Load Specifications
Load data in caliber .260 Ackley Improved with .264 | 130gr | Swift Scirocco bullet and 97 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Alliant Reloder-17, ReloadSwiss RS 60 and Hodgdon H414.
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>> | 84% | 55,999 psi | 90% | 2664 fps | 100% |
| Accurate 2495 | <<locked>> | 88% | 54,723 psi | 88% | 2687 fps | 100% |
| Accurate 2520 | <<locked>> | 82% | 52,881 psi | 85% | 2707 fps | 100% |
| Accurate 2700 | <<locked>> | 88% | 53,635 psi | 86% | 2690 fps | 97.2% |
| Accurate 3100ᴾ | <<locked>> | 100% | 41,597 psi | 67% | 2592 fps | 96.4% |
| Accurate 4064 | <<locked>> | 90% | 54,868 psi | 88% | 2740 fps | 100% |
| Accurate 4350 | <<locked>> | 98% | 54,708 psi | 88% | 2825 fps | 99.8% |
| ADI AR 2206H | <<locked>> | 86% | 55,143 psi | 88% | 2769 fps | 100% |
| ADI AR 2208 | <<locked>> | 92% | 55,956 psi | 90% | 2766 fps | 99.9% |
| ADI Benchmark 8208 | <<locked>> | 84% | 54,041 psi | 87% | 2720 fps | 100% |
| Alliant AR-Comp | <<locked>> | 84% | 55,027 psi | 88% | 2690 fps | 100% |
| Alliant Power Pro 2000-MR | <<locked>> | 88% | 54,737 psi | 88% | 2887 fps | 100% |
| Alliant Reloder- TS 15.5 | <<locked>> | 92% | 56,275 psi | 90% | 2792 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 88% | 53,476 psi | 86% | 2766 fps | 99.9% |
| Alliant Reloder-16ᴾ | <<locked>> | 100% | 55,666 psi | 89% | 2877 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 94% | 53,214 psi | 85% | 2858 fps | 100% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 39,943 psi | 64% | 2625 fps | 99.2% |
| Alliant Reloder-26ᴾ | <<locked>> | 100% | 44,483 psi | 71% | 2782 fps | 98.6% |
| Baschieri & Pellagri 107 | <<locked>> | 86% | 55,027 psi | 88% | 2785 fps | 99.8% |
| Bofors RP3 | <<locked>> | 90% | 53,374 psi | 86% | 2756 fps | 100% |
| Bofors RP7 | <<locked>> | 94% | 53,272 psi | 85% | 2726 fps | 97.4% |
| Hodgdon Benchmark | <<locked>> | 84% | 55,579 psi | 89% | 2700 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 84% | 53,330 psi | 86% | 2749 fps | 100% |
| Hodgdon CFE223 | <<locked>> | 82% | 55,448 psi | 89% | 2844 fps | 100% |
| Hodgdon H380 | <<locked>> | 90% | 54,172 psi | 87% | 2769 fps | 99.5% |
| Hodgdon H414 | <<locked>> | 96% | 53,824 psi | 86% | 2822 fps | 98.1% |
| Hodgdon H4350 | <<locked>> | 94% | 54,665 psi | 88% | 2785 fps | 97% |
| Hodgdon H4895 | <<locked>> | 86% | 55,753 psi | 89% | 2779 fps | 100% |
| Hodgdon Hybrid 100Vᴾ | <<locked>> | 100% | 51,909 psi | 83% | 2753 fps | 100% |
| Hodgdon LEVERevolution | <<locked>> | 88% | 55,187 psi | 88% | 2812 fps | 100% |
| Hodgdon Superformance | <<locked>> | 96% | 54,389 psi | 87% | 2854 fps | 97.8% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 35,592 psi | 57% | 1677 fps | 100% |
| Hodgdon VARGET | <<locked>> | 86% | 53,577 psi | 86% | 2733 fps | 100% |
| IMR 3031 | <<locked>> | 86% | 55,724 psi | 89% | 2756 fps | 100% |
| IMR 4064 | <<locked>> | 90% | 55,695 psi | 89% | 2753 fps | 100% |
| IMR 4166 Enduron | <<locked>> | 88% | 55,361 psi | 89% | 2730 fps | 98.2% |
| IMR 4350 | <<locked>> | 98% | 53,519 psi | 86% | 2753 fps | 97.5% |
| IMR 4451 Enduron | <<locked>> | 94% | 55,230 psi | 89% | 2759 fps | 98.1% |
