Load Specifications
Load data in caliber 8.5 mm Messner Mag. with .338 | 300gr | MAKER .338 ARC/Spectre Expanding Subsonic bullet and 77 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Winchester StaBALL HD, Vihtavuori N560 and Accurate MAGPRO.
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 3100 | <<locked>> | 94% | 54,911 psi | 86% | 2451 fps | 100% |
| Accurate 4350 | <<locked>> | 86% | 56,608 psi | 89% | 2467 fps | 100% |
| Accurate MAGPRO | <<locked>> | 94% | 57,043 psi | 89% | 2595 fps | 99.5% |
| ADI AR 2208 | <<locked>> | 82% | 57,406 psi | 90% | 2418 fps | 100% |
| ADI AR 2209 | <<locked>> | 92% | 57,145 psi | 90% | 2530 fps | 100% |
| ADI AR 2213 | <<locked>> | 94% | 54,723 psi | 86% | 2539 fps | 99.8% |
| ADI AR 2217ᴾ | <<locked>> | 100% | 48,907 psi | 77% | 2457 fps | 99.5% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 43,540 psi | 68% | 2431 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 88% | 57,319 psi | 90% | 2513 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 82% | 54,795 psi | 86% | 2480 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 92% | 56,594 psi | 89% | 2520 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 94% | 54,679 psi | 86% | 2536 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 96% | 55,883 psi | 88% | 2497 fps | 100% |
| Alliant Reloder-25ᴾ | <<locked>> | 100% | 54,911 psi | 86% | 2559 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 92% | 56,188 psi | 88% | 2585 fps | 100% |
| Baschieri & Pellagri 109 | <<locked>> | 96% | 56,405 psi | 88% | 2510 fps | 98.2% |
| Bofors RP15 | <<locked>> | 98% | 57,203 psi | 90% | 2569 fps | 100% |
| Bofors RP30ᴾ | <<locked>> | 100% | 51,053 psi | 80% | 2523 fps | 99.8% |
| Bofors RP5 | <<locked>> | 94% | 54,679 psi | 86% | 2536 fps | 100% |
| Bofors RP7 | <<locked>> | 84% | 55,288 psi | 87% | 2421 fps | 100% |
| Hodgdon H1000ᴾ | <<locked>> | 100% | 53,983 psi | 85% | 2530 fps | 100% |
| Hodgdon H414 | <<locked>> | 84% | 54,447 psi | 85% | 2474 fps | 100% |
| Hodgdon H4350 | <<locked>> | 84% | 57,159 psi | 90% | 2480 fps | 100% |
| Hodgdon H4831 | <<locked>> | 92% | 54,795 psi | 86% | 2487 fps | 99.4% |
| Hodgdon H4831 SC | <<locked>> | 94% | 57,290 psi | 90% | 2516 fps | 99.6% |
| Hodgdon Hybrid 100V | <<locked>> | 90% | 57,580 psi | 90% | 2441 fps | 100% |
| Hodgdon Retumboᴾ | <<locked>> | 100% | 53,882 psi | 84% | 2631 fps | 100% |
| Hodgdon Superformance | <<locked>> | 84% | 54,592 psi | 86% | 2510 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,246 psi | 58% | 1493 fps | 100% |
| IMR 4350 | <<locked>> | 88% | 56,797 psi | 89% | 2461 fps | 100% |
| IMR 4451 Enduron | <<locked>> | 84% | 56,797 psi | 89% | 2441 fps | 100% |
| IMR 4831 | <<locked>> | 88% | 56,739 psi | 89% | 2461 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 92% | 55,883 psi | 88% | 2467 fps | 99.6% |
| IMR 7828 SSC | <<locked>> | 96% | 56,231 psi | 88% | 2572 fps | 99.9% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 39,131 psi | 61% | 2352 fps | 97.9% |
| Lovex S065 | <<locked>> | 86% | 57,406 psi | 90% | 2438 fps | 100% |
| Lovex S070 | <<locked>> | 86% | 55,492 psi | 87% | 2438 fps | 100% |
| Lovex S071ᴾ | <<locked>> | 100% | 55,854 psi | 88% | 2461 fps | 100% |
| Norma 204 | <<locked>> | 86% | 54,056 psi | 85% | 2467 fps | 99.9% |
| Norma 217ᴾ | <<locked>> | 100% | 39,305 psi | 62% | 2379 fps | 99.6% |
