Load Specifications
Load data in caliber .280 Ackley Improved with .284 | 123gr | RWS Kegelspitz bullet and 97 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are ReloadSwiss RS 70, Hodgdon Superformance and Alliant Reloder-17.
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 2015 | <<locked>> | 82% | 56,449 psi | 87% | 3025 fps | 100% |
| Accurate 2495 | <<locked>> | 86% | 56,115 psi | 86% | 3054 fps | 100% |
| Accurate 2520 | <<locked>> | 82% | 57,493 psi | 88% | 3123 fps | 100% |
| Accurate 2700 | <<locked>> | 88% | 58,001 psi | 89% | 3107 fps | 97.5% |
| Accurate 3100ᴾ | <<locked>> | 100% | 47,007 psi | 72% | 2999 fps | 97.1% |
| Accurate 4064 | <<locked>> | 88% | 56,057 psi | 86% | 3104 fps | 100% |
| Accurate 4350 | <<locked>> | 96% | 56,594 psi | 87% | 3196 fps | 99.7% |
| ADI AR 2206H | <<locked>> | 84% | 55,796 psi | 86% | 3133 fps | 99.9% |
| ADI AR 2208 | <<locked>> | 90% | 57,000 psi | 88% | 3136 fps | 99.9% |
| ADI AR 2209ᴾ | <<locked>> | 100% | 54,520 psi | 84% | 3169 fps | 95.9% |
| ADI Benchmark 8208 | <<locked>> | 84% | 58,117 psi | 89% | 3136 fps | 100% |
| Alliant AR-Comp | <<locked>> | 82% | 55,985 psi | 86% | 3058 fps | 100% |
| Alliant Power Pro 2000-MR | <<locked>> | 86% | 55,883 psi | 86% | 3264 fps | 99.9% |
| Alliant Reloder- TS 15.5 | <<locked>> | 90% | 57,319 psi | 88% | 3159 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 88% | 57,870 psi | 89% | 3186 fps | 99.9% |
| Alliant Reloder-16 | <<locked>> | 98% | 57,406 psi | 88% | 3261 fps | 99.9% |
| Alliant Reloder-17 | <<locked>> | 92% | 55,245 psi | 85% | 3235 fps | 100% |
| Alliant Reloder-19ᴾ | <<locked>> | 100% | 53,359 psi | 82% | 3153 fps | 95.8% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 44,251 psi | 68% | 3025 fps | 99.5% |
| Alliant Reloder-26ᴾ | <<locked>> | 100% | 50,575 psi | 78% | 3222 fps | 99.2% |
| Baschieri & Pellagri 107 | <<locked>> | 84% | 55,680 psi | 86% | 3146 fps | 99.7% |
| Bofors RP3 | <<locked>> | 90% | 58,334 psi | 90% | 3179 fps | 100% |
| Bofors RP7 | <<locked>> | 94% | 57,798 psi | 89% | 3146 fps | 97.7% |
| Hodgdon Benchmark | <<locked>> | 82% | 55,999 psi | 86% | 3064 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 84% | 58,030 psi | 89% | 3166 fps | 100% |
| Hodgdon H380 | <<locked>> | 88% | 55,259 psi | 85% | 3133 fps | 99.3% |
| Hodgdon H414 | <<locked>> | 94% | 55,419 psi | 85% | 3189 fps | 97.9% |
| Hodgdon H4350 | <<locked>> | 92% | 55,651 psi | 86% | 3150 fps | 96.7% |
| Hodgdon H4895 | <<locked>> | 84% | 56,405 psi | 87% | 3146 fps | 100% |
| Hodgdon Hybrid 100Vᴾ | <<locked>> | 100% | 57,508 psi | 88% | 3176 fps | 100% |
| Hodgdon LEVERevolution | <<locked>> | 86% | 56,478 psi | 87% | 3182 fps | 100% |
| Hodgdon Superformance | <<locked>> | 94% | 55,898 psi | 86% | 3225 fps | 97.7% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 35,911 psi | 55% | 1965 fps | 100% |
| Hodgdon VARGET | <<locked>> | 86% | 57,522 psi | 88% | 3146 fps | 100% |
| IMR 3031 | <<locked>> | 84% | 56,811 psi | 87% | 3130 fps | 100% |
| IMR 4064 | <<locked>> | 88% | 56,347 psi | 87% | 3120 fps | 99.9% |
| IMR 4166 Enduron | <<locked>> | 86% | 55,883 psi | 86% | 3091 fps | 97.9% |
| IMR 4350 | <<locked>> | 98% | 58,566 psi | 90% | 3176 fps | 97.9% |
