Load Specifications
Load data in caliber .260 Ackley Improved with .264 | 120gr | Frontier PH HPBT bullet and 96 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Alliant Power Pro 2000-MR, ReloadSwiss RS 60 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.
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 2015 | <<locked>> | 84% | 54,636 psi | 88% | 2769 fps | 100% |
| Accurate 2495 | <<locked>> | 88% | 53,171 psi | 85% | 2792 fps | 100% |
| Accurate 2520 | <<locked>> | 84% | 54,810 psi | 88% | 2854 fps | 100% |
| Accurate 2700 | <<locked>> | 90% | 56,144 psi | 90% | 2841 fps | 97% |
| Accurate 4064 | <<locked>> | 90% | 53,185 psi | 85% | 2838 fps | 100% |
| Accurate 4350 | <<locked>> | 98% | 52,562 psi | 84% | 2913 fps | 99.3% |
| ADI AR 2206H | <<locked>> | 86% | 53,824 psi | 86% | 2871 fps | 99.9% |
| ADI AR 2208 | <<locked>> | 92% | 54,810 psi | 88% | 2867 fps | 99.7% |
| ADI Benchmark 8208 | <<locked>> | 86% | 56,275 psi | 90% | 2871 fps | 100% |
| Alliant AR-Comp | <<locked>> | 84% | 53,417 psi | 86% | 2795 fps | 100% |
| Alliant Power Pro 2000-MR | <<locked>> | 88% | 53,200 psi | 85% | 2982 fps | 99.7% |
| Alliant Reloder- TS 15.5 | <<locked>> | 92% | 54,549 psi | 87% | 2887 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 90% | 55,288 psi | 89% | 2913 fps | 99.8% |
| Alliant Reloder-16ᴾ | <<locked>> | 100% | 54,288 psi | 87% | 2976 fps | 99.7% |
| Alliant Reloder-17 | <<locked>> | 96% | 55,564 psi | 89% | 3012 fps | 100% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 38,783 psi | 62% | 2703 fps | 98.4% |
| Alliant Reloder-26ᴾ | <<locked>> | 100% | 43,265 psi | 69% | 2861 fps | 97.6% |
| Baschieri & Pellagri 107 | <<locked>> | 86% | 53,606 psi | 86% | 2884 fps | 99.5% |
| Bofors RP3 | <<locked>> | 92% | 55,405 psi | 89% | 2907 fps | 100% |
| Bofors RP7 | <<locked>> | 96% | 55,361 psi | 89% | 2871 fps | 97.1% |
| Hodgdon Benchmark | <<locked>> | 84% | 54,592 psi | 88% | 2805 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 86% | 55,463 psi | 89% | 2900 fps | 100% |
| Hodgdon CFE223 | <<locked>> | 82% | 53,722 psi | 86% | 2943 fps | 99.7% |
| Hodgdon H380 | <<locked>> | 92% | 56,275 psi | 90% | 2917 fps | 99.4% |
| Hodgdon H414 | <<locked>> | 98% | 55,709 psi | 89% | 2966 fps | 97.9% |
| Hodgdon H4350 | <<locked>> | 94% | 53,084 psi | 85% | 2874 fps | 96% |
| Hodgdon H4895 | <<locked>> | 86% | 54,346 psi | 87% | 2881 fps | 100% |
| Hodgdon Hybrid 100Vᴾ | <<locked>> | 100% | 50,502 psi | 81% | 2851 fps | 99.9% |
| Hodgdon LEVERevolution | <<locked>> | 88% | 53,635 psi | 86% | 2913 fps | 100% |
| Hodgdon Superformance | <<locked>> | 96% | 52,866 psi | 85% | 2943 fps | 96.9% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 35,288 psi | 57% | 1755 fps | 100% |
| Hodgdon VARGET | <<locked>> | 88% | 55,666 psi | 89% | 2884 fps | 100% |
| IMR 3031 | <<locked>> | 86% | 54,389 psi | 87% | 2864 fps | 100% |
| IMR 4064 | <<locked>> | 90% | 54,259 psi | 87% | 2851 fps | 99.8% |
| IMR 4166 Enduron | <<locked>> | 88% | 54,346 psi | 87% | 2828 fps | 97.5% |
| IMR 4350ᴾ | <<locked>> | 100% | 55,593 psi | 89% | 2897 fps | 97.2% |
| IMR 4451 Enduron | <<locked>> | 94% | 53,925 psi | 86% | 2851 fps | 97.3% |
