Load Specifications
Load data in caliber .280 Ackley Improved with .284 | 170gr | Sierra RN Prohunter bullet and 90 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Norma MRP, Vihtavuori N560 and Accurate MAGPRO.
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 2700 | <<locked>> | 82% | 56,565 psi | 87% | 2667 fps | 99.5% |
| Accurate 3100 | <<locked>> | 98% | 55,593 psi | 86% | 2723 fps | 100% |
| Accurate 4064 | <<locked>> | 82% | 56,362 psi | 87% | 2641 fps | 100% |
| Accurate 4350 | <<locked>> | 90% | 57,566 psi | 89% | 2759 fps | 100% |
| Accurate MAGPRO | <<locked>> | 98% | 57,638 psi | 89% | 2864 fps | 97.8% |
| ADI AR 2208 | <<locked>> | 84% | 55,869 psi | 86% | 2674 fps | 100% |
| ADI AR 2209 | <<locked>> | 96% | 58,131 psi | 89% | 2808 fps | 99.4% |
| ADI AR 2213 | <<locked>> | 98% | 55,724 psi | 86% | 2812 fps | 98.3% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 38,421 psi | 59% | 2546 fps | 97.4% |
| Alliant Reloder- TS 15.5 | <<locked>> | 84% | 57,058 psi | 88% | 2697 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 82% | 57,116 psi | 88% | 2720 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 92% | 58,073 psi | 89% | 2808 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 86% | 55,753 psi | 86% | 2779 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 96% | 57,406 psi | 88% | 2795 fps | 99.3% |
| Alliant Reloder-22 | <<locked>> | 98% | 55,129 psi | 85% | 2805 fps | 99.2% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 55,796 psi | 86% | 2779 fps | 100% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 48,283 psi | 74% | 2726 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 96% | 56,217 psi | 86% | 2867 fps | 100% |
| Baschieri & Pellagri 109ᴾ | <<locked>> | 100% | 58,117 psi | 89% | 2772 fps | 95.8% |
| Bofors RP15ᴾ | <<locked>> | 100% | 53,998 psi | 83% | 2789 fps | 99% |
| Bofors RP3 | <<locked>> | 84% | 58,117 psi | 89% | 2717 fps | 100% |
| Bofors RP30ᴾ | <<locked>> | 100% | 44,338 psi | 68% | 2657 fps | 96.7% |
| Bofors RP5 | <<locked>> | 98% | 55,129 psi | 85% | 2805 fps | 99.2% |
| Bofors RP7 | <<locked>> | 88% | 57,145 psi | 88% | 2710 fps | 99.7% |
| Hodgdon H1000ᴾ | <<locked>> | 100% | 47,892 psi | 74% | 2674 fps | 97.6% |
| Hodgdon H380 | <<locked>> | 84% | 58,131 psi | 89% | 2733 fps | 100% |
| Hodgdon H414 | <<locked>> | 88% | 55,521 psi | 85% | 2756 fps | 99.8% |
| Hodgdon H4350 | <<locked>> | 88% | 58,668 psi | 90% | 2769 fps | 99.5% |
| Hodgdon H4831 | <<locked>> | 96% | 55,709 psi | 86% | 2749 fps | 97.7% |
| Hodgdon H4831 SC | <<locked>> | 98% | 58,508 psi | 90% | 2792 fps | 98.1% |
| Hodgdon Hybrid 100V | <<locked>> | 94% | 58,320 psi | 90% | 2730 fps | 100% |
| Hodgdon Retumboᴾ | <<locked>> | 100% | 47,369 psi | 73% | 2776 fps | 98.8% |
| Hodgdon Superformance | <<locked>> | 88% | 55,941 psi | 86% | 2795 fps | 99.8% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 36,825 psi | 57% | 1670 fps | 100% |
| IMR 4064 | <<locked>> | 82% | 55,332 psi | 85% | 2657 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 82% | 57,754 psi | 89% | 2697 fps | 99.9% |
