Load Specifications
Load data in caliber .280 Ackley Improved with .285 | 173gr | Prvi Partizan SP bullet and 87 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 Alliant Reloder-26.
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% | 57,203 psi | 88% | 2657 fps | 99.7% |
| Accurate 3100 | <<locked>> | 98% | 56,420 psi | 87% | 2713 fps | 100% |
| Accurate 4064 | <<locked>> | 82% | 57,363 psi | 88% | 2631 fps | 100% |
| Accurate 4350 | <<locked>> | 90% | 58,436 psi | 90% | 2749 fps | 100% |
| Accurate MAGPRO | <<locked>> | 96% | 54,839 psi | 84% | 2802 fps | 97.5% |
| ADI AR 2208 | <<locked>> | 84% | 56,768 psi | 87% | 2664 fps | 100% |
| ADI AR 2209 | <<locked>> | 94% | 55,477 psi | 85% | 2749 fps | 99.2% |
| ADI AR 2213 | <<locked>> | 98% | 56,753 psi | 87% | 2805 fps | 98.6% |
| ADI AR 2217ᴾ | <<locked>> | 100% | 44,324 psi | 68% | 2585 fps | 96.2% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 39,233 psi | 60% | 2549 fps | 98% |
| Alliant Reloder- TS 15.5 | <<locked>> | 84% | 57,725 psi | 89% | 2684 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 82% | 57,798 psi | 89% | 2707 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 90% | 55,492 psi | 85% | 2749 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 86% | 56,855 psi | 87% | 2769 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 96% | 58,465 psi | 90% | 2789 fps | 99.5% |
| Alliant Reloder-22 | <<locked>> | 98% | 56,246 psi | 87% | 2802 fps | 99.4% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 57,000 psi | 88% | 2769 fps | 100% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 49,284 psi | 76% | 2723 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 96% | 57,551 psi | 89% | 2864 fps | 100% |
| Bofors RP15ᴾ | <<locked>> | 100% | 55,100 psi | 85% | 2782 fps | 99.2% |
| Bofors RP3 | <<locked>> | 82% | 55,259 psi | 85% | 2654 fps | 100% |
| Bofors RP30ᴾ | <<locked>> | 100% | 45,368 psi | 70% | 2657 fps | 97.2% |
| Bofors RP5 | <<locked>> | 98% | 56,246 psi | 87% | 2802 fps | 99.4% |
| Bofors RP7 | <<locked>> | 88% | 57,769 psi | 89% | 2700 fps | 99.8% |
| Hodgdon H1000ᴾ | <<locked>> | 100% | 48,863 psi | 75% | 2674 fps | 98% |
| Hodgdon H380 | <<locked>> | 82% | 55,274 psi | 85% | 2671 fps | 100% |
| Hodgdon H414 | <<locked>> | 88% | 56,550 psi | 87% | 2749 fps | 99.9% |
| Hodgdon H4350 | <<locked>> | 86% | 56,144 psi | 86% | 2713 fps | 99.4% |
| Hodgdon H4831 | <<locked>> | 96% | 56,753 psi | 87% | 2746 fps | 98% |
| Hodgdon H4831 SC | <<locked>> | 96% | 55,840 psi | 86% | 2733 fps | 97.9% |
| Hodgdon Hybrid 100V | <<locked>> | 92% | 55,767 psi | 86% | 2677 fps | 100% |
| Hodgdon Retumboᴾ | <<locked>> | 100% | 48,341 psi | 74% | 2776 fps | 99.2% |
| Hodgdon Superformance | <<locked>> | 88% | 57,000 psi | 88% | 2789 fps | 99.9% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 36,738 psi | 57% | 1657 fps | 100% |
| IMR 4064 | <<locked>> | 82% | 56,246 psi | 87% | 2648 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 82% | 58,349 psi | 90% | 2684 fps | 99.9% |
| IMR 4350 | <<locked>> | 90% | 55,434 psi | 85% | 2684 fps | 99.7% |
| IMR 4451 Enduron | <<locked>> | 86% | 55,999 psi | 86% | 2674 fps | 99.8% |
| IMR 4831 | <<locked>> | 92% | 58,726 psi | 90% | 2740 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 96% | 58,146 psi | 89% | 2733 fps | 98.4% |
| IMR 7828 SSCᴾ | <<locked>> | 100% | 58,015 psi | 89% | 2835 fps | 98.9% |
| Lovex S062 | <<locked>> | 82% | 56,579 psi | 87% | 2638 fps | 100% |
| Lovex S065 | <<locked>> | 88% | 56,130 psi | 86% | 2671 fps | 100% |
| Lovex S070 | <<locked>> | 90% | 57,609 psi | 89% | 2713 fps | 100% |