| IMR 4831ᴾ | <<locked>> | 100% | 53,548 psi | 86% | 2910 fps | 99.5% |
| IMR 4895 | <<locked>> | 88% | 53,272 psi | 85% | 2890 fps | 99.9% |
| IMR 8208 XBR | <<locked>> | 86% | 56,275 psi | 90% | 2871 fps | 100% |
| Lovex D073.6 | <<locked>> | 86% | 53,490 psi | 86% | 2844 fps | 100% |
| Lovex S060 | <<locked>> | 86% | 53,374 psi | 86% | 2795 fps | 99.9% |
| Lovex S062 | <<locked>> | 90% | 54,114 psi | 87% | 2848 fps | 100% |
| Lovex S065 | <<locked>> | 96% | 53,330 psi | 86% | 2848 fps | 98.5% |
| Lovex S070 | <<locked>> | 98% | 54,259 psi | 87% | 2881 fps | 97.7% |
| Norma 201 | <<locked>> | 88% | 55,825 psi | 90% | 2861 fps | 100% |
| Norma 202 | <<locked>> | 88% | 56,289 psi | 90% | 2864 fps | 100% |
| Norma 203B | <<locked>> | 90% | 54,462 psi | 87% | 2897 fps | 99.9% |
| Norma 204ᴾ | <<locked>> | 100% | 56,217 psi | 90% | 2943 fps | 96% |
| Norma URPᴾ | <<locked>> | 100% | 55,593 psi | 89% | 2959 fps | 99.6% |
| Ramshot Big Game | <<locked>> | 90% | 55,114 psi | 88% | 2923 fps | 99.9% |
| Ramshot Hunterᴾ | <<locked>> | 100% | 54,143 psi | 87% | 2949 fps | 98.4% |
| Ramshot TAC | <<locked>> | 86% | 56,391 psi | 90% | 2887 fps | 99% |
| Ramshot Wild Boar | <<locked>> | 86% | 56,289 psi | 90% | 2910 fps | 100% |
| Ramshot X-Terminator | <<locked>> | 82% | 53,679 psi | 86% | 2822 fps | 99.8% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 35,766 psi | 57% | 1798 fps | 100% |
| ReloadSwiss RS 40 | <<locked>> | 82% | 55,680 psi | 89% | 2851 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 90% | 52,910 psi | 85% | 2841 fps | 97.8% |
| ReloadSwiss RS 52 | <<locked>> | 88% | 55,738 psi | 89% | 2979 fps | 99.8% |
| ReloadSwiss RS 60 | <<locked>> | 94% | 55,158 psi | 88% | 3012 fps | 100% |
| ReloadSwiss RS 62ᴾ | <<locked>> | 100% | 56,028 psi | 90% | 2989 fps | 99.5% |
| ReloadSwiss RS 70ᴾ | <<locked>> | 100% | 55,869 psi | 90% | 3018 fps | 99.4% |
| Rottweil R 901 | <<locked>> | 84% | 53,795 psi | 86% | 2802 fps | 100% |
| Rottweil R 902 | <<locked>> | 90% | 56,289 psi | 90% | 2861 fps | 100% |
| Rottweil R 903 | <<locked>> | 94% | 55,274 psi | 89% | 2900 fps | 100% |
| Rottweil R 907 | <<locked>> | 96% | 55,361 psi | 89% | 2871 fps | 97.1% |
| Shooters World Long Rifle | <<locked>> | 96% | 53,330 psi | 86% | 2848 fps | 98.5% |
| Shooters World Match Rifle | <<locked>> | 86% | 53,490 psi | 86% | 2844 fps | 100% |
| Shooters World Precision | <<locked>> | 90% | 54,114 psi | 87% | 2848 fps | 100% |
| Shooters World SW4350 | <<locked>> | 98% | 54,259 psi | 87% | 2881 fps | 97.7% |
| SNPE Vectan SP 11 | <<locked>> | 92% | 53,388 psi | 86% | 2907 fps | 99.9% |
| SNPE Vectan SP 7 | <<locked>> | 86% | 54,882 psi | 88% | 2864 fps | 99.1% |
| SNPE Vectan SP 9 | <<locked>> | 88% | 55,637 psi | 89% | 2890 fps | 99.9% |
| SNPE Vectan Tubal 3000 | <<locked>> | 86% | 53,896 psi | 86% | 2753 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 92% | 54,128 psi | 87% | 2753 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 96% | 53,461 psi | 86% | 2795 fps | 97.3% |
| Somchem S321 | <<locked>> | 82% | 53,853 psi | 86% | 2851 fps | 100% |
| Somchem S335 | <<locked>> | 86% | 53,388 psi | 86% | 2753 fps | 100% |
| Somchem S341 | <<locked>> | 86% | 54,679 psi | 88% | 2861 fps | 99.9% |