| IMR 4350 | <<locked>> | 92% | 58,247 psi | 90% | 2743 fps | 99.8% |
| IMR 4451 Enduron | <<locked>> | 88% | 58,537 psi | 90% | 2733 fps | 99.9% |
| IMR 4831 | <<locked>> | 92% | 57,653 psi | 89% | 2749 fps | 100% |
| IMR 4895 | <<locked>> | 82% | 58,624 psi | 90% | 2743 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 96% | 57,188 psi | 88% | 2736 fps | 98.1% |
| IMR 7828 SSCᴾ | <<locked>> | 100% | 56,898 psi | 88% | 2841 fps | 98.6% |
| Lovex S062 | <<locked>> | 82% | 55,651 psi | 86% | 2648 fps | 100% |
| Lovex S065 | <<locked>> | 88% | 55,492 psi | 85% | 2680 fps | 100% |
| Lovex S070 | <<locked>> | 90% | 56,942 psi | 88% | 2726 fps | 99.9% |
| Lovex S071ᴾ | <<locked>> | 100% | 49,559 psi | 76% | 2635 fps | 99.7% |
| Norma 203B | <<locked>> | 82% | 56,463 psi | 87% | 2703 fps | 100% |
| Norma 204 | <<locked>> | 90% | 55,564 psi | 85% | 2749 fps | 99% |
| Norma MRP | <<locked>> | 96% | 54,882 psi | 84% | 2828 fps | 99.8% |
| Norma URP | <<locked>> | 90% | 55,999 psi | 86% | 2743 fps | 100% |
| Ramshot Big Game | <<locked>> | 82% | 57,159 psi | 88% | 2730 fps | 100% |
| Ramshot Grandᴾ | <<locked>> | 100% | 57,769 psi | 89% | 2864 fps | 99% |
| Ramshot Hunter | <<locked>> | 92% | 58,305 psi | 90% | 2799 fps | 100% |
| Ramshot Magnumᴾ | <<locked>> | 100% | 51,822 psi | 80% | 2743 fps | 99.3% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 37,579 psi | 58% | 1709 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 84% | 57,986 psi | 89% | 2723 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 84% | 55,114 psi | 85% | 2766 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 90% | 57,363 psi | 88% | 2782 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 90% | 55,419 psi | 85% | 2808 fps | 100% |
| ReloadSwiss RS 76ᴾ | <<locked>> | 100% | 47,413 psi | 73% | 2772 fps | 99.5% |
| Rottweil R 902 | <<locked>> | 82% | 57,609 psi | 89% | 2657 fps | 100% |
| Rottweil R 903 | <<locked>> | 86% | 58,291 psi | 90% | 2713 fps | 100% |
| Rottweil R 904 | <<locked>> | 94% | 56,057 psi | 86% | 2726 fps | 98.3% |
| Rottweil R 905 | <<locked>> | 96% | 56,971 psi | 88% | 2785 fps | 99.4% |
| Rottweil R 907 | <<locked>> | 88% | 57,145 psi | 88% | 2710 fps | 99.7% |
| Shooters World Long Rifle | <<locked>> | 88% | 55,492 psi | 85% | 2680 fps | 100% |
| Shooters World Precision | <<locked>> | 82% | 55,651 psi | 86% | 2648 fps | 100% |
| Shooters World SW4350 | <<locked>> | 90% | 56,942 psi | 88% | 2726 fps | 99.9% |
| SNPE Vectan SP 11 | <<locked>> | 84% | 56,057 psi | 86% | 2720 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 86% | 58,595 psi | 90% | 2589 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 90% | 58,537 psi | 90% | 2687 fps | 99.9% |
| SNPE Vectan Tubal 8000 | <<locked>> | 96% | 56,507 psi | 87% | 2782 fps | 99.3% |
| Somchem S355 | <<locked>> | 86% | 57,914 psi | 89% | 2707 fps | 100% |
| Somchem S361 | <<locked>> | 94% | 57,885 psi | 89% | 2726 fps | 98% |
| Somchem S365 | <<locked>> | 92% | 55,738 psi | 86% | 2743 fps | 100% |