| IMR 4451 Enduron | <<locked>> | 92% | 55,985 psi | 86% | 3120 fps | 97.8% |
| IMR 4831 | <<locked>> | 98% | 57,000 psi | 88% | 3186 fps | 99.7% |
| IMR 4895 | <<locked>> | 86% | 55,666 psi | 86% | 3159 fps | 100% |
| IMR 8208 XBR | <<locked>> | 84% | 58,117 psi | 89% | 3136 fps | 100% |
| Lovex D073.6 | <<locked>> | 84% | 55,854 psi | 86% | 3107 fps | 100% |
| Lovex S060 | <<locked>> | 86% | 58,392 psi | 90% | 3114 fps | 100% |
| Lovex S062 | <<locked>> | 88% | 56,289 psi | 87% | 3114 fps | 100% |
| Lovex S065 | <<locked>> | 94% | 55,782 psi | 86% | 3117 fps | 98.9% |
| Lovex S070 | <<locked>> | 96% | 57,145 psi | 88% | 3156 fps | 98.3% |
| Norma 201 | <<locked>> | 86% | 58,073 psi | 89% | 3133 fps | 100% |
| Norma 202 | <<locked>> | 86% | 58,726 psi | 90% | 3133 fps | 100% |
| Norma 203B | <<locked>> | 88% | 57,087 psi | 88% | 3173 fps | 100% |
| Norma 204 | <<locked>> | 96% | 55,898 psi | 86% | 3169 fps | 96.1% |
| Norma MRPᴾ | <<locked>> | 100% | 49,763 psi | 77% | 3166 fps | 96.7% |
| Norma URP | <<locked>> | 96% | 55,506 psi | 85% | 3182 fps | 99.6% |
| Ramshot Big Game | <<locked>> | 88% | 58,015 psi | 89% | 3196 fps | 100% |
| Ramshot Hunter | <<locked>> | 98% | 58,001 psi | 89% | 3238 fps | 99% |
| Ramshot TAC | <<locked>> | 84% | 58,407 psi | 90% | 3156 fps | 99.3% |
| Ramshot Wild Boar | <<locked>> | 84% | 58,378 psi | 90% | 3176 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 36,419 psi | 56% | 2008 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 88% | 55,492 psi | 85% | 3117 fps | 98.3% |
| ReloadSwiss RS 52 | <<locked>> | 86% | 58,798 psi | 90% | 3261 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 92% | 58,784 psi | 90% | 3294 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 96% | 56,478 psi | 87% | 3219 fps | 99.6% |
| ReloadSwiss RS 70 | <<locked>> | 96% | 55,564 psi | 85% | 3248 fps | 99.4% |
| Rottweil R 901 | <<locked>> | 84% | 58,813 psi | 90% | 3110 fps | 100% |
| Rottweil R 902 | <<locked>> | 88% | 58,479 psi | 90% | 3130 fps | 100% |
| Rottweil R 903 | <<locked>> | 92% | 58,189 psi | 90% | 3173 fps | 100% |
| Rottweil R 907 | <<locked>> | 94% | 57,798 psi | 89% | 3146 fps | 97.7% |
| Shooters World Long Rifle | <<locked>> | 94% | 55,782 psi | 86% | 3117 fps | 98.9% |
| Shooters World Match Rifle | <<locked>> | 84% | 55,854 psi | 86% | 3107 fps | 100% |
| Shooters World Precision | <<locked>> | 88% | 56,289 psi | 87% | 3114 fps | 100% |
| Shooters World SW4350 | <<locked>> | 96% | 57,145 psi | 88% | 3156 fps | 98.3% |
| SNPE Vectan SP 11 | <<locked>> | 90% | 56,362 psi | 87% | 3179 fps | 100% |
| SNPE Vectan SP 7 | <<locked>> | 84% | 57,116 psi | 88% | 3133 fps | 99.4% |
| SNPE Vectan SP 9 | <<locked>> | 86% | 57,856 psi | 89% | 3159 fps | 100% |
| SNPE Vectan Tubal 3000 | <<locked>> | 84% | 55,492 psi | 85% | 3009 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 90% | 56,231 psi | 87% | 3009 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 94% | 56,072 psi | 86% | 3068 fps | 97.9% |
| Somchem S335 | <<locked>> | 86% | 58,697 psi | 90% | 3058 fps | 100% |
| Somchem S341 | <<locked>> | 84% | 56,739 psi | 87% | 3123 fps | 100% |
| Somchem S355 | <<locked>> | 92% | 58,320 psi | 90% | 3166 fps | 100% |
| Somchem S365ᴾ | <<locked>> | 100% | 57,885 psi | 89% | 3241 fps | 100% |