| Somchem S355 | <<locked>> | 94% | 55,506 psi | 89% | 2894 fps | 100% |
| Somchem S365ᴾ | <<locked>> | 100% | 49,748 psi | 80% | 2907 fps | 100% |
| Vihtavuori N130 | <<locked>> | 82% | 53,766 psi | 86% | 2720 fps | 100% |
| Vihtavuori N133 | <<locked>> | 86% | 54,143 psi | 87% | 2740 fps | 100% |
| Vihtavuori N135 | <<locked>> | 90% | 56,188 psi | 90% | 2828 fps | 100% |
| Vihtavuori N140 | <<locked>> | 88% | 53,722 psi | 86% | 2799 fps | 100% |
| Vihtavuori N150 | <<locked>> | 94% | 53,606 psi | 86% | 2825 fps | 100% |
| Vihtavuori N160 | <<locked>> | 98% | 54,331 psi | 87% | 2897 fps | 99.4% |
| Vihtavuori N530 | <<locked>> | 84% | 53,258 psi | 85% | 2818 fps | 100% |
| Vihtavuori N540 | <<locked>> | 90% | 55,158 psi | 88% | 2841 fps | 100% |
| Vihtavuori N550 | <<locked>> | 98% | 53,490 psi | 86% | 2904 fps | 99.2% |
| Vihtavuori N555ᴾ | <<locked>> | 100% | 42,351 psi | 68% | 2782 fps | 98.4% |
| Winchester 6.5 StaBALL | <<locked>> | 98% | 54,752 psi | 88% | 2877 fps | 100% |
| Winchester 748 | <<locked>> | 84% | 53,200 psi | 85% | 2867 fps | 100% |
| Winchester 760 | <<locked>> | 98% | 56,130 psi | 90% | 2972 fps | 98% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 34,548 psi | 55% | 2694 fps | 98% |
| Winchester StaBALL Match | <<locked>> | 88% | 55,622 psi | 89% | 2900 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% | 48,457 psi | 78% | 2680 fps | 100% |
| Accurate 2495 | <<locked>> | 80% | 41,176 psi | 66% | 2605 fps | 100% |
| Accurate 2520 | <<locked>> | 80% | 47,921 psi | 77% | 2753 fps | 100% |
| Accurate 2700 | <<locked>> | 86% | 49,255 psi | 79% | 2730 fps | 95.6% |
| Accurate 4064 | <<locked>> | 80% | 38,914 psi | 62% | 2598 fps | 100% |
| Accurate 4350 | <<locked>> | 86% | 34,896 psi | 56% | 2575 fps | 95.5% |
| ADI AR 2206H | <<locked>> | 80% | 44,367 psi | 71% | 2707 fps | 99% |
| ADI AR 2208 | <<locked>> | 80% | 37,913 psi | 61% | 2556 fps | 97% |
| ADI Benchmark 8208 | <<locked>> | 80% | 46,398 psi | 74% | 2713 fps | 99.8% |
| Alliant AR-Comp | <<locked>> | 80% | 47,036 psi | 75% | 2707 fps | 100% |
| Alliant Power Pro 2000-MR | 38.8 gr | 80% | 40,364 psi | 65% | 2733 fps | 97.6% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 37,304 psi | 60% | 2575 fps | 98.4% |
| Alliant Reloder-15 | <<locked>> | 80% | 40,118 psi | 64% | 2638 fps | 97.8% |
| Alliant Reloder-16 | <<locked>> | 86% | 35,230 psi | 56% | 2589 fps | 95.6% |
| Alliant Reloder-17 | <<locked>> | 80% | 32,256 psi | 52% | 2536 fps | 96.3% |
| Alliant Reloder-23 | <<locked>> | 92% | 30,298 psi | 49% | 2480 fps | 95.1% |
| Alliant Reloder-26 | <<locked>> | 96% | 37,478 psi | 60% | 2726 fps | 95.6% |
| Baschieri & Pellagri 107 | <<locked>> | 80% | 43,656 psi | 70% | 2710 fps | 98.1% |
| Bofors RP3 | <<locked>> | 80% | 36,970 psi | 59% | 2579 fps | 98.4% |
| Bofors RP7 | <<locked>> | 90% | 45,847 psi | 74% | 2710 fps | 95% |
| Hodgdon Benchmark | <<locked>> | 80% | 48,327 psi | 77% | 2707 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 80% | 45,353 psi | 73% | 2736 fps | 99.9% |
| Hodgdon CFE223 | <<locked>> | 80% | 50,009 psi | 80% | 2881 fps | 99.4% |
| Hodgdon H380 | <<locked>> | 80% | 37,826 psi | 61% | 2582 fps | 95.8% |