| IMR 4831ᴾ | <<locked>> | 100% | 55,230 psi | 89% | 2815 fps | 99.8% |
| IMR 4895 | <<locked>> | 88% | 54,766 psi | 88% | 2792 fps | 100% |
| IMR 8208 XBR | <<locked>> | 84% | 54,041 psi | 87% | 2720 fps | 100% |
| Lovex D073.6 | <<locked>> | 86% | 54,752 psi | 88% | 2740 fps | 100% |
| Lovex S060 | <<locked>> | 86% | 54,766 psi | 88% | 2700 fps | 100% |
| Lovex S062 | <<locked>> | 90% | 55,622 psi | 89% | 2749 fps | 100% |
| Lovex S065 | <<locked>> | 96% | 54,795 psi | 88% | 2753 fps | 99.1% |
| Lovex S070 | <<locked>> | 98% | 55,608 psi | 89% | 2789 fps | 98.5% |
| Norma 201 | <<locked>> | 86% | 54,027 psi | 87% | 2717 fps | 100% |
| Norma 202 | <<locked>> | 86% | 54,520 psi | 87% | 2717 fps | 100% |
| Norma 203B | <<locked>> | 90% | 55,767 psi | 89% | 2795 fps | 100% |
| Norma 204 | <<locked>> | 98% | 54,288 psi | 87% | 2802 fps | 96.3% |
| Norma URP | <<locked>> | 98% | 53,577 psi | 86% | 2812 fps | 99.7% |
| Ramshot Big Game | <<locked>> | 88% | 52,939 psi | 85% | 2776 fps | 100% |
| Ramshot Hunterᴾ | <<locked>> | 100% | 55,999 psi | 90% | 2861 fps | 99.1% |
| Ramshot TAC | <<locked>> | 84% | 54,273 psi | 87% | 2740 fps | 99.1% |
| Ramshot Wild Boar | <<locked>> | 84% | 53,795 psi | 86% | 2753 fps | 100% |
| Ramshot X-Terminator | <<locked>> | 82% | 55,027 psi | 88% | 2723 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 36,129 psi | 58% | 1716 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 90% | 54,331 psi | 87% | 2749 fps | 98.6% |
| ReloadSwiss RS 52 | <<locked>> | 86% | 53,606 psi | 86% | 2825 fps | 99.9% |
| ReloadSwiss RS 60 | <<locked>> | 92% | 53,084 psi | 85% | 2858 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 98% | 54,085 psi | 87% | 2844 fps | 99.6% |
| ReloadSwiss RS 70 | <<locked>> | 98% | 53,824 psi | 86% | 2874 fps | 99.5% |
| Rottweil R 901 | <<locked>> | 84% | 55,071 psi | 88% | 2697 fps | 100% |
| Rottweil R 902 | <<locked>> | 88% | 54,476 psi | 87% | 2713 fps | 100% |
| Rottweil R 903 | <<locked>> | 92% | 53,258 psi | 85% | 2749 fps | 100% |
| Rottweil R 907 | <<locked>> | 94% | 53,272 psi | 85% | 2726 fps | 97.4% |
| Shooters World Long Rifle | <<locked>> | 96% | 54,795 psi | 88% | 2753 fps | 99.1% |
| Shooters World Match Rifle | <<locked>> | 86% | 54,752 psi | 88% | 2740 fps | 100% |
| Shooters World Precision | <<locked>> | 90% | 55,622 psi | 89% | 2749 fps | 100% |
| Shooters World SW4350 | <<locked>> | 98% | 55,608 psi | 89% | 2789 fps | 98.5% |
| SNPE Vectan SP 11 | <<locked>> | 92% | 54,665 psi | 88% | 2805 fps | 100% |
| SNPE Vectan SP 7 | <<locked>> | 86% | 56,260 psi | 90% | 2769 fps | 99.6% |
| SNPE Vectan SP 9 | <<locked>> | 86% | 53,417 psi | 86% | 2740 fps | 100% |
| SNPE Vectan Tubal 3000 | <<locked>> | 86% | 55,245 psi | 89% | 2651 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 92% | 55,434 psi | 89% | 2651 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 96% | 55,056 psi | 88% | 2710 fps | 98.1% |
| Somchem S321 | <<locked>> | 82% | 55,347 psi | 89% | 2749 fps | 100% |
| Somchem S335 | <<locked>> | 86% | 54,882 psi | 88% | 2654 fps | 100% |
| Somchem S341 | <<locked>> | 86% | 56,115 psi | 90% | 2762 fps | 100% |
| Somchem S355 | <<locked>> | 92% | 53,374 psi | 86% | 2746 fps | 100% |
