Load Specifications
Bullet Manufacturer:Prvi Partizan
Bullet Weight:158 gr
Bullet Diameter:0.284"
Bullet Length:<<locked>>
Caliber:.280 Ackley Improved load data
Case Length (l3):2.54"
Cartridge Length (C.O.L.):<<locked>>
Case Capacity:74 Grains of Water
Primer Size:Large Rifle (LR)
Barrel Length:24"
Max. allowed Pressure:65,000 psi
Recommended Twist Rate:1:11.0
Load data in caliber .280 Ackley Improved with .284 | 158gr | Prvi Partizan Grom bullet and 100 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% | 55,738 psi | 86% | 2680 fps | 100% |
| Accurate 2700 | <<locked>> | 84% | 56,579 psi | 87% | 2753 fps | 99.1% |
| Accurate 3100ᴾ | <<locked>> | 100% | 54,592 psi | 84% | 2799 fps | 99.8% |
| Accurate 4064 | <<locked>> | 84% | 55,912 psi | 86% | 2733 fps | 100% |
| Accurate 4350 | <<locked>> | 92% | 56,927 psi | 88% | 2848 fps | 100% |
| Accurate MAGPROᴾ | <<locked>> | 100% | 56,753 psi | 87% | 2940 fps | 96.7% |
| ADI AR 2206H | <<locked>> | 82% | 58,160 psi | 89% | 2808 fps | 100% |
| ADI AR 2208 | <<locked>> | 86% | 55,898 psi | 86% | 2766 fps | 100% |
| ADI AR 2209 | <<locked>> | 98% | 57,479 psi | 88% | 2887 fps | 98.7% |
| ADI AR 2213ᴾ | <<locked>> | 100% | 55,143 psi | 85% | 2881 fps | 97.3% |
| Alliant Power Pro 2000-MR | <<locked>> | 82% | 55,376 psi | 85% | 2890 fps | 100% |
| Alliant Reloder- TS 15.5 | <<locked>> | 86% | 56,826 psi | 87% | 2789 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 84% | 56,913 psi | 88% | 2808 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 94% | 57,435 psi | 88% | 2900 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 88% | 54,897 psi | 84% | 2867 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 98% | 56,956 psi | 88% | 2877 fps | 98.7% |
| Alliant Reloder-22ᴾ | <<locked>> | 100% | 54,070 psi | 83% | 2877 fps | 98.4% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 51,285 psi | 79% | 2815 fps | 100% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 44,411 psi | 68% | 2740 fps | 99.3% |
| Alliant Reloder-26 | <<locked>> | 98% | 54,882 psi | 84% | 2949 fps | 100% |
| Baschieri & Pellagri 107 | <<locked>> | 82% | 58,407 psi | 90% | 2831 fps | 100% |
| Bofors RP15ᴾ | <<locked>> | 100% | 49,559 psi | 76% | 2802 fps | 97.5% |
| Bofors RP3 | <<locked>> | 86% | 57,769 psi | 89% | 2805 fps | 100% |
| Bofors RP5ᴾ | <<locked>> | 100% | 54,070 psi | 83% | 2877 fps | 98.4% |
| Bofors RP7 | <<locked>> | 90% | 56,811 psi | 87% | 2792 fps | 99.2% |
| Hodgdon H380 | <<locked>> | 86% | 58,233 psi | 90% | 2828 fps | 100% |
| Hodgdon H414 | <<locked>> | 90% | 55,303 psi | 85% | 2844 fps | 99.4% |
| Hodgdon H4350 | <<locked>> | 90% | 58,450 psi | 90% | 2854 fps | 99% |
| Hodgdon H4831 | <<locked>> | 98% | 55,390 psi | 85% | 2828 fps | 96.7% |
| Hodgdon H4831 SCᴾ | <<locked>> | 100% | 57,899 psi | 89% | 2867 fps | 97.2% |
| Hodgdon Hybrid 100V | <<locked>> | 96% | 57,827 psi | 89% | 2822 fps | 100% |
| Hodgdon LEVERevolution | <<locked>> | 82% | 55,579 psi | 86% | 2805 fps | 100% |
| Hodgdon Retumboᴾ | <<locked>> | 100% | 43,584 psi | 67% | 2772 fps | 96.8% |
| Hodgdon Superformance | <<locked>> | 90% | 55,216 psi | 85% | 2877 fps | 99.3% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 36,463 psi | 56% | 1719 fps | 100% |
| Hodgdon VARGET | <<locked>> | 82% | 56,434 psi | 87% | 2769 fps | 100% |
