Load Specifications
Bullet:.284 | 155gr | Geco EXPRESS
Bullet Manufacturer:Geco
Bullet Weight:155 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 | 155gr | Geco EXPRESS bullet and 106 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are ReloadSwiss RS 70, Alliant Reloder-26 and Alliant Reloder-16.
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>> | 84% | 58,668 psi | 90% | 2746 fps | 100% |
| Accurate 2700 | <<locked>> | 84% | 56,130 psi | 86% | 2769 fps | 98.9% |
| Accurate 3100ᴾ | <<locked>> | 100% | 53,606 psi | 82% | 2808 fps | 99.6% |
| Accurate 4064 | <<locked>> | 86% | 58,697 psi | 90% | 2795 fps | 100% |
| Accurate 4350 | <<locked>> | 92% | 56,014 psi | 86% | 2861 fps | 100% |
| Accurate MAGPROᴾ | <<locked>> | 100% | 55,622 psi | 86% | 2946 fps | 96.3% |
| ADI AR 2206H | <<locked>> | 82% | 57,798 psi | 89% | 2831 fps | 100% |
| ADI AR 2208 | <<locked>> | 88% | 58,740 psi | 90% | 2831 fps | 100% |
| ADI AR 2209 | <<locked>> | 98% | 56,898 psi | 88% | 2904 fps | 98.5% |
| ADI AR 2213ᴾ | <<locked>> | 100% | 54,520 psi | 84% | 2894 fps | 96.9% |
| Alliant Power Pro 2000-MR | <<locked>> | 84% | 58,595 psi | 90% | 2963 fps | 100% |
| Alliant Power Pro Varmint | <<locked>> | 98% | 56,884 psi | 88% | 2900 fps | 98.5% |
| Alliant Power Pro Varmint | <<locked>> | 98% | 56,884 psi | 88% | 2900 fps | 98.5% |
| Alliant Reloder- TS 15.5 | <<locked>> | 86% | 56,057 psi | 86% | 2805 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 84% | 56,449 psi | 87% | 2831 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 94% | 56,550 psi | 87% | 2913 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 90% | 58,305 psi | 90% | 2940 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 98% | 56,072 psi | 86% | 2890 fps | 98.4% |
| Alliant Reloder-22ᴾ | <<locked>> | 100% | 53,374 psi | 82% | 2890 fps | 98.2% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 50,299 psi | 77% | 2825 fps | 100% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 43,874 psi | 67% | 2753 fps | 99.1% |
| Alliant Reloder-26ᴾ | <<locked>> | 100% | 58,291 psi | 90% | 3025 fps | 100% |
| Baschieri & Pellagri 107 | <<locked>> | 82% | 57,609 psi | 89% | 2848 fps | 100% |
| Bofors RP15ᴾ | <<locked>> | 100% | 48,965 psi | 75% | 2818 fps | 97.2% |
| Bofors RP3 | <<locked>> | 86% | 56,913 psi | 88% | 2822 fps | 100% |
| Bofors RP5ᴾ | <<locked>> | 100% | 53,374 psi | 82% | 2890 fps | 98.2% |
| Bofors RP7 | <<locked>> | 90% | 56,391 psi | 87% | 2812 fps | 99.1% |
| Hodgdon H380 | <<locked>> | 86% | 57,406 psi | 88% | 2841 fps | 100% |
| Hodgdon H414 | <<locked>> | 92% | 58,320 psi | 90% | 2917 fps | 99.6% |
| Hodgdon H4350 | <<locked>> | 90% | 57,943 psi | 89% | 2871 fps | 98.8% |
| Hodgdon H4831ᴾ | <<locked>> | 100% | 58,552 psi | 90% | 2900 fps | 97.1% |
| Hodgdon H4831 SCᴾ | <<locked>> | 100% | 57,276 psi | 88% | 2881 fps | 96.8% |
| Hodgdon H4895 | <<locked>> | 82% | 58,436 psi | 90% | 2838 fps | 100% |
