Load Specifications
Load data in caliber 6 x 70 R with .243 | 105gr | Berger BT bullet and 9 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Somchem S365, ReloadSwiss RS 14 and Hodgdon TrailBoss.
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 |
|---|---|---|---|---|---|---|
| Alliant Reloder- TS 15.5 | <<locked>> | 82% | 33,402 psi | 89% | 2349 fps | 96.7% |
| Bofors RP3 | <<locked>> | 82% | 32,764 psi | 87% | 2346 fps | 96.6% |
| Hodgdon TrailBoss | <<locked>> | 98% | 33,881 psi | 90% | 1601 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 98% | 33,750 psi | 90% | 1631 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 84% | 33,315 psi | 88% | 2428 fps | 98.3% |
| Rottweil R 903 | <<locked>> | 84% | 33,040 psi | 88% | 2346 fps | 96.4% |
| Somchem S355 | <<locked>> | 84% | 34,098 psi | 90% | 2356 fps | 96.4% |
| Somchem S365 | <<locked>> | 94% | 33,562 psi | 89% | 2431 fps | 97.6% |
| Vihtavuori N150 | <<locked>> | 84% | 32,489 psi | 86% | 2300 fps | 97.4% |
Recommended = one of the top powders for this cartridge and bullet combination.
Start Load - Barrel Length: 25.6"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 31,314 psi | 83% | 2300 fps | 95.9% |
| Bofors RP3 | <<locked>> | 80% | 30,719 psi | 81% | 2300 fps | 95.8% |
| Hodgdon TrailBoss | 8.4 gr | 80% | 25,817 psi | 68% | 1444 fps | 100% |
| ReloadSwiss RS 14 | 8.5 gr | 80% | 25,773 psi | 68% | 1473 fps | 100% |
| ReloadSwiss RS 60 | <<locked>> | 80% | 29,254 psi | 78% | 2316 fps | 96.5% |
| Rottweil R 903 | <<locked>> | 82% | 30,951 psi | 82% | 2297 fps | 95.6% |
| Somchem S355 | <<locked>> | 82% | 32,039 psi | 85% | 2306 fps | 95.7% |
| Somchem S365 | 27.2 gr | 88% | 27,949 psi | 74% | 2280 fps | 95% |
| Vihtavuori N150 | <<locked>> | 80% | 28,558 psi | 76% | 2205 fps | 95.9% |
Recommended = one of the top powders for this cartridge and bullet combination.
This overview compares 9 powders for 6 x 70 R loaded with the .243 | 105gr | Berger BT. Somchem S365 delivers the highest muzzle velocity at 2,431 fps; across all powders the maximum-charge window runs from 1,601 fps to 2,431 fps. Hodgdon TrailBoss gives the best case fill at 98 %, and 9 of the 9 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (260 MPa), the top charges use 86–90 %, leaving at least 10 % headroom. The 105.0 gr projectile in 0.243" calls for a 1:9.0 twist; slower twists will usually not stabilise this weight. Somchem S365, ReloadSwiss RS 14, Hodgdon TrailBoss rank at the top here: for 6 x 70 R with the .243 | 105gr | Berger BT 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.