Load Specifications
Load data in caliber .280 Ackley Improved with .284 | 120gr | Sierra Pro-Hunter bullet and 96 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-17 and ReloadSwiss RS 60.
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% | 56,579 psi | 87% | 3068 fps | 100% |
| Accurate 2495 | <<locked>> | 86% | 56,086 psi | 86% | 3091 fps | 100% |
| Accurate 2520 | <<locked>> | 82% | 57,363 psi | 88% | 3159 fps | 100% |
| Accurate 2700 | <<locked>> | 88% | 58,262 psi | 90% | 3150 fps | 97.4% |
| Accurate 3100ᴾ | <<locked>> | 100% | 47,282 psi | 73% | 3038 fps | 97% |
| Accurate 4064 | <<locked>> | 88% | 56,260 psi | 87% | 3143 fps | 100% |
| Accurate 4350 | <<locked>> | 96% | 56,739 psi | 87% | 3238 fps | 99.6% |
| ADI AR 2206H | <<locked>> | 84% | 55,738 psi | 86% | 3173 fps | 99.9% |
| ADI AR 2208 | <<locked>> | 90% | 56,855 psi | 87% | 3173 fps | 99.8% |
| ADI Benchmark 8208 | <<locked>> | 84% | 58,059 psi | 89% | 3173 fps | 100% |
| Alliant AR-Comp | <<locked>> | 82% | 55,782 psi | 86% | 3094 fps | 100% |
| Alliant Power Pro 2000-MR | <<locked>> | 86% | 55,912 psi | 86% | 3301 fps | 99.8% |
| Alliant Reloder- TS 15.5 | <<locked>> | 90% | 57,421 psi | 88% | 3199 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 88% | 57,986 psi | 89% | 3225 fps | 99.9% |
| Alliant Reloder-16 | <<locked>> | 98% | 57,595 psi | 89% | 3301 fps | 99.9% |
| Alliant Reloder-17 | <<locked>> | 92% | 55,390 psi | 85% | 3278 fps | 100% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 44,324 psi | 68% | 3061 fps | 99.4% |
| Alliant Reloder-26ᴾ | <<locked>> | 100% | 50,618 psi | 78% | 3258 fps | 99.1% |
| Baschieri & Pellagri 107 | <<locked>> | 84% | 55,767 psi | 86% | 3186 fps | 99.6% |
| Bofors RP3 | <<locked>> | 90% | 58,392 psi | 90% | 3219 fps | 100% |
| Bofors RP7 | <<locked>> | 94% | 58,088 psi | 89% | 3189 fps | 97.6% |
| Hodgdon Benchmark | <<locked>> | 82% | 56,043 psi | 86% | 3100 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 84% | 58,117 psi | 89% | 3205 fps | 100% |
| Hodgdon H380 | <<locked>> | 88% | 55,317 psi | 85% | 3173 fps | 99.2% |
| Hodgdon H414 | <<locked>> | 94% | 55,492 psi | 85% | 3228 fps | 97.8% |
| Hodgdon H4350 | <<locked>> | 92% | 55,883 psi | 86% | 3192 fps | 96.6% |
| Hodgdon H4895 | <<locked>> | 84% | 56,347 psi | 87% | 3186 fps | 100% |
| Hodgdon Hybrid 100Vᴾ | <<locked>> | 100% | 57,653 psi | 89% | 3219 fps | 100% |
| Hodgdon LEVERevolution | <<locked>> | 86% | 56,521 psi | 87% | 3222 fps | 100% |
| Hodgdon Superformance | <<locked>> | 94% | 56,086 psi | 86% | 3264 fps | 97.6% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 35,853 psi | 55% | 1995 fps | 100% |
| Hodgdon VARGET | <<locked>> | 86% | 57,696 psi | 89% | 3189 fps | 100% |
| IMR 3031 | <<locked>> | 84% | 56,840 psi | 87% | 3173 fps | 100% |
| IMR 4064 | <<locked>> | 88% | 56,536 psi | 87% | 3159 fps | 99.9% |
| IMR 4166 Enduron | <<locked>> | 86% | 56,014 psi | 86% | 3133 fps | 97.8% |
| IMR 4350 | <<locked>> | 98% | 58,697 psi | 90% | 3215 fps | 97.8% |
| IMR 4451 Enduron | <<locked>> | 92% | 56,318 psi | 87% | 3163 fps | 97.7% |
| IMR 4831 | <<locked>> | 98% | 57,145 psi | 88% | 3225 fps | 99.7% |