| Hodgdon Hybrid 100V | <<locked>> | 96% | 56,869 psi | 87% | 2835 fps | 100% |
| Hodgdon LEVERevolution | <<locked>> | 84% | 58,682 psi | 90% | 2874 fps | 100% |
| Hodgdon Retumboᴾ | <<locked>> | 100% | 43,047 psi | 66% | 2779 fps | 96.3% |
| Hodgdon Superformance | <<locked>> | 92% | 58,581 psi | 90% | 2953 fps | 99.5% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 36,506 psi | 56% | 1739 fps | 100% |
| Hodgdon VARGET | <<locked>> | 82% | 55,767 psi | 86% | 2789 fps | 100% |
| IMR 4064 | <<locked>> | 86% | 58,436 psi | 90% | 2818 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 84% | 57,537 psi | 89% | 2805 fps | 99.5% |
| IMR 4350 | <<locked>> | 94% | 57,246 psi | 88% | 2841 fps | 99.2% |
| IMR 4451 Enduron | <<locked>> | 90% | 57,841 psi | 89% | 2835 fps | 99.5% |
| IMR 4831 | <<locked>> | 94% | 56,231 psi | 87% | 2848 fps | 100% |
| IMR 4895 | <<locked>> | 84% | 57,957 psi | 89% | 2858 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 98% | 56,318 psi | 87% | 2831 fps | 96.8% |
| IMR 7828 SSCᴾ | <<locked>> | 100% | 51,967 psi | 80% | 2867 fps | 96.5% |
| Lovex D073.6 | <<locked>> | 82% | 58,378 psi | 90% | 2802 fps | 100% |
| Lovex S060 | <<locked>> | 82% | 56,289 psi | 87% | 2749 fps | 100% |
| Lovex S062 | <<locked>> | 86% | 58,610 psi | 90% | 2808 fps | 100% |
| Lovex S065 | <<locked>> | 92% | 58,059 psi | 89% | 2831 fps | 99.9% |
| Lovex S070 | <<locked>> | 92% | 55,912 psi | 86% | 2825 fps | 99.5% |
| Lovex S071ᴾ | <<locked>> | 100% | 44,788 psi | 69% | 2664 fps | 98.5% |
| Norma 201 | <<locked>> | 82% | 56,420 psi | 87% | 2772 fps | 100% |
| Norma 202 | <<locked>> | 82% | 57,232 psi | 88% | 2769 fps | 100% |
| Norma 203B | <<locked>> | 84% | 55,738 psi | 86% | 2818 fps | 100% |
| Norma 204 | <<locked>> | 94% | 58,392 psi | 90% | 2900 fps | 98.5% |
| Norma MRPᴾ | <<locked>> | 100% | 56,840 psi | 87% | 2979 fps | 99.5% |
| Norma URP | <<locked>> | 94% | 58,291 psi | 90% | 2897 fps | 100% |
| Ramshot Big Game | <<locked>> | 84% | 56,507 psi | 87% | 2841 fps | 100% |
| Ramshot Grandᴾ | <<locked>> | 100% | 52,069 psi | 80% | 2881 fps | 96.9% |
| Ramshot Hunter | <<locked>> | 94% | 57,130 psi | 88% | 2900 fps | 99.8% |
| Ramshot Magnumᴾ | <<locked>> | 100% | 46,586 psi | 72% | 2756 fps | 97.4% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 37,188 psi | 57% | 1781 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 86% | 57,435 psi | 88% | 2828 fps | 99.7% |
| ReloadSwiss RS 52 | <<locked>> | 82% | 57,580 psi | 89% | 2900 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 88% | 57,696 psi | 89% | 2930 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 92% | 55,898 psi | 86% | 2884 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 94% | 58,160 psi | 89% | 2969 fps | 100% |
| ReloadSwiss RS 76ᴾ | <<locked>> | 100% | 42,728 psi | 66% | 2769 fps | 97.3% |
| Rottweil R 902 | <<locked>> | 84% | 56,884 psi | 88% | 2769 fps | 100% |