| Somchem S385 | <<locked>> | 96% | 57,595 psi | 89% | 2762 fps | 99.7% |
| Vihtavuori N135 | <<locked>> | 82% | 58,291 psi | 90% | 2615 fps | 100% |
| Vihtavuori N140 | <<locked>> | 82% | 58,059 psi | 89% | 2628 fps | 100% |
| Vihtavuori N150 | <<locked>> | 86% | 55,738 psi | 86% | 2635 fps | 100% |
| Vihtavuori N160 | <<locked>> | 90% | 58,030 psi | 89% | 2736 fps | 100% |
| Vihtavuori N165ᴾ | <<locked>> | 100% | 56,884 psi | 88% | 2740 fps | 99.5% |
| Vihtavuori N540 | <<locked>> | 82% | 56,376 psi | 87% | 2631 fps | 100% |
| Vihtavuori N550 | <<locked>> | 90% | 57,087 psi | 88% | 2743 fps | 100% |
| Vihtavuori N555 | <<locked>> | 98% | 58,566 psi | 90% | 2805 fps | 100% |
| Vihtavuori N560 | <<locked>> | 96% | 54,998 psi | 85% | 2822 fps | 97.9% |
| Vihtavuori N565ᴾ | <<locked>> | 100% | 50,430 psi | 78% | 2736 fps | 97.3% |
| Winchester 6.5 StaBALL | <<locked>> | 90% | 57,319 psi | 88% | 2700 fps | 100% |
| Winchester 760 | <<locked>> | 88% | 55,811 psi | 86% | 2759 fps | 99.8% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 52,170 psi | 80% | 2858 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 98% | 57,566 psi | 89% | 2756 fps | 99.3% |
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 2700 | <<locked>> | 80% | 52,939 psi | 81% | 2615 fps | 99.2% |
| Accurate 3100 | <<locked>> | 80% | 30,356 psi | 47% | 2254 fps | 95.3% |
| Accurate 4064 | <<locked>> | 80% | 52,953 psi | 81% | 2598 fps | 100% |
| Accurate 4350 | <<locked>> | 80% | 41,046 psi | 63% | 2500 fps | 99.6% |
| Accurate MAGPRO | 59.7 gr | 92% | 46,659 psi | 72% | 2684 fps | 95.4% |
| ADI AR 2208 | <<locked>> | 80% | 49,385 psi | 76% | 2579 fps | 100% |
| ADI AR 2209 | <<locked>> | 84% | 39,276 psi | 60% | 2480 fps | 95.6% |
| ADI AR 2213 | <<locked>> | 90% | 42,801 psi | 66% | 2579 fps | 95.2% |
| ADI AR 2225 | <<locked>> | 96% | 33,808 psi | 52% | 2431 fps | 95.4% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 50,401 psi | 78% | 2605 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 80% | 53,708 psi | 83% | 2671 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 80% | 39,566 psi | 61% | 2507 fps | 99.7% |
| Alliant Reloder-17 | <<locked>> | 80% | 44,962 psi | 69% | 2618 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 84% | 39,146 psi | 60% | 2477 fps | 95.7% |
| Alliant Reloder-22 | <<locked>> | 86% | 36,999 psi | 57% | 2470 fps | 95.1% |
| Alliant Reloder-23 | <<locked>> | 80% | 29,211 psi | 45% | 2283 fps | 98.4% |
| Alliant Reloder-25 | <<locked>> | 84% | 29,066 psi | 45% | 2293 fps | 95.1% |
| Alliant Reloder-26 | <<locked>> | 80% | 31,285 psi | 48% | 2395 fps | 97.2% |
| Baschieri & Pellagri 109 | <<locked>> | 98% | 54,621 psi | 84% | 2717 fps | 95% |
| Bofors RP15 | <<locked>> | 90% | 39,175 psi | 60% | 2520 fps | 95.7% |
| Bofors RP3 | <<locked>> | 80% | 50,923 psi | 78% | 2615 fps | 100% |
| Bofors RP30 | <<locked>> | 98% | 41,524 psi | 64% | 2602 fps | 95.8% |
| Bofors RP5 | <<locked>> | 86% | 36,999 psi | 57% | 2470 fps | 95.1% |