| Somchem S385ᴾ | <<locked>> | 100% | 53,156 psi | 82% | 3114 fps | 96.9% |
| Vihtavuori N130 | <<locked>> | 82% | 58,566 psi | 90% | 3018 fps | 100% |
| Vihtavuori N133 | <<locked>> | 84% | 55,869 psi | 86% | 2992 fps | 100% |
| Vihtavuori N135 | <<locked>> | 88% | 58,711 psi | 90% | 3091 fps | 100% |
| Vihtavuori N140 | <<locked>> | 86% | 55,796 psi | 86% | 3058 fps | 100% |
| Vihtavuori N150 | <<locked>> | 92% | 56,115 psi | 86% | 3087 fps | 100% |
| Vihtavuori N160 | <<locked>> | 96% | 57,711 psi | 89% | 3176 fps | 99.7% |
| Vihtavuori N530 | <<locked>> | 84% | 58,769 psi | 90% | 3136 fps | 100% |
| Vihtavuori N540 | <<locked>> | 88% | 57,493 psi | 88% | 3100 fps | 100% |
| Vihtavuori N550 | <<locked>> | 96% | 56,927 psi | 88% | 3182 fps | 99.6% |
| Vihtavuori N555ᴾ | <<locked>> | 100% | 49,501 psi | 76% | 3117 fps | 99.4% |
| Winchester 6.5 StaBALL | <<locked>> | 96% | 58,175 psi | 89% | 3153 fps | 100% |
| Winchester 748 | <<locked>> | 82% | 55,448 psi | 85% | 3133 fps | 100% |
| Winchester 760 | <<locked>> | 94% | 55,651 psi | 86% | 3192 fps | 97.9% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 39,842 psi | 61% | 3045 fps | 99.6% |
| Winchester StaBALL Match | <<locked>> | 86% | 58,059 psi | 89% | 3169 fps | 100% |
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 2015 | <<locked>> | 80% | 53,171 psi | 82% | 2976 fps | 100% |
| Accurate 2495 | <<locked>> | 80% | 46,093 psi | 71% | 2897 fps | 100% |
| Accurate 2520 | <<locked>> | 80% | 53,563 psi | 82% | 3064 fps | 100% |
| Accurate 2700 | <<locked>> | 82% | 47,688 psi | 73% | 2927 fps | 95.3% |
| Accurate 3100 | <<locked>> | 96% | 40,857 psi | 63% | 2874 fps | 95.3% |
| Accurate 4064 | <<locked>> | 80% | 43,584 psi | 67% | 2894 fps | 100% |
| Accurate 4350 | <<locked>> | 82% | 34,809 psi | 54% | 2756 fps | 95.1% |
| ADI AR 2206H | <<locked>> | 80% | 49,081 psi | 76% | 3018 fps | 99.5% |
| ADI AR 2208 | <<locked>> | 80% | 41,713 psi | 64% | 2851 fps | 97.9% |
| ADI AR 2209 | <<locked>> | 98% | 50,995 psi | 78% | 3104 fps | 95% |
| ADI Benchmark 8208 | <<locked>> | 80% | 51,184 psi | 79% | 3025 fps | 100% |
| Alliant AR-Comp | <<locked>> | 80% | 52,286 psi | 80% | 3005 fps | 100% |
| Alliant Power Pro 2000-MR | <<locked>> | 80% | 45,324 psi | 70% | 3061 fps | 98.7% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 41,843 psi | 64% | 2877 fps | 99.1% |
| Alliant Reloder-15 | <<locked>> | 80% | 44,715 psi | 69% | 2946 fps | 98.6% |
| Alliant Reloder-16 | <<locked>> | 82% | 34,505 psi | 53% | 2769 fps | 95.1% |
| Alliant Reloder-17 | 54.2 gr | 80% | 36,274 psi | 56% | 2841 fps | 97.7% |
| Alliant Reloder-19 | <<locked>> | 98% | 50,038 psi | 77% | 3091 fps | 95% |
| Alliant Reloder-23 | <<locked>> | 90% | 32,227 psi | 50% | 2726 fps | 96% |
| Alliant Reloder-26 | <<locked>> | 92% | 37,666 psi | 58% | 2930 fps | 95.6% |
| Baschieri & Pellagri 107 | <<locked>> | 80% | 48,617 psi | 75% | 3022 fps | 98.9% |
| Bofors RP3 | <<locked>> | 80% | 41,829 psi | 64% | 2884 fps | 99.2% |
| Bofors RP7 | <<locked>> | 88% | 47,921 psi | 74% | 2969 fps | 95.6% |
| Hodgdon Benchmark | <<locked>> | 80% | 52,576 psi | 81% | 3009 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 80% | 50,778 psi | 78% | 3051 fps | 100% |