| Rottweil R 903 | <<locked>> | 88% | 57,072 psi | 88% | 2818 fps | 100% |
| Rottweil R 904 | <<locked>> | 98% | 58,682 psi | 90% | 2874 fps | 97.8% |
| Rottweil R 905 | <<locked>> | 98% | 55,492 psi | 85% | 2877 fps | 98.5% |
| Rottweil R 907 | <<locked>> | 90% | 56,391 psi | 87% | 2812 fps | 99.1% |
| Shooters World Long Rifle | <<locked>> | 92% | 58,059 psi | 89% | 2831 fps | 99.9% |
| Shooters World Match Rifle | <<locked>> | 82% | 58,378 psi | 90% | 2802 fps | 100% |
| Shooters World Precision | <<locked>> | 86% | 58,610 psi | 90% | 2808 fps | 100% |
| Shooters World SW4350 | <<locked>> | 92% | 55,912 psi | 86% | 2825 fps | 99.5% |
| SNPE Vectan SP 11 | <<locked>> | 88% | 58,653 psi | 90% | 2877 fps | 100% |
| SNPE Vectan SP 9 | <<locked>> | 82% | 56,159 psi | 86% | 2802 fps | 100% |
| SNPE Vectan Tubal 3000 | <<locked>> | 82% | 57,217 psi | 88% | 2700 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 88% | 58,044 psi | 89% | 2703 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 92% | 57,783 psi | 89% | 2789 fps | 99.5% |
| SNPE Vectan Tubal 8000ᴾ | <<locked>> | 100% | 58,740 psi | 90% | 2930 fps | 98.9% |
| Somchem S335 | <<locked>> | 82% | 56,855 psi | 87% | 2697 fps | 100% |
| Somchem S341 | <<locked>> | 82% | 58,639 psi | 90% | 2818 fps | 100% |
| Somchem S355 | <<locked>> | 88% | 56,913 psi | 88% | 2812 fps | 100% |
| Somchem S361 | <<locked>> | 96% | 56,797 psi | 87% | 2812 fps | 96.7% |
| Somchem S365 | <<locked>> | 96% | 57,580 psi | 89% | 2897 fps | 100% |
| Somchem S385 | <<locked>> | 98% | 56,159 psi | 86% | 2854 fps | 99.1% |
| Vihtavuori N133 | <<locked>> | 82% | 57,754 psi | 89% | 2684 fps | 100% |
| Vihtavuori N135 | <<locked>> | 84% | 57,377 psi | 88% | 2730 fps | 100% |
| Vihtavuori N140 | <<locked>> | 84% | 57,609 psi | 89% | 2746 fps | 100% |
| Vihtavuori N150 | <<locked>> | 90% | 58,363 psi | 90% | 2789 fps | 100% |
| Vihtavuori N160 | <<locked>> | 92% | 56,782 psi | 87% | 2838 fps | 100% |
| Vihtavuori N165ᴾ | <<locked>> | 100% | 51,648 psi | 79% | 2772 fps | 98.1% |
| Vihtavuori N540 | <<locked>> | 84% | 55,883 psi | 86% | 2743 fps | 100% |
| Vihtavuori N550 | <<locked>> | 92% | 55,840 psi | 86% | 2844 fps | 100% |
| Vihtavuori N555ᴾ | <<locked>> | 100% | 56,623 psi | 87% | 2907 fps | 100% |
| Vihtavuori N560ᴾ | <<locked>> | 100% | 57,203 psi | 88% | 2969 fps | 97.2% |
| Winchester 6.5 StaBALL | <<locked>> | 92% | 56,333 psi | 87% | 2805 fps | 100% |
| Winchester 760 | <<locked>> | 92% | 58,320 psi | 90% | 2917 fps | 99.6% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 45,484 psi | 70% | 2884 fps | 100% |
| Winchester StaBALL Match | <<locked>> | 82% | 56,391 psi | 87% | 2812 fps | 100% |
| Winchester Supreme 780ᴾ | <<locked>> | 100% | 56,275 psi | 87% | 2848 fps | 98.3% |
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 2495 | <<locked>> | 80% | 51,503 psi | 79% | 2651 fps | 100% |