| IMR 4895 | <<locked>> | 86% | 55,579 psi | 86% | 3199 fps | 99.9% |
| IMR 8208 XBR | <<locked>> | 84% | 58,059 psi | 89% | 3173 fps | 100% |
| Lovex D073.6 | <<locked>> | 84% | 56,014 psi | 86% | 3146 fps | 100% |
| Lovex S060 | <<locked>> | 86% | 58,320 psi | 90% | 3150 fps | 100% |
| Lovex S062 | <<locked>> | 88% | 56,492 psi | 87% | 3156 fps | 100% |
| Lovex S065 | <<locked>> | 94% | 56,014 psi | 86% | 3159 fps | 98.8% |
| Lovex S070 | <<locked>> | 96% | 57,058 psi | 88% | 3192 fps | 98.2% |
| Norma 201 | <<locked>> | 86% | 58,030 psi | 89% | 3173 fps | 100% |
| Norma 202 | <<locked>> | 86% | 58,697 psi | 90% | 3169 fps | 100% |
| Norma 203B | <<locked>> | 88% | 57,203 psi | 88% | 3209 fps | 100% |
| Norma 204 | <<locked>> | 96% | 55,927 psi | 86% | 3209 fps | 96% |
| Norma MRPᴾ | <<locked>> | 100% | 49,937 psi | 77% | 3202 fps | 96.6% |
| Norma URP | <<locked>> | 96% | 55,419 psi | 85% | 3219 fps | 99.5% |
| Ramshot Big Game | <<locked>> | 88% | 57,957 psi | 89% | 3235 fps | 100% |
| Ramshot Hunter | <<locked>> | 98% | 58,015 psi | 89% | 3274 fps | 98.9% |
| Ramshot TAC | <<locked>> | 84% | 58,697 psi | 90% | 3199 fps | 99.2% |
| Ramshot Wild Boar | <<locked>> | 84% | 58,479 psi | 90% | 3215 fps | 100% |
| Ramshot X-Terminator | <<locked>> | 82% | 58,813 psi | 90% | 3173 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 36,347 psi | 56% | 2041 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 88% | 55,506 psi | 85% | 3150 fps | 98.2% |
| ReloadSwiss RS 52 | <<locked>> | 84% | 54,868 psi | 84% | 3235 fps | 99.7% |
| ReloadSwiss RS 60 | <<locked>> | 90% | 54,897 psi | 84% | 3274 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 96% | 56,826 psi | 87% | 3261 fps | 99.5% |
| ReloadSwiss RS 70 | <<locked>> | 96% | 55,782 psi | 86% | 3291 fps | 99.4% |
| Rottweil R 901 | <<locked>> | 82% | 55,347 psi | 85% | 3097 fps | 100% |
| Rottweil R 902 | <<locked>> | 88% | 58,653 psi | 90% | 3173 fps | 100% |
| Rottweil R 903 | <<locked>> | 92% | 58,247 psi | 90% | 3209 fps | 100% |
| Rottweil R 907 | <<locked>> | 94% | 58,088 psi | 89% | 3189 fps | 97.6% |
| Shooters World Long Rifle | <<locked>> | 94% | 56,014 psi | 86% | 3159 fps | 98.8% |
| Shooters World Match Rifle | <<locked>> | 84% | 56,014 psi | 86% | 3146 fps | 100% |
| Shooters World Precision | <<locked>> | 88% | 56,492 psi | 87% | 3156 fps | 100% |
| Shooters World SW4350 | <<locked>> | 96% | 57,058 psi | 88% | 3192 fps | 98.2% |
| SNPE Vectan SP 11 | <<locked>> | 90% | 56,376 psi | 87% | 3215 fps | 99.9% |
| SNPE Vectan SP 7 | <<locked>> | 84% | 57,406 psi | 88% | 3176 fps | 99.4% |
| SNPE Vectan SP 9 | <<locked>> | 86% | 57,943 psi | 89% | 3199 fps | 100% |
| SNPE Vectan Tubal 3000 | <<locked>> | 84% | 55,593 psi | 86% | 3051 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 90% | 56,420 psi | 87% | 3051 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 94% | 55,941 psi | 86% | 3100 fps | 97.8% |
| Somchem S335 | <<locked>> | 86% | 58,639 psi | 90% | 3097 fps | 100% |
| Somchem S341 | <<locked>> | 84% | 56,797 psi | 87% | 3159 fps | 100% |
| Somchem S355 | <<locked>> | 92% | 58,363 psi | 90% | 3205 fps | 100% |