| IMR 4064 | <<locked>> | 84% | 55,274 psi | 85% | 2749 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 84% | 57,943 psi | 89% | 2785 fps | 99.6% |
| IMR 4350 | <<locked>> | 94% | 58,088 psi | 89% | 2831 fps | 99.4% |
| IMR 4451 Enduron | <<locked>> | 90% | 58,595 psi | 90% | 2822 fps | 99.6% |
| IMR 4831 | <<locked>> | 94% | 57,101 psi | 88% | 2835 fps | 100% |
| IMR 4895 | <<locked>> | 84% | 58,363 psi | 90% | 2838 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 98% | 56,826 psi | 87% | 2815 fps | 97.1% |
| IMR 7828 SSCᴾ | <<locked>> | 100% | 52,547 psi | 81% | 2854 fps | 96.9% |
| Lovex S060 | <<locked>> | 82% | 56,956 psi | 88% | 2736 fps | 100% |
| Lovex S062 | <<locked>> | 84% | 55,753 psi | 86% | 2746 fps | 100% |
| Lovex S065 | <<locked>> | 92% | 58,566 psi | 90% | 2815 fps | 100% |
| Lovex S070 | <<locked>> | 92% | 56,681 psi | 87% | 2812 fps | 99.6% |
| Lovex S071ᴾ | <<locked>> | 100% | 45,310 psi | 70% | 2651 fps | 98.7% |
| Norma 201 | <<locked>> | 82% | 57,087 psi | 88% | 2753 fps | 100% |
| Norma 202 | <<locked>> | 82% | 57,638 psi | 89% | 2746 fps | 100% |
| Norma 203B | <<locked>> | 84% | 56,202 psi | 86% | 2795 fps | 100% |
| Norma 204 | <<locked>> | 92% | 55,259 psi | 85% | 2828 fps | 98.3% |
| Norma MRPᴾ | <<locked>> | 100% | 57,624 psi | 89% | 2966 fps | 99.7% |
| Norma URP | <<locked>> | 92% | 55,492 psi | 85% | 2831 fps | 100% |
| Ramshot Big Game | <<locked>> | 84% | 57,072 psi | 88% | 2825 fps | 100% |
| Ramshot Grandᴾ | <<locked>> | 100% | 53,113 psi | 82% | 2871 fps | 97.3% |
| Ramshot Hunter | <<locked>> | 94% | 57,725 psi | 89% | 2884 fps | 99.9% |
| Ramshot Magnumᴾ | <<locked>> | 100% | 47,224 psi | 73% | 2746 fps | 97.8% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 37,159 psi | 57% | 1762 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 86% | 57,885 psi | 89% | 2808 fps | 99.8% |
| ReloadSwiss RS 52 | <<locked>> | 82% | 58,146 psi | 89% | 2877 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 88% | 58,363 psi | 90% | 2910 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 92% | 56,608 psi | 87% | 2867 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 92% | 55,085 psi | 85% | 2897 fps | 100% |
| ReloadSwiss RS 76ᴾ | <<locked>> | 100% | 43,555 psi | 67% | 2766 fps | 97.8% |
| Rottweil R 902 | <<locked>> | 84% | 57,566 psi | 89% | 2753 fps | 100% |
| Rottweil R 903 | <<locked>> | 88% | 57,928 psi | 89% | 2805 fps | 100% |
| Rottweil R 904 | <<locked>> | 96% | 55,579 psi | 86% | 2802 fps | 97.4% |
| Rottweil R 905 | <<locked>> | 98% | 56,101 psi | 86% | 2861 fps | 98.7% |
| Rottweil R 907 | <<locked>> | 90% | 56,811 psi | 87% | 2792 fps | 99.2% |
| Shooters World Long Rifle | <<locked>> | 92% | 58,566 psi | 90% | 2815 fps | 100% |
| Shooters World Precision | <<locked>> | 84% | 55,753 psi | 86% | 2746 fps | 100% |
| Shooters World SW4350 | <<locked>> | 92% | 56,681 psi | 87% | 2812 fps | 99.6% |
| SNPE Vectan SP 11 | <<locked>> | 86% | 55,666 psi | 86% | 2812 fps | 100% |
| SNPE Vectan SP 9 | <<locked>> | 82% | 56,550 psi | 87% | 2779 fps | 100% |
| SNPE Vectan Tubal 3000 | <<locked>> | 82% | 57,537 psi | 89% | 2677 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 88% | 58,769 psi | 90% | 2684 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 92% | 58,624 psi | 90% | 2772 fps | 99.6% |
| SNPE Vectan Tubal 8000 | <<locked>> | 98% | 55,622 psi | 86% | 2858 fps | 98.6% |