| Accurate 2700 | <<locked>> | 80% | 49,342 psi | 76% | 2661 fps | 97.9% |
| Accurate 3100 | <<locked>> | 86% | 33,446 psi | 51% | 2431 fps | 95.3% |
| Accurate 4064 | <<locked>> | 80% | 48,820 psi | 75% | 2661 fps | 100% |
| Accurate 4350 | <<locked>> | 80% | 37,260 psi | 57% | 2530 fps | 98.2% |
| Accurate MAGPRO | <<locked>> | 98% | 52,054 psi | 80% | 2887 fps | 95.4% |
| ADI AR 2206H | <<locked>> | 80% | 54,288 psi | 84% | 2779 fps | 100% |
| ADI AR 2208 | <<locked>> | 80% | 45,948 psi | 71% | 2631 fps | 99.8% |
| ADI AR 2209 | <<locked>> | 90% | 43,888 psi | 68% | 2677 fps | 95.7% |
| ADI AR 2213 | <<locked>> | 96% | 47,834 psi | 74% | 2776 fps | 95.2% |
| Alliant Power Pro 2000-MR | <<locked>> | 80% | 50,792 psi | 78% | 2844 fps | 100% |
| Alliant Power Pro Varmint | <<locked>> | 88% | 41,249 psi | 63% | 2621 fps | 95% |
| Alliant Power Pro Varmint | <<locked>> | 88% | 41,249 psi | 63% | 2621 fps | 95% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 46,615 psi | 72% | 2661 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 80% | 49,806 psi | 77% | 2726 fps | 100% |
| Alliant Reloder-16 | 47.1 gr | 80% | 36,274 psi | 56% | 2539 fps | 98.3% |
| Alliant Reloder-17 | <<locked>> | 80% | 40,973 psi | 63% | 2661 fps | 99.9% |
| Alliant Reloder-19 | <<locked>> | 90% | 43,468 psi | 67% | 2667 fps | 95.7% |
| Alliant Reloder-22 | <<locked>> | 92% | 40,915 psi | 63% | 2661 fps | 95.1% |
| Alliant Reloder-23 | <<locked>> | 80% | 26,585 psi | 41% | 2297 fps | 95.9% |
| Alliant Reloder-25 | <<locked>> | 90% | 32,039 psi | 49% | 2467 fps | 95% |
| Alliant Reloder-26 | 53.3 gr | 82% | 30,327 psi | 47% | 2461 fps | 95.2% |
| Baschieri & Pellagri 107 | <<locked>> | 80% | 53,911 psi | 83% | 2795 fps | 100% |
| Bofors RP15 | <<locked>> | 96% | 43,018 psi | 66% | 2703 fps | 95.6% |
| Bofors RP3 | <<locked>> | 80% | 46,891 psi | 72% | 2671 fps | 100% |
| Bofors RP5 | <<locked>> | 92% | 40,915 psi | 63% | 2661 fps | 95.1% |
| Bofors RP7 | <<locked>> | 80% | 41,321 psi | 64% | 2546 fps | 96.2% |
| Hodgdon H380 | <<locked>> | 80% | 47,210 psi | 73% | 2680 fps | 99.5% |
| Hodgdon H414 | <<locked>> | 80% | 39,044 psi | 60% | 2572 fps | 96.2% |
| Hodgdon H4350 | <<locked>> | 80% | 42,090 psi | 65% | 2595 fps | 95.6% |
| Hodgdon H4831 | <<locked>> | 96% | 51,039 psi | 79% | 2782 fps | 95.5% |
| Hodgdon H4831 SC | <<locked>> | 96% | 50,212 psi | 77% | 2769 fps | 95.3% |
| Hodgdon H4895 | <<locked>> | 80% | 54,926 psi | 85% | 2789 fps | 100% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 33,823 psi | 52% | 2434 fps | 98.8% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 51,416 psi | 79% | 2769 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 98% | 40,408 psi | 62% | 2717 fps | 95.2% |
| Hodgdon Superformance | <<locked>> | 80% | 37,985 psi | 58% | 2579 fps | 95.3% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,224 psi | 42% | 1552 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 52,344 psi | 81% | 2736 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 48,312 psi | 74% | 2667 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 80% | 50,589 psi | 78% | 2697 fps | 98.7% |