| Hodgdon H380 | <<locked>> | 80% | 42,293 psi | 65% | 2884 fps | 97% |
| Hodgdon H414 | <<locked>> | 88% | 45,469 psi | 70% | 3002 fps | 95.6% |
| Hodgdon H4350 | <<locked>> | 88% | 48,950 psi | 75% | 3025 fps | 95% |
| Hodgdon H4895 | <<locked>> | 80% | 49,603 psi | 76% | 3031 fps | 99.8% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 29,820 psi | 46% | 2598 fps | 95% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 45,934 psi | 71% | 2999 fps | 99.7% |
| Hodgdon Superformance | 63.1 gr | 88% | 45,150 psi | 69% | 3018 fps | 95% |
| Hodgdon TrailBoss | <<locked>> | 80% | 26,687 psi | 41% | 1755 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 47,427 psi | 73% | 2972 fps | 99.6% |
| IMR 3031 | <<locked>> | 80% | 49,821 psi | 77% | 3022 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 43,845 psi | 67% | 2890 fps | 98.6% |
| IMR 4166 Enduron | <<locked>> | 80% | 46,209 psi | 71% | 2913 fps | 95.8% |
| IMR 4350 | <<locked>> | 92% | 48,385 psi | 74% | 2999 fps | 95.8% |
| IMR 4451 Enduron | <<locked>> | 86% | 46,601 psi | 72% | 2946 fps | 95.8% |
| IMR 4831 | <<locked>> | 84% | 35,911 psi | 55% | 2769 fps | 95.7% |
| IMR 4895 | <<locked>> | 80% | 45,832 psi | 71% | 2979 fps | 99.2% |
| IMR 8208 XBR | <<locked>> | 80% | 51,184 psi | 79% | 3025 fps | 100% |
| Lovex D073.6 | <<locked>> | 80% | 48,950 psi | 75% | 2995 fps | 100% |
| Lovex S060 | <<locked>> | 80% | 48,559 psi | 75% | 2943 fps | 99.5% |
| Lovex S062 | <<locked>> | 80% | 43,903 psi | 68% | 2894 fps | 99.6% |
| Lovex S065 | <<locked>> | 84% | 41,002 psi | 63% | 2828 fps | 95.8% |
| Lovex S070 | <<locked>> | 88% | 44,469 psi | 68% | 2923 fps | 95.6% |
| Norma 201 | <<locked>> | 80% | 48,095 psi | 74% | 2966 fps | 99.9% |
| Norma 202 | <<locked>> | 80% | 48,646 psi | 75% | 2969 fps | 100% |
| Norma 203B | <<locked>> | 80% | 44,063 psi | 68% | 2933 fps | 98.9% |
| Norma 204 | <<locked>> | 94% | 51,967 psi | 80% | 3100 fps | 95.2% |
| Norma MRP | <<locked>> | 98% | 46,528 psi | 72% | 3097 fps | 95.7% |
| Norma URP | <<locked>> | 82% | 34,853 psi | 54% | 2756 fps | 95% |
| Ramshot Big Game | <<locked>> | 80% | 44,106 psi | 68% | 2953 fps | 98.8% |
| Ramshot Hunter | <<locked>> | 88% | 41,452 psi | 64% | 2920 fps | 95.4% |
| Ramshot TAC | <<locked>> | 80% | 51,126 psi | 79% | 3031 fps | 98.3% |
| Ramshot Wild Boar | <<locked>> | 80% | 50,966 psi | 78% | 3054 fps | 99.7% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 27,209 psi | 42% | 1801 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 42,641 psi | 66% | 2867 fps | 95.4% |
| ReloadSwiss RS 52 | <<locked>> | 80% | 47,790 psi | 74% | 3068 fps | 99.1% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 38,580 psi | 59% | 2917 fps | 99.8% |
| ReloadSwiss RS 62 | <<locked>> | 84% | 37,086 psi | 57% | 2835 fps | 95.6% |
| ReloadSwiss RS 70 | 59.2 gr | 86% | 39,233 psi | 60% | 2907 fps | 95.7% |
| Rottweil R 901 | <<locked>> | 80% | 52,069 psi | 80% | 3005 fps | 100% |
| Rottweil R 902 | <<locked>> | 80% | 45,658 psi | 70% | 2910 fps | 99.7% |
| Rottweil R 903 | <<locked>> | 80% | 39,160 psi | 60% | 2818 fps | 98.5% |
| Rottweil R 907 | <<locked>> | 88% | 47,921 psi | 74% | 2969 fps | 95.6% |
| Shooters World Long Rifle | <<locked>> | 84% | 41,002 psi | 63% | 2828 fps | 95.8% |