| Somchem S365ᴾ | <<locked>> | 100% | 51,445 psi | 82% | 2812 fps | 100% |
| Somchem S385ᴾ | <<locked>> | 100% | 47,819 psi | 77% | 2694 fps | 96.3% |
| Vihtavuori N130 | <<locked>> | 82% | 55,201 psi | 89% | 2615 fps | 100% |
| Vihtavuori N133 | <<locked>> | 86% | 55,477 psi | 89% | 2635 fps | 100% |
| Vihtavuori N135 | <<locked>> | 88% | 54,331 psi | 87% | 2680 fps | 100% |
| Vihtavuori N140 | <<locked>> | 88% | 54,766 psi | 88% | 2690 fps | 100% |
| Vihtavuori N150 | <<locked>> | 94% | 55,056 psi | 88% | 2726 fps | 100% |
| Vihtavuori N160 | <<locked>> | 98% | 56,260 psi | 90% | 2808 fps | 99.8% |
| Vihtavuori N530 | <<locked>> | 84% | 54,520 psi | 87% | 2717 fps | 100% |
| Vihtavuori N540 | <<locked>> | 88% | 53,069 psi | 85% | 2694 fps | 100% |
| Vihtavuori N550 | <<locked>> | 98% | 55,056 psi | 88% | 2812 fps | 99.7% |
| Vihtavuori N555ᴾ | <<locked>> | 100% | 43,888 psi | 70% | 2700 fps | 99.1% |
| Winchester 6.5 StaBALL | <<locked>> | 98% | 56,217 psi | 90% | 2782 fps | 100% |
| Winchester 748 | <<locked>> | 84% | 54,360 psi | 87% | 2762 fps | 100% |
| Winchester 760 | <<locked>> | 96% | 53,824 psi | 86% | 2822 fps | 98.1% |
| Winchester StaBALL HDᴾ | <<locked>> | 100% | 35,781 psi | 57% | 2631 fps | 99.2% |
| Winchester StaBALL Match | <<locked>> | 86% | 53,185 psi | 85% | 2746 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% | 49,487 psi | 79% | 2575 fps | 100% |
| Accurate 2495 | <<locked>> | 80% | 42,351 psi | 68% | 2510 fps | 100% |
| Accurate 2520 | <<locked>> | 80% | 49,501 psi | 79% | 2657 fps | 100% |
| Accurate 2700 | <<locked>> | 82% | 44,295 psi | 71% | 2533 fps | 95% |
| Accurate 3100 | <<locked>> | 98% | 39,102 psi | 63% | 2543 fps | 95.7% |
| Accurate 4064 | <<locked>> | 80% | 40,045 psi | 64% | 2507 fps | 100% |
| Accurate 4350 | <<locked>> | 84% | 33,663 psi | 54% | 2441 fps | 95.8% |
| ADI AR 2206H | <<locked>> | 80% | 45,818 psi | 73% | 2618 fps | 99.5% |
| ADI AR 2208 | <<locked>> | 80% | 38,798 psi | 62% | 2470 fps | 97.9% |
| ADI Benchmark 8208 | <<locked>> | 80% | 47,921 psi | 77% | 2625 fps | 100% |
| Alliant AR-Comp | <<locked>> | 80% | 48,240 psi | 77% | 2602 fps | 100% |
| Alliant Power Pro 2000-MR | <<locked>> | 80% | 41,437 psi | 66% | 2648 fps | 98.5% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 38,624 psi | 62% | 2497 fps | 99.1% |
| Alliant Reloder-15 | <<locked>> | 80% | 41,524 psi | 67% | 2559 fps | 98.6% |
| Alliant Reloder-16 | <<locked>> | 82% | 31,937 psi | 51% | 2402 fps | 95% |
| Alliant Reloder-17 | 36.9 gr | 80% | 33,359 psi | 53% | 2470 fps | 97.6% |
| Alliant Reloder-23 | <<locked>> | 90% | 29,414 psi | 47% | 2362 fps | 95.7% |
| Alliant Reloder-26 | <<locked>> | 92% | 33,852 psi | 54% | 2536 fps | 95% |
| Baschieri & Pellagri 107 | <<locked>> | 80% | 44,817 psi | 72% | 2621 fps | 98.8% |
| Bofors RP3 | <<locked>> | 80% | 38,159 psi | 61% | 2497 fps | 99.1% |
| Bofors RP7 | <<locked>> | 88% | 44,556 psi | 71% | 2575 fps | 95.4% |
| Hodgdon Benchmark | <<locked>> | 80% | 49,342 psi | 79% | 2605 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 80% | 46,543 psi | 75% | 2644 fps | 100% |
| Hodgdon CFE223 | <<locked>> | 80% | 51,561 psi | 83% | 2785 fps | 99.8% |
| Hodgdon H380 | <<locked>> | 80% | 39,001 psi | 63% | 2500 fps | 96.9% |