| Lovex S071ᴾ | <<locked>> | 100% | 50,299 psi | 77% | 2625 fps | 99.8% |
| Norma 203B | <<locked>> | 82% | 57,145 psi | 88% | 2694 fps | 100% |
| Norma 204 | <<locked>> | 90% | 56,318 psi | 87% | 2740 fps | 99.2% |
| Norma MRP | <<locked>> | 96% | 56,072 psi | 86% | 2825 fps | 99.9% |
| Norma URP | <<locked>> | 90% | 56,739 psi | 87% | 2730 fps | 100% |
| Ramshot Big Game | <<locked>> | 82% | 58,146 psi | 89% | 2720 fps | 100% |
| Ramshot Grand | <<locked>> | 98% | 54,752 psi | 84% | 2799 fps | 98.7% |
| Ramshot Hunter | <<locked>> | 90% | 55,535 psi | 85% | 2736 fps | 100% |
| Ramshot Magnumᴾ | <<locked>> | 100% | 52,910 psi | 81% | 2740 fps | 99.5% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 37,507 psi | 58% | 1696 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 84% | 58,639 psi | 90% | 2710 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 84% | 56,289 psi | 87% | 2756 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 90% | 58,450 psi | 90% | 2776 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 90% | 56,550 psi | 87% | 2802 fps | 100% |
| ReloadSwiss RS 76ᴾ | <<locked>> | 100% | 48,385 psi | 74% | 2769 fps | 99.7% |
| Rottweil R 902 | <<locked>> | 82% | 58,247 psi | 90% | 2644 fps | 100% |
| Rottweil R 903 | <<locked>> | 84% | 55,419 psi | 85% | 2654 fps | 100% |
| Rottweil R 904 | <<locked>> | 94% | 56,985 psi | 88% | 2720 fps | 98.6% |
| Rottweil R 905 | <<locked>> | 96% | 58,044 psi | 89% | 2782 fps | 99.6% |
| Rottweil R 907 | <<locked>> | 88% | 57,769 psi | 89% | 2700 fps | 99.8% |
| Shooters World Long Rifle | <<locked>> | 88% | 56,130 psi | 86% | 2671 fps | 100% |
| Shooters World Precision | <<locked>> | 82% | 56,579 psi | 87% | 2638 fps | 100% |
| Shooters World SW4350 | <<locked>> | 90% | 57,609 psi | 89% | 2713 fps | 100% |
| SNPE Vectan SP 11 | <<locked>> | 84% | 56,768 psi | 87% | 2707 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 84% | 55,898 psi | 86% | 2536 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 88% | 55,564 psi | 85% | 2628 fps | 99.8% |
| SNPE Vectan Tubal 8000 | <<locked>> | 96% | 57,580 psi | 89% | 2776 fps | 99.5% |
| Somchem S355 | <<locked>> | 84% | 55,390 psi | 85% | 2651 fps | 100% |
| Somchem S361 | <<locked>> | 92% | 54,824 psi | 84% | 2661 fps | 97.7% |
| Somchem S365 | <<locked>> | 92% | 56,942 psi | 88% | 2736 fps | 100% |
| Somchem S385 | <<locked>> | 96% | 58,639 psi | 90% | 2756 fps | 99.8% |
| Vihtavuori N150 | <<locked>> | 86% | 56,391 psi | 87% | 2621 fps | 100% |
| Vihtavuori N160 | <<locked>> | 90% | 58,769 psi | 90% | 2723 fps | 100% |
| Vihtavuori N165ᴾ | <<locked>> | 100% | 57,943 psi | 89% | 2733 fps | 99.7% |
| Vihtavuori N540 | <<locked>> | 82% | 57,000 psi | 88% | 2615 fps | 100% |
| Vihtavuori N550 | <<locked>> | 90% | 57,856 psi | 89% | 2730 fps | 100% |
| Vihtavuori N555 | <<locked>> | 96% | 56,057 psi | 86% | 2749 fps | 100% |
| Vihtavuori N560 | <<locked>> | 96% | 56,130 psi | 86% | 2818 fps | 98.3% |
| Vihtavuori N565ᴾ | <<locked>> | 100% | 51,517 psi | 79% | 2736 fps | 97.7% |
| Winchester 6.5 StaBALL | <<locked>> | 90% | 58,363 psi | 90% | 2690 fps | 100% |
| Winchester 760 | <<locked>> | 88% | 56,869 psi | 87% | 2756 fps | 99.9% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 53,664 psi | 83% | 2851 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 98% | 58,639 psi | 90% | 2749 fps | 99.5% |
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% | 53,809 psi | 83% | 2608 fps | 99.4% |
| Accurate 3100 | <<locked>> | 80% | 30,879 psi | 48% | 2251 fps | 95.8% |
| Accurate 4064 | <<locked>> | 80% | 53,925 psi | 83% | 2589 fps | 100% |
