Load Specifications
Load data in caliber .357 Auto Mag. with .358 | 125gr | Rim Rock RNFP Cowboy bullet and 38 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Vihtavuori N32C Tin Star, 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 ≥ 60% and propellant combustion ≥ 80%. 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: 6.5"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate Solo 1000² | <<locked>> | 64% | 32,837 psi | 89% | 1457 fps | 100% |
| Accurate Solo 1250² | <<locked>> | 68% | 33,431 psi | 90% | 1529 fps | 100% |
| Accurate TCM*² | <<locked>> | 68% | 29,994 psi | 81% | 1663 fps | 88.8% |
| ADI AP 100 | <<locked>> | 80% | 32,169 psi | 87% | 1660 fps | 99.5% |
| ADI APS 350² | <<locked>> | 64% | 33,228 psi | 90% | 1352 fps | 100% |
| ADI APS 450² | <<locked>> | 64% | 31,995 psi | 87% | 1368 fps | 100% |
| ADI AS 30² | <<locked>> | 64% | 31,937 psi | 86% | 1411 fps | 100% |
| Alliant BE-86² | <<locked>> | 64% | 30,719 psi | 83% | 1470 fps | 100% |
| Alliant BLUE DOT* | <<locked>> | 80% | 31,198 psi | 84% | 1690 fps | 92.4% |
| Alliant Green Dot² | <<locked>> | 64% | 32,735 psi | 89% | 1473 fps | 100% |
| Alliant Herco | <<locked>> | 80% | 33,228 psi | 90% | 1601 fps | 100% |
| Alliant POWER PISTOL² | <<locked>> | 64% | 30,705 psi | 83% | 1677 fps | 98.8% |
| Alliant RED DOT² | <<locked>> | 64% | 31,082 psi | 84% | 1414 fps | 100% |
| Alliant UNIQUE² | <<locked>> | 64% | 30,342 psi | 82% | 1558 fps | 100% |
| Baschieri & Pellagri 100² | <<locked>> | 64% | 32,155 psi | 87% | 1450 fps | 100% |
| Baschieri & Pellagri 102 Pistol | <<locked>> | 80% | 32,474 psi | 88% | 1463 fps | 100% |
| Hodgdon Clays² | <<locked>> | 72% | 32,314 psi | 87% | 1371 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 21,103 psi | 57% | 1214 fps | 100% |
| Maxam CSB 1² | <<locked>> | 68% | 31,212 psi | 84% | 1490 fps | 100% |
| Maxam CSB 2² | <<locked>> | 64% | 31,096 psi | 84% | 1480 fps | 100% |
| Maxam CSB 3² | <<locked>> | 64% | 31,343 psi | 85% | 1463 fps | 100% |
| Maxam CSB 4² | <<locked>> | 64% | 33,127 psi | 90% | 1467 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 19,885 psi | 54% | 1230 fps | 100% |
| ReloadSwiss RS 20² | <<locked>> | 68% | 33,185 psi | 90% | 1591 fps | 100% |
| ReloadSwiss RS 24² | <<locked>> | 68% | 32,184 psi | 87% | 1706 fps | 95.9% |
| Rottweil P 806² | <<locked>> | 68% | 29,486 psi | 80% | 1647 fps | 100% |
| SNPE Vectan A0² | <<locked>> | 68% | 31,488 psi | 85% | 1535 fps | 100% |
| SNPE Vectan BA 9² | <<locked>> | 64% | 33,257 psi | 90% | 1529 fps | 100% |
| SNPE Vectan BA7 1/2² | <<locked>> | 72% | 30,995 psi | 84% | 1594 fps | 100% |
| SNPE Vectan BA9 1/2² | <<locked>> | 64% | 32,953 psi | 89% | 1526 fps | 100% |
| Somchem MS200² | <<locked>> | 64% | 31,357 psi | 85% | 1542 fps | 100% |
| Vihtavuori 3N37² | <<locked>> | 68% | 33,257 psi | 90% | 1647 fps | 100% |
| Vihtavuori 3N38 | <<locked>> | 80% | 33,054 psi | 89% | 1709 fps | 97% |
| Vihtavuori N105 | <<locked>> | 80% | 29,834 psi | 81% | 1693 fps | 98.5% |
| Vihtavuori N32C Tin Star | <<locked>> | 92% | 32,706 psi | 88% | 1381 fps | 100% |
| Vihtavuori N340² | <<locked>> | 64% | 31,038 psi | 84% | 1539 fps | 100% |
| Vihtavuori N350² | <<locked>> | 72% | 32,576 psi | 88% | 1631 fps | 100% |
| Winchester AutoComp ² | <<locked>> | 68% | 32,793 psi | 89% | 1532 fps | 100% |
Recommended = one of the top powders for this cartridge and bullet combination.