| Norma MRP | <<locked>> | 92% | 54,476 psi | 85% | 2552 fps | 100% |
| Norma URP | <<locked>> | 86% | 54,897 psi | 86% | 2454 fps | 100% |
| Ramshot Grand | <<locked>> | 96% | 56,913 psi | 89% | 2589 fps | 100% |
| Ramshot Hunter | <<locked>> | 88% | 57,305 psi | 90% | 2510 fps | 100% |
| Ramshot Magnum | <<locked>> | 98% | 54,998 psi | 86% | 2530 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,058 psi | 60% | 1529 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 86% | 56,492 psi | 89% | 2493 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 86% | 54,679 psi | 86% | 2520 fps | 100% |
| ReloadSwiss RS 76ᴾ | <<locked>> | 100% | 54,331 psi | 85% | 2628 fps | 100% |
| ReloadSwiss RS 80ᴾ | <<locked>> | 100% | 49,182 psi | 77% | 2539 fps | 98.9% |
| Rottweil R 903 | <<locked>> | 82% | 56,855 psi | 89% | 2415 fps | 100% |
| Rottweil R 904 | <<locked>> | 90% | 54,882 psi | 86% | 2454 fps | 99.7% |
| Rottweil R 905 | <<locked>> | 92% | 56,057 psi | 88% | 2510 fps | 100% |
| Rottweil R 907 | <<locked>> | 84% | 55,288 psi | 87% | 2421 fps | 100% |
| Shooters World Long Rifle | <<locked>> | 86% | 57,406 psi | 90% | 2438 fps | 100% |
| Shooters World SW4350 | <<locked>> | 86% | 55,492 psi | 87% | 2438 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 82% | 56,521 psi | 89% | 2290 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 86% | 56,521 psi | 89% | 2402 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 92% | 55,622 psi | 87% | 2507 fps | 100% |
| Somchem S355 | <<locked>> | 82% | 56,275 psi | 88% | 2405 fps | 100% |
| Somchem S361 | <<locked>> | 90% | 56,115 psi | 88% | 2451 fps | 99.5% |
| Somchem S365 | <<locked>> | 88% | 55,317 psi | 87% | 2454 fps | 100% |
| Somchem S385 | <<locked>> | 92% | 56,608 psi | 89% | 2484 fps | 100% |
| Vihtavuori N150 | <<locked>> | 84% | 57,421 psi | 90% | 2379 fps | 100% |
| Vihtavuori N160 | <<locked>> | 86% | 56,753 psi | 89% | 2444 fps | 100% |
| Vihtavuori N165 | <<locked>> | 96% | 56,043 psi | 88% | 2467 fps | 100% |
| Vihtavuori N170ᴾ | <<locked>> | 100% | 54,375 psi | 85% | 2484 fps | 96.2% |
| Vihtavuori N550 | <<locked>> | 86% | 55,825 psi | 87% | 2454 fps | 100% |
| Vihtavuori N555 | <<locked>> | 92% | 54,694 psi | 86% | 2477 fps | 100% |
| Vihtavuori N560 | <<locked>> | 92% | 54,375 psi | 85% | 2556 fps | 99.6% |
| Vihtavuori N565 | <<locked>> | 98% | 53,925 psi | 85% | 2539 fps | 99.6% |
| Vihtavuori N568ᴾ | <<locked>> | 100% | 50,488 psi | 79% | 2543 fps | 98.6% |
| Vihtavuori N570ᴾ | <<locked>> | 100% | 47,834 psi | 75% | 2536 fps | 96.4% |
| Winchester 6.5 StaBALL | <<locked>> | 86% | 55,898 psi | 88% | 2408 fps | 100% |
| Winchester 760 | <<locked>> | 84% | 54,679 psi | 86% | 2474 fps | 100% |
| Winchester StaBALL HD | <<locked>> | 98% | 57,232 psi | 90% | 2621 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 94% | 56,376 psi | 88% | 2484 fps | 100% |
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 |
|---|---|---|---|---|---|---|
| Accurate 3100 | <<locked>> | 80% | 34,635 psi | 54% | 2139 fps | 99.2% |
| Accurate 4350 | <<locked>> | 80% | 46,369 psi | 73% | 2336 fps | 100% |
| Accurate MAGPRO | 68.1 gr | 80% | 35,143 psi | 55% | 2231 fps | 95% |
| ADI AR 2208 | <<locked>> | 80% | 54,143 psi | 85% | 2379 fps | 100% |
| ADI AR 2209 | <<locked>> | 80% | 38,551 psi | 60% | 2241 fps | 98.3% |