| Somchem S365ᴾ | <<locked>> | 100% | 57,943 psi | 89% | 3281 fps | 100% |
| Somchem S385ᴾ | <<locked>> | 100% | 53,417 psi | 82% | 3153 fps | 96.8% |
| Vihtavuori N130 | <<locked>> | 82% | 58,697 psi | 90% | 3058 fps | 100% |
| Vihtavuori N133 | <<locked>> | 84% | 55,970 psi | 86% | 3035 fps | 100% |
| Vihtavuori N135 | <<locked>> | 88% | 58,639 psi | 90% | 3130 fps | 100% |
| Vihtavuori N140 | <<locked>> | 86% | 55,680 psi | 86% | 3094 fps | 100% |
| Vihtavuori N150 | <<locked>> | 92% | 56,144 psi | 86% | 3127 fps | 100% |
| Vihtavuori N160 | <<locked>> | 96% | 57,885 psi | 89% | 3219 fps | 99.7% |
| Vihtavuori N530 | <<locked>> | 84% | 58,697 psi | 90% | 3176 fps | 100% |
| Vihtavuori N540 | <<locked>> | 88% | 57,537 psi | 89% | 3136 fps | 100% |
| Vihtavuori N550 | <<locked>> | 96% | 57,072 psi | 88% | 3222 fps | 99.5% |
| Vihtavuori N555ᴾ | <<locked>> | 100% | 49,574 psi | 76% | 3153 fps | 99.3% |
| Winchester 6.5 StaBALL | <<locked>> | 96% | 58,088 psi | 89% | 3189 fps | 100% |
| Winchester 748 | <<locked>> | 82% | 55,347 psi | 85% | 3169 fps | 100% |
| Winchester 760 | <<locked>> | 94% | 55,782 psi | 86% | 3232 fps | 97.8% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 39,972 psi | 61% | 3081 fps | 99.5% |
| Winchester StaBALL Match | <<locked>> | 86% | 58,059 psi | 89% | 3205 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% | 53,098 psi | 82% | 3015 fps | 100% |
| Accurate 2495 | <<locked>> | 80% | 45,963 psi | 71% | 2933 fps | 100% |
| Accurate 2520 | <<locked>> | 80% | 53,795 psi | 83% | 3104 fps | 100% |
| Accurate 2700 | <<locked>> | 82% | 47,863 psi | 74% | 2966 fps | 95.2% |
| Accurate 3100 | <<locked>> | 96% | 40,973 psi | 63% | 2907 fps | 95.2% |
| Accurate 4064 | <<locked>> | 80% | 43,497 psi | 67% | 2927 fps | 100% |
| Accurate 4350 | <<locked>> | 84% | 37,318 psi | 57% | 2851 fps | 95.9% |
| ADI AR 2206H | <<locked>> | 80% | 49,168 psi | 76% | 3054 fps | 99.5% |
| ADI AR 2208 | <<locked>> | 80% | 41,640 psi | 64% | 2881 fps | 97.7% |
| ADI Benchmark 8208 | <<locked>> | 80% | 51,271 psi | 79% | 3064 fps | 100% |
| Alliant AR-Comp | <<locked>> | 80% | 52,431 psi | 81% | 3045 fps | 100% |
| Alliant Power Pro 2000-MR | <<locked>> | 80% | 45,223 psi | 70% | 3094 fps | 98.5% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 41,698 psi | 64% | 2910 fps | 99% |
| Alliant Reloder-15 | <<locked>> | 80% | 44,788 psi | 69% | 2982 fps | 98.5% |
| Alliant Reloder-16 | <<locked>> | 84% | 36,825 psi | 57% | 2864 fps | 95.9% |
| Alliant Reloder-17 | 55.3 gr | 80% | 36,419 psi | 56% | 2881 fps | 97.5% |
| Alliant Reloder-23 | <<locked>> | 90% | 32,300 psi | 50% | 2756 fps | 95.7% |
| Alliant Reloder-26 | <<locked>> | 92% | 37,739 psi | 58% | 2963 fps | 95.4% |
| Baschieri & Pellagri 107 | <<locked>> | 80% | 48,733 psi | 75% | 3058 fps | 98.8% |
| Bofors RP3 | <<locked>> | 80% | 41,872 psi | 64% | 2920 fps | 99.1% |
| Bofors RP7 | <<locked>> | 88% | 48,022 psi | 74% | 3009 fps | 95.5% |
| Hodgdon Benchmark | <<locked>> | 80% | 52,678 psi | 81% | 3048 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 80% | 50,734 psi | 78% | 3087 fps | 100% |
| Hodgdon H380 | <<locked>> | 80% | 42,322 psi | 65% | 2920 fps | 96.9% |