| Somchem S335 | <<locked>> | 82% | 57,479 psi | 88% | 2680 fps | 100% |
| Somchem S355 | <<locked>> | 88% | 57,667 psi | 89% | 2795 fps | 100% |
| Somchem S361 | <<locked>> | 96% | 57,377 psi | 88% | 2799 fps | 97% |
| Somchem S365 | <<locked>> | 96% | 58,595 psi | 90% | 2881 fps | 100% |
| Somchem S385 | <<locked>> | 98% | 56,768 psi | 87% | 2838 fps | 99.2% |
| Vihtavuori N133 | <<locked>> | 82% | 58,102 psi | 89% | 2661 fps | 100% |
| Vihtavuori N135 | <<locked>> | 84% | 58,088 psi | 89% | 2710 fps | 100% |
| Vihtavuori N140 | <<locked>> | 84% | 58,320 psi | 90% | 2726 fps | 100% |
| Vihtavuori N150 | <<locked>> | 88% | 55,535 psi | 85% | 2723 fps | 100% |
| Vihtavuori N160 | <<locked>> | 92% | 57,653 psi | 89% | 2825 fps | 100% |
| Vihtavuori N165ᴾ | <<locked>> | 100% | 52,533 psi | 81% | 2762 fps | 98.5% |
| Vihtavuori N540 | <<locked>> | 84% | 56,318 psi | 87% | 2723 fps | 100% |
| Vihtavuori N550 | <<locked>> | 92% | 56,666 psi | 87% | 2831 fps | 100% |
| Vihtavuori N555ᴾ | <<locked>> | 100% | 57,305 psi | 88% | 2887 fps | 100% |
| Vihtavuori N560ᴾ | <<locked>> | 100% | 57,885 psi | 89% | 2953 fps | 97.5% |
| Winchester 6.5 StaBALL | <<locked>> | 92% | 57,217 psi | 88% | 2789 fps | 100% |
| Winchester 760 | <<locked>> | 90% | 55,303 psi | 85% | 2844 fps | 99.4% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 46,137 psi | 71% | 2871 fps | 100% |
| Winchester StaBALL Match | <<locked>> | 82% | 56,884 psi | 88% | 2789 fps | 100% |
| Winchester Supreme 780ᴾ | <<locked>> | 100% | 57,246 psi | 88% | 2838 fps | 98.6% |
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% | 52,243 psi | 80% | 2635 fps | 100% |
| Accurate 2700 | <<locked>> | 80% | 49,719 psi | 76% | 2644 fps | 98.1% |
| Accurate 3100 | <<locked>> | 86% | 33,866 psi | 52% | 2418 fps | 95.7% |
| Accurate 4064 | <<locked>> | 80% | 49,487 psi | 76% | 2644 fps | 100% |
| Accurate 4350 | <<locked>> | 80% | 37,666 psi | 58% | 2516 fps | 98.5% |
| Accurate MAGPRO | <<locked>> | 98% | 52,808 psi | 81% | 2874 fps | 95.8% |
| ADI AR 2206H | <<locked>> | 80% | 54,665 psi | 84% | 2759 fps | 100% |
| ADI AR 2208 | <<locked>> | 80% | 46,514 psi | 72% | 2618 fps | 99.9% |
| ADI AR 2209 | <<locked>> | 88% | 41,742 psi | 64% | 2612 fps | 95.3% |
| ADI AR 2213 | <<locked>> | 96% | 48,370 psi | 74% | 2762 fps | 95.7% |
| Alliant Power Pro 2000-MR | <<locked>> | 80% | 51,590 psi | 79% | 2831 fps | 100% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 46,978 psi | 72% | 2641 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 80% | 50,198 psi | 77% | 2707 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 80% | 36,782 psi | 57% | 2530 fps | 98.6% |
| Alliant Reloder-17 | <<locked>> | 80% | 41,626 psi | 64% | 2648 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 88% | 41,220 psi | 63% | 2598 fps | 95.2% |
| Alliant Reloder-22 | <<locked>> | 92% | 41,611 psi | 64% | 2654 fps | 95.6% |
| Alliant Reloder-23 | <<locked>> | 80% | 26,992 psi | 42% | 2290 fps | 96.4% |
| Alliant Reloder-25 | <<locked>> | 90% | 32,547 psi | 50% | 2461 fps | 95.6% |
| Alliant Reloder-26 | 53.1 gr | 82% | 30,690 psi | 47% | 2451 fps | 95.7% |
| Baschieri & Pellagri 107 | <<locked>> | 80% | 54,621 psi | 84% | 2779 fps | 100% |
| Bofors RP15 | <<locked>> | 94% | 40,799 psi | 63% | 2635 fps | 95.1% |