| Hodgdon H414 | 39.7 gr | 88% | 41,350 psi | 66% | 2602 fps | 95.3% |
| Hodgdon H4350 | <<locked>> | 90% | 48,051 psi | 77% | 2677 fps | 95.5% |
| Hodgdon H4895 | <<locked>> | 80% | 46,267 psi | 74% | 2631 fps | 99.8% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 27,485 psi | 44% | 2254 fps | 95% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 42,105 psi | 68% | 2602 fps | 99.6% |
| Hodgdon Superformance | <<locked>> | 90% | 43,700 psi | 70% | 2671 fps | 95.3% |
| Hodgdon TrailBoss | <<locked>> | 80% | 26,397 psi | 42% | 1493 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 44,092 psi | 71% | 2579 fps | 99.6% |
| IMR 3031 | <<locked>> | 80% | 46,021 psi | 74% | 2618 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 40,727 psi | 65% | 2503 fps | 98.5% |
| IMR 4166 Enduron | <<locked>> | 80% | 43,265 psi | 69% | 2523 fps | 95.7% |
| IMR 4350 | <<locked>> | 92% | 44,498 psi | 71% | 2598 fps | 95.4% |
| IMR 4451 Enduron | <<locked>> | 86% | 43,221 psi | 69% | 2552 fps | 95.6% |
| IMR 4831 | <<locked>> | 84% | 32,750 psi | 53% | 2402 fps | 95.5% |
| IMR 4895 | <<locked>> | 80% | 42,540 psi | 68% | 2589 fps | 99.2% |
| IMR 8208 XBR | <<locked>> | 80% | 47,921 psi | 77% | 2625 fps | 100% |
| Lovex D073.6 | <<locked>> | 80% | 44,904 psi | 72% | 2595 fps | 100% |
| Lovex S060 | <<locked>> | 80% | 45,585 psi | 73% | 2552 fps | 99.5% |
| Lovex S062 | <<locked>> | 80% | 40,756 psi | 65% | 2507 fps | 99.6% |
| Lovex S065 | <<locked>> | 84% | 37,913 psi | 61% | 2454 fps | 95.6% |
| Lovex S070 | <<locked>> | 88% | 40,625 psi | 65% | 2530 fps | 95.2% |
| Norma 201 | <<locked>> | 80% | 44,817 psi | 72% | 2569 fps | 99.9% |
| Norma 202 | <<locked>> | 80% | 45,165 psi | 72% | 2575 fps | 100% |
| Norma 203B | <<locked>> | 80% | 40,886 psi | 66% | 2549 fps | 98.9% |
| Norma 204 | <<locked>> | 96% | 50,792 psi | 81% | 2746 fps | 95.6% |
| Norma URP | <<locked>> | 84% | 33,982 psi | 54% | 2444 fps | 95.8% |
| Ramshot Big Game | <<locked>> | 80% | 40,176 psi | 64% | 2556 fps | 98.7% |
| Ramshot Hunter | <<locked>> | 88% | 37,724 psi | 60% | 2533 fps | 95% |
| Ramshot TAC | <<locked>> | 80% | 47,630 psi | 76% | 2631 fps | 98.2% |
| Ramshot Wild Boar | <<locked>> | 80% | 47,384 psi | 76% | 2651 fps | 99.7% |
| Ramshot X-Terminator | <<locked>> | 80% | 51,387 psi | 82% | 2667 fps | 99.9% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 26,963 psi | 43% | 1535 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 80% | 39,523 psi | 63% | 2487 fps | 95.3% |
| ReloadSwiss RS 52 | <<locked>> | 80% | 43,685 psi | 70% | 2657 fps | 99% |
| ReloadSwiss RS 60 | 36.9 gr | 80% | 35,505 psi | 57% | 2533 fps | 99.8% |
| ReloadSwiss RS 62 | <<locked>> | 84% | 33,489 psi | 54% | 2457 fps | 95.3% |
| ReloadSwiss RS 70 | <<locked>> | 86% | 35,969 psi | 58% | 2520 fps | 95.3% |
| Rottweil R 901 | <<locked>> | 80% | 48,820 psi | 78% | 2605 fps | 100% |
| Rottweil R 902 | <<locked>> | 80% | 42,670 psi | 68% | 2523 fps | 99.7% |
| Rottweil R 903 | <<locked>> | 80% | 36,085 psi | 58% | 2448 fps | 98.5% |
| Rottweil R 907 | <<locked>> | 88% | 44,556 psi | 71% | 2575 fps | 95.4% |
| Shooters World Long Rifle | <<locked>> | 84% | 37,913 psi | 61% | 2454 fps | 95.6% |