| Accurate 4350 | <<locked>> | 80% | 41,742 psi | 64% | 2490 fps | 99.7% |
| Accurate MAGPRO | <<locked>> | 90% | 44,454 psi | 68% | 2625 fps | 95% |
| ADI AR 2208 | <<locked>> | 80% | 50,183 psi | 77% | 2572 fps | 100% |
| ADI AR 2209 | <<locked>> | 82% | 37,550 psi | 58% | 2425 fps | 95.3% |
| ADI AR 2213 | <<locked>> | 90% | 43,395 psi | 67% | 2575 fps | 95.7% |
| ADI AR 2217 | <<locked>> | 98% | 41,510 psi | 64% | 2530 fps | 95.2% |
| ADI AR 2225 | <<locked>> | 94% | 32,460 psi | 50% | 2375 fps | 95% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 51,039 psi | 79% | 2592 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 80% | 54,375 psi | 84% | 2657 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 80% | 40,147 psi | 62% | 2500 fps | 99.8% |
| Alliant Reloder-17 | <<locked>> | 80% | 45,963 psi | 71% | 2612 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 82% | 37,275 psi | 57% | 2418 fps | 95.3% |
| Alliant Reloder-22 | <<locked>> | 86% | 37,811 psi | 58% | 2470 fps | 95.6% |
| Alliant Reloder-23 | <<locked>> | 80% | 29,849 psi | 46% | 2283 fps | 98.8% |
| Alliant Reloder-25 | <<locked>> | 84% | 29,660 psi | 46% | 2293 fps | 95.8% |
| Alliant Reloder-26 | 52.7 gr | 80% | 32,039 psi | 49% | 2395 fps | 97.7% |
| Bofors RP15 | <<locked>> | 88% | 37,333 psi | 57% | 2461 fps | 95.3% |
| Bofors RP3 | <<locked>> | 80% | 51,851 psi | 80% | 2608 fps | 100% |
| Bofors RP30 | <<locked>> | 96% | 39,610 psi | 61% | 2543 fps | 95.4% |
| Bofors RP5 | <<locked>> | 86% | 37,811 psi | 58% | 2470 fps | 95.6% |
| Bofors RP7 | <<locked>> | 80% | 45,078 psi | 69% | 2497 fps | 98.4% |
| Hodgdon H1000 | <<locked>> | 94% | 39,958 psi | 61% | 2500 fps | 95.4% |
| Hodgdon H380 | <<locked>> | 80% | 51,909 psi | 80% | 2625 fps | 100% |
| Hodgdon H414 | <<locked>> | 80% | 43,526 psi | 67% | 2536 fps | 98.6% |
| Hodgdon H4350 | <<locked>> | 80% | 46,398 psi | 71% | 2552 fps | 98.1% |
| Hodgdon H4831 | <<locked>> | 88% | 43,613 psi | 67% | 2530 fps | 95.1% |
| Hodgdon H4831 SC | <<locked>> | 90% | 45,484 psi | 70% | 2562 fps | 95.7% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 37,826 psi | 58% | 2392 fps | 99.9% |
| Hodgdon Retumbo | <<locked>> | 92% | 37,391 psi | 58% | 2536 fps | 96% |
| Hodgdon Superformance | <<locked>> | 80% | 42,395 psi | 65% | 2552 fps | 98.1% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,543 psi | 42% | 1480 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 52,837 psi | 81% | 2598 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 80% | 54,911 psi | 84% | 2635 fps | 99.8% |
| IMR 4350 | <<locked>> | 80% | 40,770 psi | 63% | 2438 fps | 97.5% |
| IMR 4451 Enduron | <<locked>> | 80% | 46,412 psi | 71% | 2523 fps | 98.9% |
| IMR 4831 | <<locked>> | 80% | 39,929 psi | 61% | 2444 fps | 99.6% |
| IMR 4955 Enduron | <<locked>> | 86% | 42,598 psi | 66% | 2474 fps | 95% |
| IMR 7828 SSC | <<locked>> | 90% | 41,698 psi | 64% | 2552 fps | 95.3% |
| Lovex S062 | <<locked>> | 80% | 53,185 psi | 82% | 2592 fps | 100% |
| Lovex S065 | <<locked>> | 80% | 44,193 psi | 68% | 2480 fps | 99.4% |
| Lovex S070 | <<locked>> | 80% | 42,395 psi | 65% | 2464 fps | 98.5% |
| Lovex S071 | <<locked>> | 84% | 30,400 psi | 47% | 2238 fps | 95.6% |
| Norma 203B | <<locked>> | 80% | 53,737 psi | 83% | 2644 fps | 100% |
| Norma 204 | <<locked>> | 80% | 40,248 psi | 62% | 2461 fps | 96.1% |
| Norma MRP | 52.4 gr | 82% | 34,374 psi | 53% | 2421 fps | 95.9% |
| Norma URP | <<locked>> | 80% | 41,263 psi | 63% | 2484 fps | 99.7% |
| Ramshot Big Game | <<locked>> | 80% | 54,418 psi | 84% | 2671 fps | 100% |
| Ramshot Grand | <<locked>> | 90% | 41,423 psi | 64% | 2559 fps | 95.6% |
