Load Specifications
Load data in caliber 6 x 70 R with .243 | 75gr | Barnes X S bullet and 7 powders. The key underlying parameters are shown in the table above.
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: 25.6"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 2495 | <<locked>> | 82% | 32,314 psi | 86% | 2680 fps | 98.5% |
| Accurate 4064 | <<locked>> | 84% | 32,532 psi | 86% | 2700 fps | 96.2% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 33,939 psi | 90% | 1909 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 34,113 psi | 90% | 1955 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 84% | 32,227 psi | 85% | 2595 fps | 96.7% |
| Vihtavuori N135 | <<locked>> | 84% | 34,026 psi | 90% | 2723 fps | 98.8% |
| Vihtavuori N140 | <<locked>> | 82% | 33,069 psi | 88% | 2664 fps | 96.2% |
Start Load - Barrel Length: 25.6"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 2495 | <<locked>> | 80% | 30,589 psi | 81% | 2635 fps | 98.1% |
| Accurate 4064 | <<locked>> | 82% | 30,487 psi | 81% | 2644 fps | 95.3% |
| Hodgdon TrailBoss | <<locked>> | 80% | 25,309 psi | 67% | 1713 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 25,570 psi | 68% | 1755 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 28,863 psi | 77% | 2503 fps | 95.3% |
| Vihtavuori N135 | <<locked>> | 80% | 30,298 psi | 80% | 2628 fps | 97.8% |
| Vihtavuori N140 | <<locked>> | 80% | 31,328 psi | 83% | 2615 fps | 95.5% |
ᴾ possible press load - work up slowly to this load while watching for signs of excessive pressure.
This overview compares 7 powders for 6 x 70 R loaded with the .243 | 75gr | Barnes X S. Vihtavuori N135 delivers the highest muzzle velocity at 2,723 fps; across all powders the maximum-charge window runs from 1,909 fps to 2,723 fps. Hodgdon TrailBoss gives the best case fill at 100 %, and 7 of the 7 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (260 MPa), the top charges use 85–90 %, leaving at least 10 % headroom. The 75.0 gr projectile in 0.243" calls for a 1:9.5 twist; slower twists will usually not stabilise this weight. 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. Always begin at the start load and work up in small increments while checking case and primer for pressure signs.