50,053 psi | 77% | 2815 fps | 95.4% |
| ADI AR 2208 | <<locked>> | 80% | 47,036 psi | 72% | 2612 fps | 99.9% |
| ADI AR 2209 | <<locked>> | 88% | 42,264 psi | 65% | 2608 fps | 95.7% |
| ADI AR 2213 | <<locked>> | 94% | 46,064 psi | 71% | 2710 fps | 95.2% |
| Alliant Power Pro 2000-MR | <<locked>> | 80% | 52,243 psi | 80% | 2825 fps | 100% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 47,819 psi | 74% | 2641 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 80% | 51,053 psi | 79% | 2707 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 80% | 37,304 psi | 57% | 2526 fps | 98.9% |
| Alliant Reloder-17 | <<locked>> | 80% | 42,235 psi | 65% | 2644 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 88% | 41,930 psi | 65% | 2602 fps | 95.7% |
| Alliant Reloder-22 | <<locked>> | 90% | 39,523 psi | 61% | 2595 fps | 95.1% |
| Alliant Reloder-23 | <<locked>> | 80% | 27,398 psi | 42% | 2290 fps | 96.9% |
| Alliant Reloder-25 | <<locked>> | 88% | 30,995 psi | 48% | 2405 fps | 95% |
| Alliant Reloder-26 | 52.1 gr | 80% | 29,225 psi | 45% | 2395 fps | 95.1% |
| Bofors RP15 | <<locked>> | 94% | 41,582 psi | 64% | 2638 fps | 95.6% |
| Bofors RP3 | <<locked>> | 80% | 48,196 psi | 74% | 2651 fps | 100% |
| Bofors RP5 | <<locked>> | 90% | 39,523 psi | 61% | 2595 fps | 95.1% |
| Bofors RP7 | <<locked>> | 80% | 42,366 psi | 65% | 2530 fps | 96.9% |
| Hodgdon H380 | <<locked>> | 80% | 48,414 psi | 74% | 2661 fps | 99.8% |
| Hodgdon H414 | <<locked>> | 80% | 40,234 psi | 62% | 2562 fps | 97% |
| Hodgdon H4350 | <<locked>> | 80% | 43,207 psi | 66% | 2582 fps | 96.4% |
| Hodgdon H4831 | <<locked>> | 94% | 49,110 psi | 76% | 2713 fps | 95.5% |
| Hodgdon H4831 SC | <<locked>> | 94% | 48,298 psi | 74% | 2700 fps | 95.2% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 34,911 psi | 54% | 2425 fps | 99.3% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 52,837 psi | 81% | 2749 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 96% | 39,059 psi | 60% | 2651 fps | 95.2% |
| Hodgdon Superformance | 53.7 gr | 80% | 39,102 psi | 60% | 2572 fps | 96.2% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,253 psi | 42% | 1529 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 53,548 psi | 82% | 2713 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 49,487 psi | 76% | 2644 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 80% | 51,692 psi | 80% | 2674 fps | 99.1% |
| IMR 4350 | <<locked>> | 80% | 37,927 psi | 58% | 2461 fps | 95.6% |
| IMR 4451 Enduron | <<locked>> | 80% | 43,700 psi | 67% | 2559 fps | 97.6% |
| IMR 4831 | <<locked>> | 80% | 36,767 psi | 57% | 2470 fps | 98.5% |
| IMR 4895 | <<locked>> | 80% | 52,388 psi | 81% | 2733 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 92% | 47,877 psi | 74% | 2654 fps | 95.4% |
| IMR 7828 SSC | <<locked>> | 96% | 46,847 psi | 72% | 2740 fps | 95.6% |
| Lovex S060 | <<locked>> | 80% | 54,070 psi | 83% | 2677 fps | 100% |
| Lovex S062 | <<locked>> | 80% | 49,748 psi | 77% | 2641 fps | 100% |
| Lovex S065 | <<locked>> | 80% | 41,234 psi | 63% | 2510 fps | 98.3% |
| Lovex S070 | <<locked>> | 80% | 39,378 psi | 61% | 2493 fps | 96.9% |
| Lovex S071 | <<locked>> | 90% | 33,620 psi | 52% | 2398 fps | 95.8% |
| Norma 201 | <<locked>> | 80% | 54,172 psi | 83% | 2697 fps | 100% |
| Norma 202 | <<locked>> | 80% | 54,984 psi | 85% | 2694 fps | 100% |
| Norma 203B | <<locked>> | 80% | 50,415 psi | 78% | 2694 fps | 100% |
| Norma 204 | <<locked>> | 84% | 42,641 psi | 66% | 2595 fps | 95.7% |
| Norma MRP | <<locked>> | 86% | 36,274 psi | 56% | 2549 fps | 95.4% |
| Norma URP | <<locked>> | 80% | 38,029 psi | 59% | 2510 fps | 98.6% |
| Ramshot Big Game | <<locked>> | 80% | 50,633 psi | 78% | 2713 fps | 100% |
| Ramshot Grand | <<locked>> | 96% | 46,847 psi | 72% | 2749 fps | 96% |
| Ramshot Hunter | <<locked>> | 80% | 36,854 psi | 57% | 2497 fps | 96.8% |