| Hodgdon H414 | <<locked>> | 92% | 45,701 psi | 73% | 2795 fps | 95.8% |
| Hodgdon H4350 | <<locked>> | 92% | 49,908 psi | 80% | 2818 fps | 95.2% |
| Hodgdon H4895 | <<locked>> | 80% | 44,773 psi | 72% | 2717 fps | 99.4% |
| Hodgdon Hybrid 100V | <<locked>> | 84% | 30,197 psi | 48% | 2428 fps | 95.5% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 40,973 psi | 66% | 2690 fps | 99.2% |
| Hodgdon Superformance | 46.5 gr | 92% | 45,876 psi | 74% | 2815 fps | 95.1% |
| Hodgdon TrailBoss | <<locked>> | 80% | 26,440 psi | 42% | 1572 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 43,004 psi | 69% | 2667 fps | 99.1% |
| IMR 3031 | <<locked>> | 80% | 44,498 psi | 71% | 2713 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 39,784 psi | 64% | 2592 fps | 97.8% |
| IMR 4166 Enduron | <<locked>> | 82% | 44,904 psi | 72% | 2664 fps | 95.4% |
| IMR 4350 | <<locked>> | 94% | 46,151 psi | 74% | 2736 fps | 95.1% |
| IMR 4451 Enduron | <<locked>> | 88% | 44,904 psi | 72% | 2694 fps | 95.3% |
| IMR 4831 | <<locked>> | 86% | 33,692 psi | 54% | 2526 fps | 95.1% |
| IMR 4895 | <<locked>> | 80% | 41,075 psi | 66% | 2671 fps | 98.5% |
| IMR 8208 XBR | <<locked>> | 80% | 46,398 psi | 74% | 2713 fps | 99.8% |
| Lovex D073.6 | <<locked>> | 80% | 43,816 psi | 70% | 2690 fps | 100% |
| Lovex S060 | <<locked>> | 80% | 44,672 psi | 72% | 2648 fps | 99% |
| Lovex S062 | <<locked>> | 80% | 39,813 psi | 64% | 2598 fps | 99.1% |
| Lovex S065 | <<locked>> | 86% | 39,160 psi | 63% | 2585 fps | 95.3% |
| Lovex S070 | <<locked>> | 92% | 45,020 psi | 72% | 2723 fps | 95.7% |
| Norma 201 | <<locked>> | 80% | 43,758 psi | 70% | 2664 fps | 99.6% |
| Norma 202 | <<locked>> | 80% | 43,758 psi | 70% | 2667 fps | 100% |
| Norma 203B | <<locked>> | 80% | 39,479 psi | 63% | 2628 fps | 98.1% |
| Norma 204 | <<locked>> | 98% | 52,736 psi | 85% | 2887 fps | 95.2% |
| Norma URP | <<locked>> | 86% | 35,027 psi | 56% | 2569 fps | 95.3% |
| Ramshot Big Game | <<locked>> | 80% | 39,044 psi | 63% | 2641 fps | 97.9% |
| Ramshot Hunter | <<locked>> | 92% | 41,858 psi | 67% | 2726 fps | 95.6% |
| Ramshot TAC | <<locked>> | 80% | 46,499 psi | 75% | 2720 fps | 97.4% |
| Ramshot Wild Boar | <<locked>> | 80% | 45,861 psi | 74% | 2740 fps | 99.2% |
| Ramshot X-Terminator | <<locked>> | 80% | 50,227 psi | 81% | 2766 fps | 99.6% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 26,672 psi | 43% | 1608 fps | 100% |
| ReloadSwiss RS 40 | <<locked>> | 80% | 52,330 psi | 84% | 2802 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 82% | 41,075 psi | 66% | 2625 fps | 95% |
| ReloadSwiss RS 52 | <<locked>> | 80% | 42,134 psi | 68% | 2743 fps | 98.2% |
| ReloadSwiss RS 60 | 38.2 gr | 80% | 34,345 psi | 55% | 2608 fps | 99.2% |
| ReloadSwiss RS 62 | <<locked>> | 88% | 37,043 psi | 59% | 2644 fps | 95.8% |
| ReloadSwiss RS 70 | <<locked>> | 90% | 39,885 psi | 64% | 2713 fps | 95.9% |
| Rottweil R 901 | <<locked>> | 80% | 47,500 psi | 76% | 2703 fps | 100% |
| Rottweil R 902 | <<locked>> | 80% | 41,423 psi | 66% | 2612 fps | 99.3% |
| Rottweil R 903 | <<locked>> | 80% | 34,766 psi | 56% | 2523 fps | 97.5% |
| Rottweil R 907 | <<locked>> | 90% | 45,847 psi | 74% | 2710 fps | 95% |
