Load Specifications
Load data in caliber 8 x 57 IRS with .323 | 139gr | Geco ZERO bullet and 37 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are IMR 3031, Alliant AR-Comp and Accurate 2495.
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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Max Load - Barrel Length: 23.62"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 2015 | <<locked>> | 88% | 40,625 psi | 85% | 2785 fps | 99.5% |
| Accurate 2460 | <<locked>> | 86% | 41,452 psi | 87% | 2822 fps | 97.5% |
| Accurate 2495 | <<locked>> | 96% | 41,002 psi | 86% | 2858 fps | 99.7% |
| Accurate 2520 | <<locked>> | 90% | 41,989 psi | 88% | 2871 fps | 97.3% |
| Accurate 4064 | <<locked>> | 98% | 40,944 psi | 86% | 2877 fps | 98.2% |
| Accurate LT-30 | <<locked>> | 82% | 43,047 psi | 90% | 2753 fps | 99% |
| ADI AR 2219 | <<locked>> | 82% | 41,060 psi | 86% | 2838 fps | 98.5% |
| Alliant AR-Comp | <<locked>> | 92% | 42,946 psi | 90% | 2917 fps | 100% |
| Alliant Reloder-10x | <<locked>> | 84% | 41,002 psi | 86% | 2808 fps | 99.9% |
| Baschieri & Pellagri 106 | <<locked>> | 82% | 41,582 psi | 87% | 2736 fps | 98.9% |
| Hodgdon Benchmark | <<locked>> | 88% | 42,685 psi | 89% | 2799 fps | 96.1% |
| Hodgdon BL-C2 | <<locked>> | 92% | 42,801 psi | 89% | 2904 fps | 96.2% |
| Hodgdon H322 | <<locked>> | 86% | 42,830 psi | 89% | 2874 fps | 98.8% |
| Hodgdon H335 | <<locked>> | 84% | 40,582 psi | 85% | 2828 fps | 97.5% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 32,750 psi | 68% | 1841 fps | 100% |
| IMR 3031 | <<locked>> | 92% | 40,683 psi | 85% | 2894 fps | 99.1% |
| IMR 4198 | <<locked>> | 84% | 42,757 psi | 89% | 2802 fps | 100% |
| Lovex D073.5 | <<locked>> | 86% | 41,365 psi | 86% | 2818 fps | 96.2% |
| Lovex D073.6 | <<locked>> | 94% | 42,917 psi | 90% | 2900 fps | 97.5% |
| Norma 202 | <<locked>> | 92% | 41,423 psi | 87% | 2844 fps | 97.8% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 32,793 psi | 69% | 1883 fps | 100% |
| ReloadSwiss RS 40 | <<locked>> | 86% | 42,554 psi | 89% | 2841 fps | 96.9% |
| ReloadSwiss RS 60ᴾ | <<locked>> | 100% | 42,801 psi | 89% | 2956 fps | 96.4% |
| Rottweil R 901 | <<locked>> | 90% | 42,424 psi | 89% | 2831 fps | 97.7% |
| Shooters World Match Rifle | <<locked>> | 94% | 42,917 psi | 90% | 2900 fps | 97.5% |
| SNPE Vectan SP 10 | <<locked>> | 82% | 41,466 psi | 87% | 2838 fps | 97.6% |
| SNPE Vectan SP 3 | <<locked>> | 84% | 41,814 psi | 87% | 2818 fps | 99.2% |
| SNPE Vectan Tubal 3000 | <<locked>> | 90% | 41,597 psi | 87% | 2756 fps | 97.7% |
| SNPE Vectan Tubal 5000 | <<locked>> | 98% | 43,120 psi | 90% | 2799 fps | 98.9% |
| Somchem S321 | <<locked>> | 88% | 42,975 psi | 90% | 2871 fps | 95.9% |
| Somchem S335 | <<locked>> | 92% | 42,989 psi | 90% | 2805 fps | 98.7% |
| Vihtavuori N130 | <<locked>> | 86% | 41,742 psi | 87% | 2762 fps | 99.9% |
| Vihtavuori N133 | <<locked>> | 90% | 41,278 psi | 86% | 2766 fps | 99.5% |
| Vihtavuori N135 | <<locked>> | 96% | 42,438 psi | 89% | 2874 fps | 99.8% |
| Vihtavuori N140 | <<locked>> | 94% | 41,872 psi | 87% | 2828 fps | 98.2% |
| Vihtavuori N540 | <<locked>> | 96% | 43,221 psi | 90% | 2867 fps | 98% |
| Winchester 748 | <<locked>> | 90% | 41,002 psi | 86% | 2871 fps | 96% |
Recommended = one of the top powders for this cartridge and bullet combination.