| IMR 4350 | <<locked>> | 82% | 39,349 psi | 61% | 2526 fps | 95.6% |
| IMR 4451 Enduron | <<locked>> | 80% | 42,699 psi | 66% | 2575 fps | 97% |
| IMR 4831 | <<locked>> | 80% | 35,679 psi | 55% | 2480 fps | 97.9% |
| IMR 4895 | <<locked>> | 80% | 51,053 psi | 79% | 2756 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 94% | 49,705 psi | 76% | 2723 fps | 95.4% |
| IMR 7828 SSC | <<locked>> | 98% | 48,646 psi | 75% | 2805 fps | 95.6% |
| Lovex D073.6 | <<locked>> | 80% | 54,476 psi | 84% | 2749 fps | 100% |
| Lovex S060 | <<locked>> | 80% | 52,910 psi | 81% | 2700 fps | 100% |
| Lovex S062 | <<locked>> | 80% | 48,559 psi | 75% | 2664 fps | 100% |
| Lovex S065 | <<locked>> | 80% | 40,219 psi | 62% | 2526 fps | 97.8% |
| Lovex S070 | <<locked>> | 80% | 38,363 psi | 59% | 2507 fps | 96.2% |
| Lovex S071 | <<locked>> | 92% | 34,621 psi | 53% | 2457 fps | 95.8% |
| Norma 201 | <<locked>> | 80% | 52,953 psi | 81% | 2723 fps | 100% |
| Norma 202 | <<locked>> | 80% | 53,722 psi | 83% | 2720 fps | 100% |
| Norma 203B | <<locked>> | 80% | 49,182 psi | 76% | 2713 fps | 100% |
| Norma 204 | <<locked>> | 86% | 44,541 psi | 69% | 2667 fps | 95.8% |
| Norma MRP | <<locked>> | 88% | 37,492 psi | 58% | 2615 fps | 95.4% |
| Norma URP | <<locked>> | 80% | 36,927 psi | 57% | 2523 fps | 98% |
| Ramshot Big Game | <<locked>> | 80% | 49,313 psi | 76% | 2733 fps | 100% |
| Ramshot Grand | <<locked>> | 96% | 45,208 psi | 70% | 2753 fps | 95% |
| Ramshot Hunter | <<locked>> | 80% | 35,752 psi | 55% | 2507 fps | 96% |
| Ramshot Magnum | <<locked>> | 96% | 40,176 psi | 62% | 2631 fps | 95.5% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 27,702 psi | 43% | 1588 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 47,210 psi | 73% | 2664 fps | 98.6% |
| ReloadSwiss RS 52 | <<locked>> | 80% | 53,635 psi | 83% | 2841 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 43,569 psi | 67% | 2713 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 36,912 psi | 57% | 2546 fps | 97.9% |
| ReloadSwiss RS 70 | 51.5 gr | 80% | 35,839 psi | 55% | 2549 fps | 97.2% |
| ReloadSwiss RS 76 | <<locked>> | 96% | 37,202 psi | 57% | 2635 fps | 95% |
| Rottweil R 902 | <<locked>> | 80% | 50,430 psi | 78% | 2677 fps | 100% |
| Rottweil R 903 | <<locked>> | 80% | 44,063 psi | 68% | 2615 fps | 100% |
| Rottweil R 904 | <<locked>> | 92% | 48,428 psi | 75% | 2707 fps | 95.7% |
| Rottweil R 905 | <<locked>> | 90% | 42,583 psi | 66% | 2654 fps | 95.7% |
| Rottweil R 907 | <<locked>> | 80% | 41,321 psi | 64% | 2546 fps | 96.2% |
| Shooters World Long Rifle | <<locked>> | 80% | 40,219 psi | 62% | 2526 fps | 97.8% |
| Shooters World Match Rifle | <<locked>> | 80% | 54,476 psi | 84% | 2749 fps | 100% |