| Bofors RP7 | <<locked>> | 80% | 44,541 psi | 69% | 2507 fps | 98.1% |
| Hodgdon H1000 | <<locked>> | 96% | 41,800 psi | 64% | 2559 fps | 95.8% |
| Hodgdon H380 | <<locked>> | 80% | 50,995 psi | 78% | 2631 fps | 100% |
| Hodgdon H414 | <<locked>> | 80% | 42,670 psi | 66% | 2539 fps | 98.2% |
| Hodgdon H4350 | <<locked>> | 80% | 45,585 psi | 70% | 2559 fps | 97.7% |
| Hodgdon H4831 | <<locked>> | 90% | 45,629 psi | 70% | 2585 fps | 95.4% |
| Hodgdon H4831 SC | <<locked>> | 90% | 44,889 psi | 69% | 2572 fps | 95.2% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 37,231 psi | 57% | 2402 fps | 99.9% |
| Hodgdon Retumbo | <<locked>> | 92% | 36,622 psi | 56% | 2533 fps | 95.3% |
| Hodgdon Superformance | <<locked>> | 80% | 41,713 psi | 64% | 2559 fps | 97.8% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,601 psi | 42% | 1493 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 51,953 psi | 80% | 2608 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 80% | 54,056 psi | 83% | 2641 fps | 99.7% |
| IMR 4350 | <<locked>> | 80% | 40,030 psi | 62% | 2441 fps | 97.1% |
| IMR 4451 Enduron | <<locked>> | 80% | 45,876 psi | 71% | 2533 fps | 98.7% |
| IMR 4831 | <<locked>> | 80% | 39,117 psi | 60% | 2448 fps | 99.4% |
| IMR 4895 | <<locked>> | 80% | 55,129 psi | 85% | 2697 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 88% | 44,759 psi | 69% | 2533 fps | 95.4% |
| IMR 7828 SSC | <<locked>> | 92% | 43,627 psi | 67% | 2612 fps | 95.6% |
| Lovex S062 | <<locked>> | 80% | 52,301 psi | 80% | 2602 fps | 100% |
| Lovex S065 | <<locked>> | 80% | 43,410 psi | 67% | 2487 fps | 99.2% |
| Lovex S070 | <<locked>> | 80% | 41,582 psi | 64% | 2470 fps | 98.1% |
| Lovex S071 | <<locked>> | 84% | 29,689 psi | 46% | 2238 fps | 95% |
| Norma 203B | <<locked>> | 80% | 53,069 psi | 82% | 2657 fps | 100% |
| Norma 204 | <<locked>> | 80% | 39,697 psi | 61% | 2467 fps | 95.6% |
| Norma MRP | 52.3 gr | 82% | 33,837 psi | 52% | 2425 fps | 95.4% |
| Norma URP | <<locked>> | 80% | 40,422 psi | 62% | 2487 fps | 99.5% |
| Ramshot Big Game | <<locked>> | 80% | 53,461 psi | 82% | 2677 fps | 100% |
| Ramshot Grand | <<locked>> | 90% | 40,553 psi | 62% | 2559 fps | 95% |
| Ramshot Hunter | <<locked>> | 80% | 39,378 psi | 61% | 2484 fps | 98.2% |
| Ramshot Magnum | <<locked>> | 90% | 35,955 psi | 55% | 2444 fps | 95.4% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 28,123 psi | 43% | 1529 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 50,836 psi | 78% | 2618 fps | 99.7% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 47,761 psi | 73% | 2661 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 40,741 psi | 63% | 2516 fps | 99.4% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 39,102 psi | 60% | 2526 fps | 99.1% |
| ReloadSwiss RS 76 | <<locked>> | 92% | 35,897 psi | 55% | 2516 fps | 96.3% |
| Rottweil R 902 | <<locked>> | 80% | 54,128 psi | 83% | 2612 fps | 100% |
| Rottweil R 903 | <<locked>> | 80% | 47,906 psi | 74% | 2566 fps | 100% |
| Rottweil R 904 | <<locked>> | 86% | 43,569 psi | 67% | 2516 fps | 95.7% |