| Hodgdon H414 | <<locked>> | 88% | 45,513 psi | 70% | 3035 fps | 95.5% |
| Hodgdon H4350 | <<locked>> | 90% | 52,228 psi | 80% | 3127 fps | 95.7% |
| Hodgdon H4895 | <<locked>> | 80% | 49,676 psi | 76% | 3068 fps | 99.7% |
| Hodgdon Hybrid 100V | <<locked>> | 82% | 31,792 psi | 49% | 2687 fps | 95.8% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 45,919 psi | 71% | 3035 fps | 99.6% |
| Hodgdon Superformance | <<locked>> | 90% | 48,457 psi | 75% | 3123 fps | 95.8% |
| Hodgdon TrailBoss | <<locked>> | 80% | 26,803 psi | 41% | 1788 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 47,500 psi | 73% | 3012 fps | 99.5% |
| IMR 3031 | <<locked>> | 80% | 49,719 psi | 76% | 3058 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 43,758 psi | 67% | 2923 fps | 98.4% |
| IMR 4166 Enduron | <<locked>> | 80% | 46,253 psi | 71% | 2949 fps | 95.6% |
| IMR 4350 | <<locked>> | 92% | 48,660 psi | 75% | 3038 fps | 95.7% |
| IMR 4451 Enduron | <<locked>> | 86% | 46,775 psi | 72% | 2982 fps | 95.6% |
| IMR 4831 | <<locked>> | 84% | 36,085 psi | 56% | 2805 fps | 95.5% |
| IMR 4895 | <<locked>> | 80% | 45,905 psi | 71% | 3018 fps | 99.1% |
| IMR 8208 XBR | <<locked>> | 80% | 51,271 psi | 79% | 3064 fps | 100% |
| Lovex D073.6 | <<locked>> | 80% | 48,936 psi | 75% | 3031 fps | 100% |
| Lovex S060 | <<locked>> | 80% | 48,660 psi | 75% | 2986 fps | 99.5% |
| Lovex S062 | <<locked>> | 80% | 44,034 psi | 68% | 2930 fps | 99.6% |
| Lovex S065 | <<locked>> | 84% | 41,002 psi | 63% | 2864 fps | 95.6% |
| Lovex S070 | <<locked>> | 88% | 44,353 psi | 68% | 2953 fps | 95.4% |
| Norma 201 | <<locked>> | 80% | 47,993 psi | 74% | 2999 fps | 99.9% |
| Norma 202 | <<locked>> | 80% | 48,501 psi | 75% | 3005 fps | 100% |
| Norma 203B | <<locked>> | 80% | 44,135 psi | 68% | 2972 fps | 98.8% |
| Norma 204 | <<locked>> | 94% | 52,083 psi | 80% | 3140 fps | 95.1% |
| Norma MRP | <<locked>> | 98% | 46,746 psi | 72% | 3136 fps | 95.7% |
| Norma URP | <<locked>> | 84% | 37,318 psi | 57% | 2851 fps | 95.8% |
| Ramshot Big Game | <<locked>> | 80% | 44,019 psi | 68% | 2986 fps | 98.7% |
| Ramshot Hunter | <<locked>> | 88% | 41,481 psi | 64% | 2953 fps | 95.2% |
| Ramshot TAC | <<locked>> | 80% | 51,271 psi | 79% | 3071 fps | 98.2% |
| Ramshot Wild Boar | <<locked>> | 80% | 51,126 psi | 79% | 3094 fps | 99.7% |
| Ramshot X-Terminator | <<locked>> | 80% | 55,129 psi | 85% | 3114 fps | 99.9% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 27,108 psi | 42% | 1827 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 42,612 psi | 66% | 2900 fps | 95.3% |
| ReloadSwiss RS 52 | <<locked>> | 80% | 47,761 psi | 73% | 3107 fps | 99% |
| ReloadSwiss RS 60 | 55.3 gr | 80% | 38,740 psi | 60% | 2956 fps | 99.8% |
| ReloadSwiss RS 62 | <<locked>> | 84% | 37,159 psi | 57% | 2867 fps | 95.4% |
| ReloadSwiss RS 70 | 60.3 gr | 86% | 39,218 psi | 60% | 2940 fps | 95.5% |
| Rottweil R 901 | <<locked>> | 80% | 52,214 psi | 80% | 3048 fps | 100% |
| Rottweil R 902 | <<locked>> | 80% | 45,774 psi | 70% | 2949 fps | 99.7% |
| Rottweil R 903 | <<locked>> | 80% | 39,218 psi | 60% | 2854 fps | 98.4% |
| Rottweil R 907 | <<locked>> | 88% | 48,022 psi | 74% | 3009 fps | 95.5% |