Start Load - Barrel Length: 6.5"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate Solo 1000² | <<locked>> | 60% | 29,559 psi | 80% | 1407 fps | 100% |
| Accurate Solo 1250² | <<locked>> | 60% | 26,629 psi | 72% | 1417 fps | 100% |
| Accurate TCM*² | <<locked>> | 64% | 26,005 psi | 70% | 1572 fps | 86% |
| ADI AP 100*² | <<locked>> | 60% | 18,318 psi | 50% | 1335 fps | 93.4% |
| ADI APS 350² | <<locked>> | 60% | 30,327 psi | 82% | 1309 fps | 100% |
| ADI APS 450² | <<locked>> | 60% | 29,341 psi | 79% | 1325 fps | 100% |
| ADI AS 30² | <<locked>> | 60% | 29,196 psi | 79% | 1365 fps | 100% |
| Alliant BE-86² | <<locked>> | 60% | 27,514 psi | 74% | 1414 fps | 100% |
| Alliant BLUE DOT*² | <<locked>> | 68% | 22,046 psi | 60% | 1473 fps | 86% |
| Alliant Green Dot² | <<locked>> | 60% | 29,501 psi | 80% | 1421 fps | 100% |
| Alliant Herco² | <<locked>> | 60% | 20,015 psi | 54% | 1339 fps | 100% |
| Alliant POWER PISTOL² | <<locked>> | 60% | 26,832 psi | 73% | 1591 fps | 97.6% |
| Alliant RED DOT² | <<locked>> | 60% | 28,311 psi | 77% | 1368 fps | 100% |
| Alliant UNIQUE² | <<locked>> | 60% | 27,021 psi | 73% | 1496 fps | 100% |
| Baschieri & Pellagri 100² | <<locked>> | 60% | 28,964 psi | 78% | 1401 fps | 100% |
| Baschieri & Pellagri 102 Pistol² | <<locked>> | 60% | 19,203 psi | 52% | 1227 fps | 100% |
| Hodgdon Clays² | <<locked>> | 60% | 24,758 psi | 67% | 1247 fps | 100% |
| Hodgdon TrailBoss² | 5.4 gr | 60% | 9,732 psi | 26% | 915 fps | 100% |
| Maxam CSB 1² | <<locked>> | 60% | 25,005 psi | 68% | 1381 fps | 100% |
| Maxam CSB 2² | <<locked>> | 60% | 28,050 psi | 76% | 1427 fps | 100% |
| Maxam CSB 3² | <<locked>> | 60% | 28,268 psi | 76% | 1414 fps | 100% |
| Maxam CSB 4² | <<locked>> | 60% | 29,805 psi | 81% | 1417 fps | 100% |
| ReloadSwiss RS 14² | 5.5 gr | 60% | 9,224 psi | 25% | 919 fps | 100% |
| ReloadSwiss RS 20² | <<locked>> | 60% | 26,266 psi | 71% | 1473 fps | 100% |
| ReloadSwiss RS 24*² | <<locked>> | 60% | 24,700 psi | 67% | 1542 fps | 91.9% |
| Rottweil P 806² | <<locked>> | 60% | 22,249 psi | 60% | 1493 fps | 99.1% |
| SNPE Vectan A0² | <<locked>> | 60% | 25,077 psi | 68% | 1421 fps | 100% |
| SNPE Vectan BA 9² | <<locked>> | 60% | 29,414 psi | 80% | 1470 fps | 100% |
| SNPE Vectan BA7 1/2² | <<locked>> | 60% | 21,988 psi | 59% | 1407 fps | 99.3% |
| SNPE Vectan BA9 1/2² | <<locked>> | 60% | 29,399 psi | 79% | 1470 fps | 100% |
| Somchem MS200² | <<locked>> | 60% | 27,992 psi | 76% | 1483 fps | 100% |
| Vihtavuori 3N37² | <<locked>> | 60% | 26,121 psi | 71% | 1516 fps | 100% |
| Vihtavuori 3N38*² | <<locked>> | 60% | 17,637 psi | 48% | 1339 fps | 86.7% |
| Vihtavuori N105*² | <<locked>> | 60% | 15,011 psi | 41% | 1306 fps | 87.5% |
| Vihtavuori N32C Tin Star² | 7.3 gr | 60% | 16,418 psi | 44% | 1089 fps | 100% |
| Vihtavuori N340² | <<locked>> | 60% | 27,586 psi | 75% | 1480 fps | 100% |
| Vihtavuori N350² | <<locked>> | 60% | 22,495 psi | 61% | 1434 fps | 99.8% |
| Winchester AutoComp ² | <<locked>> | 60% | 26,194 psi | 71% | 1424 fps | 100% |
Recommended = one of the top powders for this cartridge and bullet combination.
* not dangerous but load has suboptimal powder burnt with possible characteristics such as extensive muzzle flash or inaccurate loads.
² fill rate low - you might want to consider using a filler to ensure proper ignition.
ᴾ possible press load - work up slowly to this load while watching for signs of excessive pressure.
This overview compares 38 powders for .357 Auto Mag. loaded with the .358 | 125gr | Rim Rock RNFP Cowboy. Vihtavuori 3N38 delivers the highest muzzle velocity at 1,709 fps; across all powders the maximum-charge window runs from 1,214 fps to 1,709 fps. Hodgdon TrailBoss gives the best case fill at 100 %, and 9 of the 38 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (255 MPa), the top charges use 54–90 %, leaving at least 10 % headroom. 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. Vihtavuori N32C Tin Star, ReloadSwiss RS 14, Hodgdon TrailBoss rank at the top here: for .357 Auto Mag. with the .358 | 125gr | Rim Rock RNFP Cowboy they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Accurate TCM, Alliant BLUE DOT burn incompletely and react more sensitively to barrel length and temperature. Hodgdon TrailBoss, ReloadSwiss RS 14, Vihtavuori N32C Tin Star stay subsonic at start load. Always begin at the start load and work up in small increments while checking case and primer for pressure signs.