| Ramshot Magnum | <<locked>> | 94% | 38,769 psi | 60% | 2566 fps | 95.5% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 27,746 psi | 43% | 1565 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 48,370 psi | 74% | 2648 fps | 99% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 44,875 psi | 69% | 2694 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 38,159 psi | 59% | 2536 fps | 98.5% |
| ReloadSwiss RS 70 | 51.6 gr | 80% | 36,854 psi | 57% | 2539 fps | 97.9% |
| ReloadSwiss RS 76 | <<locked>> | 94% | 35,984 psi | 55% | 2572 fps | 95% |
| Rottweil R 902 | <<locked>> | 80% | 51,605 psi | 79% | 2651 fps | 100% |
| Rottweil R 903 | <<locked>> | 80% | 45,281 psi | 70% | 2598 fps | 100% |
| Rottweil R 904 | <<locked>> | 90% | 46,630 psi | 72% | 2641 fps | 95.7% |
| Rottweil R 905 | <<locked>> | 88% | 41,046 psi | 63% | 2585 fps | 95.6% |
| Rottweil R 907 | <<locked>> | 80% | 42,366 psi | 65% | 2530 fps | 96.9% |
| Shooters World Long Rifle | <<locked>> | 80% | 41,234 psi | 63% | 2510 fps | 98.3% |
| Shooters World Precision | <<locked>> | 80% | 49,748 psi | 77% | 2641 fps | 100% |
| Shooters World SW4350 | <<locked>> | 80% | 39,378 psi | 61% | 2493 fps | 96.9% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 46,369 psi | 71% | 2651 fps | 100% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 53,780 psi | 83% | 2726 fps | 100% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 54,795 psi | 84% | 2628 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 46,441 psi | 71% | 2503 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 40,408 psi | 62% | 2457 fps | 97% |
| SNPE Vectan Tubal 8000 | <<locked>> | 88% | 40,669 psi | 63% | 2579 fps | 95.5% |
| Somchem S335 | <<locked>> | 80% | 54,650 psi | 84% | 2628 fps | 100% |
| Somchem S355 | <<locked>> | 80% | 45,571 psi | 70% | 2598 fps | 100% |
| Somchem S361 | <<locked>> | 90% | 47,935 psi | 74% | 2635 fps | 95.1% |
| Somchem S365 | <<locked>> | 80% | 34,592 psi | 53% | 2470 fps | 99.9% |
| Somchem S385 | <<locked>> | 84% | 36,521 psi | 56% | 2461 fps | 95% |
| Vihtavuori N135 | <<locked>> | 80% | 51,924 psi | 80% | 2615 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 52,025 psi | 80% | 2628 fps | 100% |
| Vihtavuori N150 | <<locked>> | 80% | 43,453 psi | 67% | 2530 fps | 100% |
| Vihtavuori N160 | <<locked>> | 80% | 39,595 psi | 61% | 2513 fps | 98.9% |
| Vihtavuori N165 | <<locked>> | 90% | 38,363 psi | 59% | 2493 fps | 95.2% |
| Vihtavuori N540 | <<locked>> | 80% | 50,314 psi | 77% | 2625 fps | 100% |
| Vihtavuori N550 | <<locked>> | 80% | 38,928 psi | 60% | 2510 fps | 98.6% |
| Vihtavuori N555 | <<locked>> | 80% | 30,255 psi | 47% | 2365 fps | 97% |
| Vihtavuori N560 | <<locked>> | 94% | 47,979 psi | 74% | 2772 fps | 95.5% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 38,450 psi | 59% | 2477 fps | 99.9% |
| Winchester 760 | <<locked>> | 80% | 40,422 psi | 62% | 2566 fps | 97% |
| Winchester StaBALL HD | <<locked>> | 80% | 24,163 psi | 37% | 2260 fps | 95.5% |
| Winchester StaBALL Match | <<locked>> | 80% | 54,027 psi | 83% | 2736 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 90% | 41,133 psi | 63% | 2556 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 104 powders for .280 Ackley Improved loaded with the .284 | 160gr | Prvi Partizan PSP BT. Norma MRP delivers the highest muzzle velocity at 2,966 fps; across all powders the maximum-charge window runs from 1,713 fps to 2,966 fps. Accurate 3100 gives the best case fill at 100 %, and 104 of the 104 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (448 MPa), the top charges use 49–90 %, leaving at least 10 % headroom. The 160.0 gr projectile in 0.284" calls for a 1:11.5 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, ReloadSwiss RS 70, Hodgdon Superformance rank at the top here: for .280 Ackley Improved with the .284 | 160gr | Prvi Partizan PSP BT they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, ADI AR 2217, Baschieri & Pellagri 109, Bofors RP30 burn incompletely and react more sensitively to barrel length and temperature. Always begin at the start load and work up in small increments while checking case and primer for pressure signs.