| Shooters World Precision | <<locked>> | 80% | 48,559 psi | 75% | 2664 fps | 100% |
| Shooters World SW4350 | <<locked>> | 80% | 38,363 psi | 59% | 2507 fps | 96.2% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 45,136 psi | 69% | 2667 fps | 99.9% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 52,518 psi | 81% | 2749 fps | 100% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 53,650 psi | 83% | 2654 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 45,368 psi | 70% | 2526 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 39,407 psi | 61% | 2474 fps | 96.3% |
| SNPE Vectan Tubal 8000 | <<locked>> | 90% | 42,177 psi | 65% | 2648 fps | 95.5% |
| Somchem S335 | <<locked>> | 80% | 53,490 psi | 82% | 2654 fps | 100% |
| Somchem S341 | <<locked>> | 80% | 54,795 psi | 84% | 2769 fps | 100% |
| Somchem S355 | <<locked>> | 80% | 44,425 psi | 68% | 2618 fps | 100% |
| Somchem S361 | <<locked>> | 92% | 49,676 psi | 76% | 2700 fps | 95.1% |
| Somchem S365 | <<locked>> | 80% | 33,475 psi | 51% | 2480 fps | 99.6% |
| Somchem S385 | <<locked>> | 86% | 37,840 psi | 58% | 2523 fps | 95% |
| Vihtavuori N133 | <<locked>> | 80% | 54,215 psi | 83% | 2638 fps | 100% |
| Vihtavuori N135 | <<locked>> | 80% | 50,633 psi | 78% | 2638 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 50,821 psi | 78% | 2651 fps | 100% |
| Vihtavuori N150 | <<locked>> | 80% | 42,351 psi | 65% | 2546 fps | 100% |
| Vihtavuori N160 | <<locked>> | 80% | 38,493 psi | 59% | 2526 fps | 98.4% |
| Vihtavuori N165 | <<locked>> | 92% | 39,740 psi | 61% | 2556 fps | 95.2% |
| Vihtavuori N540 | <<locked>> | 80% | 49,139 psi | 76% | 2648 fps | 100% |
| Vihtavuori N550 | <<locked>> | 80% | 37,826 psi | 58% | 2523 fps | 98% |
| Vihtavuori N555 | <<locked>> | 80% | 29,196 psi | 45% | 2372 fps | 96.1% |
| Vihtavuori N560 | <<locked>> | 96% | 49,647 psi | 76% | 2841 fps | 95.5% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 37,449 psi | 58% | 2493 fps | 99.6% |
| Winchester 760 | <<locked>> | 80% | 39,276 psi | 60% | 2579 fps | 96.3% |
| Winchester StaBALL HD | <<locked>> | 82% | 25,077 psi | 39% | 2323 fps | 95.6% |
| Winchester StaBALL Match | <<locked>> | 80% | 52,721 psi | 81% | 2756 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 92% | 42,685 psi | 66% | 2621 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 106 powders for .280 Ackley Improved loaded with the .284 | 155gr | Geco EXPRESS. Alliant Reloder-26 delivers the highest muzzle velocity at 3,025 fps; across all powders the maximum-charge window runs from 1,739 fps to 3,025 fps. Accurate 3100 gives the best case fill at 100 %, and 106 of the 106 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 155.0 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. ReloadSwiss RS 70, Alliant Reloder-26, Alliant Reloder-16 rank at the top here: for .280 Ackley Improved with the .284 | 155gr | Geco EXPRESS 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.