Start Load - Barrel Length: 23.62"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 2015 | <<locked>> | 80% | 31,241 psi | 65% | 2569 fps | 97.5% |
| Accurate 2460 | <<locked>> | 80% | 33,605 psi | 70% | 2644 fps | 95.1% |
| Accurate 2495 | 44.8 gr | 82% | 25,193 psi | 53% | 2464 fps | 95.3% |
| Accurate 2520 | <<locked>> | 86% | 36,245 psi | 76% | 2746 fps | 95.6% |
| Accurate 4064 | <<locked>> | 90% | 31,430 psi | 66% | 2654 fps | 95.2% |
| Accurate LT-30 | <<locked>> | 80% | 40,364 psi | 84% | 2700 fps | 98.5% |
| ADI AR 2219 | <<locked>> | 80% | 38,159 psi | 80% | 2776 fps | 97.9% |
| Alliant AR-Comp | 43.2 gr | 80% | 28,718 psi | 60% | 2585 fps | 98.9% |
| Alliant Reloder-10x | <<locked>> | 80% | 36,071 psi | 75% | 2703 fps | 99.4% |
| Baschieri & Pellagri 106 | <<locked>> | 80% | 38,914 psi | 81% | 2684 fps | 98.5% |
| Hodgdon Benchmark | <<locked>> | 86% | 40,147 psi | 84% | 2743 fps | 95.4% |
| Hodgdon BL-C2 | <<locked>> | 90% | 39,871 psi | 83% | 2841 fps | 95.4% |
| Hodgdon H322 | <<locked>> | 80% | 34,809 psi | 73% | 2697 fps | 96.9% |
| Hodgdon H335 | <<locked>> | 80% | 35,215 psi | 74% | 2707 fps | 95.9% |
| Hodgdon TrailBoss | <<locked>> | 80% | 23,989 psi | 50% | 1640 fps | 100% |
| IMR 3031 | 44.2 gr | 82% | 29,240 psi | 61% | 2605 fps | 95.7% |
| IMR 4198 | <<locked>> | 80% | 37,884 psi | 79% | 2700 fps | 99.9% |
| Lovex D073.5 | <<locked>> | 84% | 38,508 psi | 80% | 2756 fps | 95.3% |
| Lovex D073.6 | <<locked>> | 88% | 34,635 psi | 72% | 2720 fps | 95% |
| Norma 202 | <<locked>> | 86% | 34,026 psi | 71% | 2677 fps | 95.6% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 23,946 psi | 50% | 1680 fps | 100% |
| ReloadSwiss RS 40 | <<locked>> | 82% | 37,188 psi | 78% | 2726 fps | 95.4% |
| ReloadSwiss RS 60 | <<locked>> | 98% | 39,972 psi | 84% | 2890 fps | 95.3% |
| Rottweil R 901 | <<locked>> | 84% | 35,447 psi | 74% | 2674 fps | 95.8% |
| Shooters World Match Rifle | <<locked>> | 88% | 34,635 psi | 72% | 2720 fps | 95% |
| SNPE Vectan SP 10 | <<locked>> | 80% | 38,667 psi | 81% | 2779 fps | 96.9% |
| SNPE Vectan SP 3 | <<locked>> | 80% | 36,753 psi | 77% | 2710 fps | 98.3% |
| SNPE Vectan Tubal 3000 | <<locked>> | 84% | 34,301 psi | 72% | 2595 fps | 95.6% |
| SNPE Vectan Tubal 5000 | <<locked>> | 88% | 31,488 psi | 66% | 2546 fps | 95.8% |
| Somchem S321 | <<locked>> | 86% | 40,103 psi | 84% | 2808 fps | 95% |
| Somchem S335 | <<locked>> | 82% | 31,502 psi | 66% | 2546 fps | 95.6% |
| Vihtavuori N130 | <<locked>> | 80% | 34,505 psi | 72% | 2608 fps | 99% |
| Vihtavuori N133 | <<locked>> | 80% | 30,008 psi | 63% | 2507 fps | 96.9% |
| Vihtavuori N135 | <<locked>> | 82% | 26,716 psi | 56% | 2493 fps | 95.8% |
| Vihtavuori N140 | <<locked>> | 86% | 32,227 psi | 67% | 2612 fps | 95.3% |
| Vihtavuori N540 | <<locked>> | 90% | 35,244 psi | 74% | 2697 fps | 95.8% |
| Winchester 748 | <<locked>> | 88% | 38,232 psi | 80% | 2808 fps | 95.1% |
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 74 powders for 8 x 57 IRS loaded with the .323 | 139gr | Geco ZERO. ReloadSwiss RS 60 delivers the highest muzzle velocity at 2,956 fps; across all powders the maximum-charge window runs from 1,841 fps to 2,956 fps. Alliant Reloder-17 gives the best case fill at 100 %, and 74 of the 74 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (330 MPa), the top charges use 68–90 %, leaving at least 10 % headroom. The 139.0 gr projectile in 0.323" calls for a 1:14.5 twist; slower twists will usually not stabilise this weight. Alliant Reloder-17, Hodgdon TrailBoss, ReloadSwiss RS 14 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. IMR 3031, Alliant AR-Comp, Accurate 2495 rank at the top here: for 8 x 57 IRS with the .323 | 139gr | Geco ZERO they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, ADI AR 2206H, ADI AR 2208, Alliant Power Pro 1200-R 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.