| Shooters World Long Rifle | <<locked>> | 86% | 39,160 psi | 63% | 2585 fps | 95.3% |
| Shooters World Match Rifle | <<locked>> | 80% | 43,816 psi | 70% | 2690 fps | 100% |
| Shooters World Precision | <<locked>> | 80% | 39,813 psi | 64% | 2598 fps | 99.1% |
| Shooters World SW4350 | <<locked>> | 92% | 45,020 psi | 72% | 2723 fps | 95.7% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 35,737 psi | 57% | 2572 fps | 97% |
| SNPE Vectan SP 7 | <<locked>> | 80% | 44,788 psi | 72% | 2697 fps | 97.6% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 42,902 psi | 69% | 2674 fps | 98.7% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 45,078 psi | 72% | 2618 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 37,507 psi | 60% | 2484 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 90% | 44,048 psi | 71% | 2638 fps | 95.2% |
| Somchem S321 | <<locked>> | 80% | 50,343 psi | 81% | 2795 fps | 100% |
| Somchem S335 | <<locked>> | 80% | 44,730 psi | 72% | 2618 fps | 100% |
| Somchem S341 | <<locked>> | 80% | 44,425 psi | 71% | 2690 fps | 98.9% |
| Somchem S355 | <<locked>> | 80% | 35,882 psi | 58% | 2536 fps | 97.6% |
| Somchem S365 | <<locked>> | 82% | 27,731 psi | 44% | 2411 fps | 95.9% |
| Vihtavuori N130 | <<locked>> | 80% | 50,850 psi | 82% | 2677 fps | 100% |
| Vihtavuori N133 | <<locked>> | 80% | 45,397 psi | 73% | 2612 fps | 100% |
| Vihtavuori N135 | <<locked>> | 80% | 41,060 psi | 66% | 2598 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 41,408 psi | 66% | 2602 fps | 100% |
| Vihtavuori N150 | <<locked>> | 80% | 33,881 psi | 54% | 2467 fps | 98.3% |
| Vihtavuori N160 | <<locked>> | 84% | 34,548 psi | 55% | 2523 fps | 95% |
| Vihtavuori N530 | <<locked>> | 80% | 46,499 psi | 75% | 2710 fps | 99.8% |
| Vihtavuori N540 | <<locked>> | 80% | 39,914 psi | 64% | 2592 fps | 100% |
| Vihtavuori N550 | <<locked>> | 86% | 36,100 psi | 58% | 2575 fps | 95.4% |
| Vihtavuori N555 | <<locked>> | 92% | 32,547 psi | 52% | 2562 fps | 95.3% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 30,110 psi | 48% | 2388 fps | 95.5% |
| Winchester 748 | <<locked>> | 80% | 46,166 psi | 74% | 2756 fps | 100% |
| Winchester 760 | <<locked>> | 92% | 45,701 psi | 73% | 2795 fps | 95.8% |
| Winchester StaBALL HD | <<locked>> | 96% | 30,545 psi | 49% | 2566 fps | 95.8% |
| Winchester StaBALL Match | <<locked>> | 80% | 42,395 psi | 68% | 2680 fps | 99.1% |
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 .260 Ackley Improved loaded with the .264 | 120gr | Frontier PH HPBT. ReloadSwiss RS 70 delivers the highest muzzle velocity at 3,018 fps; across all powders the maximum-charge window runs from 1,755 fps to 3,018 fps. Alliant Reloder-16 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 (430 MPa), the top charges use 55–90 %, leaving at least 10 % headroom. The 120.0 gr projectile in 0.264" calls for a 1:9.5 twist; slower twists will usually not stabilise this weight. Alliant Reloder-16, 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. Alliant Power Pro 2000-MR, ReloadSwiss RS 60, Hodgdon Superformance rank at the top here: for .260 Ackley Improved with the .264 | 120gr | Frontier PH HPBT 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.