| Shooters World Match Rifle | <<locked>> | 80% | 44,904 psi | 72% | 2595 fps | 100% |
| Shooters World Precision | <<locked>> | 80% | 40,756 psi | 65% | 2507 fps | 99.6% |
| Shooters World SW4350 | <<locked>> | 88% | 40,625 psi | 65% | 2530 fps | 95.2% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 36,927 psi | 59% | 2493 fps | 98% |
| SNPE Vectan SP 7 | <<locked>> | 80% | 45,963 psi | 74% | 2608 fps | 98.4% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 44,179 psi | 71% | 2589 fps | 99.3% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 45,934 psi | 74% | 2516 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 38,261 psi | 61% | 2388 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 88% | 42,250 psi | 68% | 2500 fps | 95.5% |
| Somchem S321 | <<locked>> | 80% | 51,605 psi | 83% | 2697 fps | 100% |
| Somchem S335 | <<locked>> | 80% | 45,701 psi | 73% | 2523 fps | 100% |
| Somchem S341 | <<locked>> | 80% | 45,614 psi | 73% | 2602 fps | 99.5% |
| Somchem S355 | <<locked>> | 80% | 36,840 psi | 59% | 2451 fps | 98.4% |
| Somchem S365 | <<locked>> | 80% | 26,847 psi | 43% | 2290 fps | 96.3% |
| Somchem S385 | <<locked>> | 98% | 44,744 psi | 72% | 2641 fps | 95.5% |
| Vihtavuori N130 | <<locked>> | 80% | 51,735 psi | 83% | 2569 fps | 100% |
| Vihtavuori N133 | <<locked>> | 80% | 46,267 psi | 74% | 2507 fps | 100% |
| Vihtavuori N135 | <<locked>> | 80% | 42,047 psi | 67% | 2500 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 42,815 psi | 69% | 2513 fps | 100% |
| Vihtavuori N150 | <<locked>> | 80% | 35,099 psi | 56% | 2392 fps | 99.1% |
| Vihtavuori N160 | <<locked>> | 82% | 33,214 psi | 53% | 2392 fps | 95.4% |
| Vihtavuori N530 | <<locked>> | 80% | 47,747 psi | 77% | 2615 fps | 100% |
| Vihtavuori N540 | <<locked>> | 80% | 41,075 psi | 66% | 2503 fps | 100% |
| Vihtavuori N550 | <<locked>> | 84% | 34,940 psi | 56% | 2448 fps | 95.8% |
| Vihtavuori N555 | <<locked>> | 90% | 31,633 psi | 51% | 2438 fps | 95.8% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 30,937 psi | 50% | 2316 fps | 96.8% |
| Winchester 748 | <<locked>> | 80% | 47,688 psi | 76% | 2664 fps | 100% |
| Winchester 760 | <<locked>> | 88% | 41,350 psi | 66% | 2602 fps | 95.3% |
| Winchester StaBALL HD | <<locked>> | 94% | 29,341 psi | 47% | 2438 fps | 96.2% |
| Winchester StaBALL Match | <<locked>> | 80% | 43,816 psi | 70% | 2595 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 97 powders for .260 Ackley Improved loaded with the .264 | 130gr | Swift Scirocco. Alliant Power Pro 2000-MR delivers the highest muzzle velocity at 2,887 fps; across all powders the maximum-charge window runs from 1,677 fps to 2,887 fps. Accurate 3100 gives the best case fill at 100 %, and 97 of the 97 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (430 MPa), the top charges use 57–90 %, leaving at least 10 % headroom. The 130.0 gr projectile in 0.264" calls for a 1:8.5 twist; slower twists will usually not stabilise this weight. Accurate 3100, Alliant Reloder-16, Alliant Reloder-23 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-17, ReloadSwiss RS 60, Hodgdon H414 rank at the top here: for .260 Ackley Improved with the .264 | 130gr | Swift Scirocco 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.