| Bofors RP3 | <<locked>> | 80% | 47,311 psi | 73% | 2651 fps | 100% |
| Bofors RP5 | <<locked>> | 92% | 41,611 psi | 64% | 2654 fps | 95.6% |
| Bofors RP7 | <<locked>> | 80% | 41,655 psi | 64% | 2530 fps | 96.5% |
| Hodgdon H380 | <<locked>> | 80% | 47,848 psi | 74% | 2667 fps | 99.7% |
| Hodgdon H414 | <<locked>> | 80% | 39,668 psi | 61% | 2562 fps | 96.6% |
| Hodgdon H4350 | <<locked>> | 80% | 42,438 psi | 65% | 2579 fps | 96% |
| Hodgdon H4831 | <<locked>> | 94% | 48,298 psi | 74% | 2710 fps | 95% |
| Hodgdon H4831 SC | <<locked>> | 96% | 50,734 psi | 78% | 2753 fps | 95.6% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 34,156 psi | 53% | 2421 fps | 99% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 52,170 psi | 80% | 2756 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 98% | 40,886 psi | 63% | 2707 fps | 95.7% |
| Hodgdon Superformance | 53.5 gr | 80% | 38,595 psi | 59% | 2572 fps | 95.8% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,166 psi | 42% | 1535 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 52,982 psi | 82% | 2720 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 48,950 psi | 75% | 2651 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 80% | 51,184 psi | 79% | 2680 fps | 98.9% |
| IMR 4350 | <<locked>> | 80% | 37,449 psi | 58% | 2461 fps | 95.2% |
| IMR 4451 Enduron | <<locked>> | 80% | 42,989 psi | 66% | 2559 fps | 97.3% |
| IMR 4831 | <<locked>> | 80% | 36,216 psi | 56% | 2470 fps | 98.2% |
| IMR 4895 | <<locked>> | 80% | 51,503 psi | 79% | 2736 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 92% | 47,369 psi | 73% | 2657 fps | 95% |
| IMR 7828 SSC | <<locked>> | 96% | 46,064 psi | 71% | 2736 fps | 95.1% |
| Lovex S060 | <<locked>> | 80% | 53,519 psi | 82% | 2687 fps | 100% |
| Lovex S062 | <<locked>> | 80% | 49,182 psi | 76% | 2648 fps | 100% |
| Lovex S065 | <<locked>> | 80% | 40,727 psi | 63% | 2513 fps | 98.1% |
| Lovex S070 | <<locked>> | 80% | 38,899 psi | 60% | 2493 fps | 96.5% |
| Lovex S071 | <<locked>> | 90% | 32,938 psi | 51% | 2395 fps | 95.4% |
| Norma 201 | <<locked>> | 80% | 53,606 psi | 82% | 2707 fps | 100% |
| Norma 202 | <<locked>> | 80% | 54,085 psi | 83% | 2700 fps | 100% |
| Norma 203B | <<locked>> | 80% | 49,559 psi | 76% | 2694 fps | 100% |
| Norma 204 | <<locked>> | 84% | 42,148 psi | 65% | 2598 fps | 95.3% |
| Norma MRP | <<locked>> | 88% | 37,956 psi | 58% | 2602 fps | 95.9% |
| Norma URP | <<locked>> | 80% | 37,507 psi | 58% | 2513 fps | 98.4% |
| Ramshot Big Game | <<locked>> | 80% | 50,024 psi | 77% | 2720 fps | 100% |
| Ramshot Grand | <<locked>> | 96% | 46,006 psi | 71% | 2746 fps | 95.5% |
| Ramshot Hunter | <<locked>> | 80% | 36,318 psi | 56% | 2497 fps | 96.4% |
| Ramshot Magnum | <<locked>> | 94% | 38,058 psi | 59% | 2562 fps | 95% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 27,862 psi | 43% | 1575 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 47,834 psi | 74% | 2651 fps | 98.8% |
| ReloadSwiss RS 52 | <<locked>> | 80% | 54,433 psi | 84% | 2825 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 44,237 psi | 68% | 2700 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 37,376 psi | 58% | 2533 fps | 98.2% |
| ReloadSwiss RS 70 | 51.4 gr | 80% | 36,390 psi | 56% | 2543 fps | 97.6% |
| ReloadSwiss RS 76 | <<locked>> | 96% | 37,884 psi | 58% | 2631 fps | 95.7% |