| Rottweil R 905 | <<locked>> | 84% | 38,319 psi | 59% | 2461 fps | 95.6% |
| Rottweil R 907 | <<locked>> | 80% | 44,541 psi | 69% | 2507 fps | 98.1% |
| Shooters World Long Rifle | <<locked>> | 80% | 43,410 psi | 67% | 2487 fps | 99.2% |
| Shooters World Precision | <<locked>> | 80% | 52,301 psi | 80% | 2602 fps | 100% |
| Shooters World SW4350 | <<locked>> | 80% | 41,582 psi | 64% | 2470 fps | 98.1% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 49,226 psi | 76% | 2621 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 48,689 psi | 75% | 2461 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 42,496 psi | 65% | 2434 fps | 98.2% |
| SNPE Vectan Tubal 8000 | <<locked>> | 84% | 37,985 psi | 58% | 2457 fps | 95.5% |
| Somchem S355 | <<locked>> | 80% | 48,051 psi | 74% | 2566 fps | 100% |
| Somchem S361 | <<locked>> | 86% | 44,251 psi | 68% | 2507 fps | 95% |
| Somchem S365 | <<locked>> | 80% | 37,130 psi | 57% | 2451 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 34,200 psi | 53% | 2343 fps | 95% |
| Vihtavuori N135 | <<locked>> | 80% | 54,694 psi | 84% | 2569 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 54,621 psi | 84% | 2585 fps | 100% |
| Vihtavuori N150 | <<locked>> | 80% | 45,847 psi | 71% | 2493 fps | 100% |
| Vihtavuori N160 | <<locked>> | 80% | 41,989 psi | 65% | 2487 fps | 99.6% |
| Vihtavuori N165 | <<locked>> | 86% | 35,882 psi | 55% | 2375 fps | 95.2% |
| Vihtavuori N540 | <<locked>> | 80% | 52,794 psi | 81% | 2582 fps | 100% |
| Vihtavuori N550 | <<locked>> | 80% | 41,249 psi | 63% | 2487 fps | 99.4% |
| Vihtavuori N555 | <<locked>> | 80% | 32,561 psi | 50% | 2356 fps | 98.4% |
| Vihtavuori N560 | 57.4 gr | 90% | 44,860 psi | 69% | 2648 fps | 95.6% |
| Vihtavuori N565 | <<locked>> | 96% | 44,077 psi | 68% | 2621 fps | 95.6% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 40,872 psi | 63% | 2457 fps | 100% |
| Winchester 760 | <<locked>> | 80% | 42,902 psi | 66% | 2546 fps | 98.3% |
| Winchester StaBALL HD | <<locked>> | 80% | 25,889 psi | 40% | 2277 fps | 98.1% |
| Winchester Supreme 780 | <<locked>> | 86% | 38,087 psi | 59% | 2428 fps | 95.3% |
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 90 powders for .280 Ackley Improved loaded with the .284 | 170gr | Sierra RN Prohunter. Alliant Reloder-26 delivers the highest muzzle velocity at 2,867 fps; across all powders the maximum-charge window runs from 1,670 fps to 2,867 fps. ADI AR 2225 gives the best case fill at 100 %, and 90 of the 90 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (448 MPa), the top charges use 57–90 %, leaving at least 10 % headroom. The 170.0 gr projectile in 0.284" calls for a 1:12.5 twist; slower twists will usually not stabilise this weight. ADI AR 2225, Alliant Reloder-23, Alliant Reloder-25 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. Norma MRP, Vihtavuori N560, Accurate MAGPRO rank at the top here: for .280 Ackley Improved with the .284 | 170gr | Sierra RN Prohunter 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.