| Shooters World Long Rifle | <<locked>> | 84% | 41,002 psi | 63% | 2864 fps | 95.6% |
| Shooters World Match Rifle | <<locked>> | 80% | 48,936 psi | 75% | 3031 fps | 100% |
| Shooters World Precision | <<locked>> | 80% | 44,034 psi | 68% | 2930 fps | 99.6% |
| Shooters World SW4350 | <<locked>> | 88% | 44,353 psi | 68% | 2953 fps | 95.4% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 40,292 psi | 62% | 2907 fps | 97.9% |
| SNPE Vectan SP 7 | <<locked>> | 80% | 49,835 psi | 77% | 3045 fps | 98.4% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 47,659 psi | 73% | 3018 fps | 99.3% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 49,052 psi | 75% | 2946 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 41,147 psi | 63% | 2795 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 88% | 46,122 psi | 71% | 2927 fps | 95.7% |
| Somchem S335 | <<locked>> | 80% | 48,747 psi | 75% | 2943 fps | 100% |
| Somchem S341 | <<locked>> | 80% | 49,603 psi | 76% | 3041 fps | 99.5% |
| Somchem S355 | <<locked>> | 80% | 39,784 psi | 61% | 2858 fps | 98.3% |
| Somchem S365 | <<locked>> | 80% | 29,283 psi | 45% | 2671 fps | 96.1% |
| Somchem S385 | <<locked>> | 96% | 46,688 psi | 72% | 3025 fps | 95.1% |
| Vihtavuori N130 | <<locked>> | 80% | 55,114 psi | 85% | 3009 fps | 100% |
| Vihtavuori N133 | <<locked>> | 80% | 49,501 psi | 76% | 2936 fps | 100% |
| Vihtavuori N135 | <<locked>> | 80% | 45,498 psi | 70% | 2923 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 45,977 psi | 71% | 2933 fps | 100% |
| Vihtavuori N150 | <<locked>> | 80% | 37,985 psi | 58% | 2789 fps | 99% |
| Vihtavuori N160 | <<locked>> | 82% | 36,361 psi | 56% | 2795 fps | 95.3% |
| Vihtavuori N530 | <<locked>> | 80% | 51,605 psi | 79% | 3061 fps | 100% |
| Vihtavuori N540 | <<locked>> | 80% | 44,411 psi | 68% | 2917 fps | 100% |
| Vihtavuori N550 | <<locked>> | 84% | 38,348 psi | 59% | 2854 fps | 95.8% |
| Vihtavuori N555 | <<locked>> | 90% | 35,346 psi | 54% | 2841 fps | 95.9% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 33,663 psi | 52% | 2703 fps | 96.8% |
| Winchester 748 | <<locked>> | 80% | 51,880 psi | 80% | 3114 fps | 100% |
| Winchester 760 | <<locked>> | 88% | 45,513 psi | 70% | 3035 fps | 95.5% |
| Winchester StaBALL HD | <<locked>> | 92% | 30,676 psi | 47% | 2782 fps | 95.5% |
| Winchester StaBALL Match | <<locked>> | 80% | 47,558 psi | 73% | 3028 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 96 powders for .280 Ackley Improved loaded with the .284 | 120gr | Sierra Pro-Hunter. Alliant Power Pro 2000-MR delivers the highest muzzle velocity at 3,301 fps; across all powders the maximum-charge window runs from 1,995 fps to 3,301 fps. Accurate 3100 gives the best case fill at 100 %, and 96 of the 96 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 120.0 gr projectile in 0.284" calls for a 1:16.0 twist; slower twists will usually not stabilise this weight. Accurate 3100, Alliant Reloder-23, Alliant Reloder-26 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-17, ReloadSwiss RS 60 rank at the top here: for .280 Ackley Improved with the .284 | 120gr | Sierra Pro-Hunter 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.