| Rottweil R 902 | <<locked>> | 80% | 51,039 psi | 79% | 2661 fps | 100% |
| Rottweil R 903 | <<locked>> | 80% | 44,686 psi | 69% | 2602 fps | 100% |
| Rottweil R 904 | <<locked>> | 90% | 46,079 psi | 71% | 2644 fps | 95.3% |
| Rottweil R 905 | <<locked>> | 88% | 40,277 psi | 62% | 2582 fps | 95.2% |
| Rottweil R 907 | <<locked>> | 80% | 41,655 psi | 64% | 2530 fps | 96.5% |
| Shooters World Long Rifle | <<locked>> | 80% | 40,727 psi | 63% | 2513 fps | 98.1% |
| Shooters World Precision | <<locked>> | 80% | 49,182 psi | 76% | 2648 fps | 100% |
| Shooters World SW4350 | <<locked>> | 80% | 38,899 psi | 60% | 2493 fps | 96.5% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 45,774 psi | 70% | 2654 fps | 100% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 53,171 psi | 82% | 2733 fps | 100% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 54,244 psi | 83% | 2635 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 45,890 psi | 71% | 2510 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 39,682 psi | 61% | 2457 fps | 96.6% |
| SNPE Vectan Tubal 8000 | <<locked>> | 88% | 39,900 psi | 61% | 2575 fps | 95% |
| Somchem S335 | <<locked>> | 80% | 54,085 psi | 83% | 2635 fps | 100% |
| Somchem S355 | <<locked>> | 80% | 45,020 psi | 69% | 2602 fps | 100% |
| Somchem S361 | <<locked>> | 92% | 50,473 psi | 78% | 2690 fps | 95.5% |
| Somchem S365 | <<locked>> | 80% | 34,040 psi | 52% | 2470 fps | 99.8% |
| Somchem S385 | <<locked>> | 86% | 38,435 psi | 59% | 2513 fps | 95.5% |
| Vihtavuori N133 | <<locked>> | 80% | 54,795 psi | 84% | 2618 fps | 100% |
| Vihtavuori N135 | <<locked>> | 80% | 51,314 psi | 79% | 2621 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 51,445 psi | 79% | 2635 fps | 100% |
| Vihtavuori N150 | <<locked>> | 80% | 42,917 psi | 66% | 2533 fps | 100% |
| Vihtavuori N160 | <<locked>> | 80% | 38,841 psi | 60% | 2510 fps | 98.6% |
| Vihtavuori N165 | <<locked>> | 92% | 40,451 psi | 62% | 2549 fps | 95.7% |
| Vihtavuori N540 | <<locked>> | 80% | 49,763 psi | 77% | 2631 fps | 100% |
| Vihtavuori N550 | <<locked>> | 80% | 38,392 psi | 59% | 2513 fps | 98.4% |
| Vihtavuori N555 | <<locked>> | 80% | 29,747 psi | 46% | 2365 fps | 96.6% |
| Vihtavuori N560 | <<locked>> | 94% | 47,152 psi | 73% | 2772 fps | 95.1% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 37,985 psi | 58% | 2484 fps | 99.8% |
| Winchester 760 | <<locked>> | 80% | 39,668 psi | 61% | 2562 fps | 96.6% |
| Winchester StaBALL HD | <<locked>> | 82% | 25,338 psi | 39% | 2316 fps | 96.2% |
| Winchester StaBALL Match | <<locked>> | 80% | 53,142 psi | 82% | 2736 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 92% | 43,178 psi | 66% | 2608 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 100 powders for .280 Ackley Improved loaded with the .284 | 158gr | Prvi Partizan Grom. Norma MRP delivers the highest muzzle velocity at 2,966 fps; across all powders the maximum-charge window runs from 1,719 fps to 2,966 fps. Accurate 3100 gives the best case fill at 100 %, and 100 of the 100 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 158.0 gr projectile in 0.284" calls for a 1:11.0 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, Hodgdon Superformance rank at the top here: for .280 Ackley Improved with the .284 | 158gr | Prvi Partizan Grom 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.