| Ramshot Hunter | <<locked>> | 80% | 39,958 psi | 61% | 2474 fps | 98.5% |
| Ramshot Magnum | <<locked>> | 88% | 34,229 psi | 53% | 2385 fps | 95% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 28,079 psi | 43% | 1512 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 51,706 psi | 80% | 2608 fps | 99.8% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 48,805 psi | 75% | 2654 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 41,597 psi | 64% | 2513 fps | 99.6% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 39,914 psi | 61% | 2523 fps | 99.4% |
| ReloadSwiss RS 76 | <<locked>> | 90% | 34,084 psi | 52% | 2451 fps | 95.7% |
| Rottweil R 902 | <<locked>> | 80% | 55,042 psi | 85% | 2602 fps | 100% |
| Rottweil R 903 | <<locked>> | 80% | 48,805 psi | 75% | 2559 fps | 100% |
| Rottweil R 904 | <<locked>> | 84% | 41,437 psi | 64% | 2457 fps | 95.3% |
| Rottweil R 905 | <<locked>> | 82% | 36,666 psi | 56% | 2405 fps | 95.3% |
| Rottweil R 907 | <<locked>> | 80% | 45,078 psi | 69% | 2497 fps | 98.4% |
| Shooters World Long Rifle | <<locked>> | 80% | 44,193 psi | 68% | 2480 fps | 99.4% |
| Shooters World Precision | <<locked>> | 80% | 53,185 psi | 82% | 2592 fps | 100% |
| Shooters World SW4350 | <<locked>> | 80% | 42,395 psi | 65% | 2464 fps | 98.5% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 49,879 psi | 77% | 2608 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 49,530 psi | 76% | 2454 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 43,018 psi | 66% | 2425 fps | 98.4% |
| SNPE Vectan Tubal 8000 | <<locked>> | 82% | 36,318 psi | 56% | 2402 fps | 95.1% |
| Somchem S355 | <<locked>> | 80% | 48,907 psi | 75% | 2556 fps | 100% |
| Somchem S361 | <<locked>> | 86% | 45,063 psi | 69% | 2500 fps | 95.5% |
| Somchem S365 | <<locked>> | 80% | 38,000 psi | 58% | 2444 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 34,911 psi | 54% | 2343 fps | 95.6% |
| Vihtavuori N150 | <<locked>> | 80% | 46,688 psi | 72% | 2487 fps | 100% |
| Vihtavuori N160 | <<locked>> | 80% | 42,598 psi | 66% | 2480 fps | 99.8% |
| Vihtavuori N165 | <<locked>> | 86% | 36,651 psi | 56% | 2375 fps | 95.8% |
| Vihtavuori N540 | <<locked>> | 80% | 53,650 psi | 83% | 2572 fps | 100% |
| Vihtavuori N550 | <<locked>> | 80% | 42,076 psi | 65% | 2484 fps | 99.6% |
| Vihtavuori N555 | <<locked>> | 80% | 33,344 psi | 51% | 2352 fps | 98.8% |
| Vihtavuori N560 | 56.3 gr | 88% | 42,772 psi | 66% | 2585 fps | 95.2% |
| Vihtavuori N565 | <<locked>> | 94% | 42,250 psi | 65% | 2569 fps | 95.3% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 41,423 psi | 64% | 2444 fps | 100% |
| Winchester 760 | <<locked>> | 80% | 43,772 psi | 67% | 2543 fps | 98.6% |
| Winchester StaBALL HD | <<locked>> | 80% | 26,310 psi | 40% | 2277 fps | 98.6% |
| Winchester Supreme 780 | <<locked>> | 86% | 38,856 psi | 60% | 2428 fps | 95.8% |
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 87 powders for .280 Ackley Improved loaded with the .285 | 173gr | Prvi Partizan SP. Alliant Reloder-26 delivers the highest muzzle velocity at 2,864 fps; across all powders the maximum-charge window runs from 1,657 fps to 2,864 fps. ADI AR 2217 gives the best case fill at 100 %, and 87 of the 87 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 173.0 gr projectile in 0.285" calls for a 1:12.5 twist; slower twists will usually not stabilise this weight. ADI AR 2217, ADI AR 2225, Alliant Reloder-23 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, Alliant Reloder-26 rank at the top here: for .280 Ackley Improved with the .285 | 173gr | Prvi Partizan SP 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.