| Shooters World Match Rifle | <<locked>> | 80% | 48,950 psi | 75% | 2995 fps | 100% |
| Shooters World Precision | <<locked>> | 80% | 43,903 psi | 68% | 2894 fps | 99.6% |
| Shooters World SW4350 | <<locked>> | 88% | 44,469 psi | 68% | 2923 fps | 95.6% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 40,292 psi | 62% | 2874 fps | 98.1% |
| SNPE Vectan SP 7 | <<locked>> | 80% | 49,937 psi | 77% | 3012 fps | 98.5% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 47,630 psi | 73% | 2982 fps | 99.4% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 49,124 psi | 76% | 2910 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 41,191 psi | 63% | 2759 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 86% | 43,149 psi | 66% | 2828 fps | 95% |
| Somchem S335 | <<locked>> | 80% | 48,863 psi | 75% | 2910 fps | 100% |
| Somchem S341 | <<locked>> | 80% | 49,443 psi | 76% | 3002 fps | 99.6% |
| Somchem S355 | <<locked>> | 80% | 39,885 psi | 61% | 2828 fps | 98.5% |
| Somchem S365 | <<locked>> | 80% | 29,240 psi | 45% | 2638 fps | 96.3% |
| Somchem S385 | <<locked>> | 96% | 46,586 psi | 72% | 2992 fps | 95.2% |
| Vihtavuori N130 | <<locked>> | 80% | 55,158 psi | 85% | 2969 fps | 100% |
| Vihtavuori N133 | <<locked>> | 80% | 49,545 psi | 76% | 2900 fps | 100% |
| Vihtavuori N135 | <<locked>> | 80% | 45,571 psi | 70% | 2890 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 45,919 psi | 71% | 2897 fps | 100% |
| Vihtavuori N150 | <<locked>> | 80% | 37,913 psi | 58% | 2753 fps | 99.1% |
| Vihtavuori N160 | <<locked>> | 82% | 36,361 psi | 56% | 2759 fps | 95.5% |
| Vihtavuori N530 | <<locked>> | 80% | 51,561 psi | 79% | 3022 fps | 100% |
| Vihtavuori N540 | <<locked>> | 80% | 44,396 psi | 68% | 2884 fps | 100% |
| Vihtavuori N550 | <<locked>> | 82% | 35,781 psi | 55% | 2756 fps | 95% |
| Vihtavuori N555 | <<locked>> | 88% | 33,069 psi | 51% | 2749 fps | 95.1% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 33,562 psi | 52% | 2671 fps | 97% |
| Winchester 748 | <<locked>> | 80% | 51,677 psi | 80% | 3071 fps | 100% |
| Winchester 760 | <<locked>> | 88% | 45,469 psi | 70% | 3002 fps | 95.6% |
| Winchester StaBALL HD | <<locked>> | 92% | 30,589 psi | 47% | 2753 fps | 95.7% |
| Winchester StaBALL Match | <<locked>> | 80% | 47,340 psi | 73% | 2989 fps | 99.6% |
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 117 powders for .280 Ackley Improved loaded with the .284 | 123gr | RWS Kegelspitz. ReloadSwiss RS 60 delivers the highest muzzle velocity at 3,294 fps; across all powders the maximum-charge window runs from 1,965 fps to 3,294 fps. Accurate 3100 gives the best case fill at 100 %, and 117 of the 117 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (448 MPa), the top charges use 55–90 %, leaving at least 10 % headroom. The 123.0 gr projectile in 0.284" calls for a 1:14.5 twist; slower twists will usually not stabilise this weight. Accurate 3100, Accurate MAGPRO, ADI AR 2209 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, Hodgdon Superformance, Alliant Reloder-17 rank at the top here: for .280 Ackley Improved with the .284 | 123gr | RWS Kegelspitz they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Accurate MAGPRO, ADI AR 2213, Alliant Reloder-22 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.