| ADI AR 2213 | <<locked>> | 80% | 34,476 psi | 54% | 2188 fps | 95.7% |
| ADI AR 2217 | <<locked>> | 88% | 33,156 psi | 52% | 2162 fps | 95.4% |
| ADI AR 2225 | <<locked>> | 84% | 26,339 psi | 41% | 2037 fps | 95.4% |
| Alliant Reloder-16 | <<locked>> | 80% | 44,382 psi | 70% | 2339 fps | 100% |
| Alliant Reloder-17 | <<locked>> | 80% | 51,082 psi | 80% | 2434 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 80% | 38,667 psi | 61% | 2241 fps | 98.3% |
| Alliant Reloder-22 | <<locked>> | 80% | 34,476 psi | 54% | 2198 fps | 97.4% |
| Alliant Reloder-23 | <<locked>> | 80% | 33,243 psi | 52% | 2159 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 28,906 psi | 45% | 2096 fps | 98.5% |
| Alliant Reloder-26 | <<locked>> | 80% | 36,172 psi | 57% | 2287 fps | 100% |
| Baschieri & Pellagri 109 | <<locked>> | 88% | 44,179 psi | 69% | 2316 fps | 95.5% |
| Bofors RP15 | <<locked>> | 80% | 32,169 psi | 50% | 2146 fps | 96.4% |
| Bofors RP30 | <<locked>> | 86% | 32,111 psi | 50% | 2182 fps | 95.8% |
| Bofors RP5 | <<locked>> | 80% | 34,476 psi | 54% | 2198 fps | 97.4% |
| Bofors RP7 | <<locked>> | 80% | 48,950 psi | 77% | 2333 fps | 99.9% |
| Hodgdon H1000 | <<locked>> | 84% | 31,647 psi | 50% | 2129 fps | 95.5% |
| Hodgdon H414 | <<locked>> | 80% | 47,776 psi | 75% | 2379 fps | 100% |
| Hodgdon H4350 | <<locked>> | 80% | 50,473 psi | 79% | 2388 fps | 99.9% |
| Hodgdon H4831 | <<locked>> | 80% | 36,709 psi | 58% | 2192 fps | 95.9% |
| Hodgdon H4831 SC | <<locked>> | 80% | 36,114 psi | 57% | 2178 fps | 95.7% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 41,945 psi | 66% | 2238 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 80% | 28,224 psi | 44% | 2113 fps | 95.1% |
| Hodgdon Superformance | <<locked>> | 80% | 47,166 psi | 74% | 2408 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 27,920 psi | 44% | 1329 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 44,324 psi | 69% | 2283 fps | 99.7% |
| IMR 4451 Enduron | <<locked>> | 80% | 50,256 psi | 79% | 2352 fps | 100% |
| IMR 4831 | <<locked>> | 80% | 43,932 psi | 69% | 2287 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 38,493 psi | 60% | 2188 fps | 96.6% |
| IMR 7828 SSC | <<locked>> | 80% | 33,069 psi | 52% | 2169 fps | 95.3% |
| IMR 8133 Enduron | <<locked>> | 94% | 32,329 psi | 51% | 2205 fps | 95.5% |
| Lovex S065 | <<locked>> | 80% | 47,906 psi | 75% | 2310 fps | 100% |
| Lovex S070 | <<locked>> | 80% | 46,209 psi | 72% | 2310 fps | 100% |
| Lovex S071 | <<locked>> | 80% | 29,907 psi | 47% | 2037 fps | 98.1% |
| Norma 204 | <<locked>> | 80% | 44,396 psi | 70% | 2323 fps | 99.2% |
| Norma 217 | <<locked>> | 88% | 26,716 psi | 42% | 2080 fps | 95.2% |
| Norma MRP | <<locked>> | 80% | 35,839 psi | 56% | 2254 fps | 98.9% |
| Norma URP | <<locked>> | 80% | 45,426 psi | 71% | 2323 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 32,518 psi | 51% | 2169 fps | 95.5% |
| Ramshot Hunter | <<locked>> | 80% | 44,193 psi | 69% | 2329 fps | 100% |
| Ramshot Magnum | <<locked>> | 80% | 28,892 psi | 45% | 2073 fps | 96% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 28,558 psi | 45% | 1362 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 46,064 psi | 72% | 2356 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 44,150 psi | 69% | 2375 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 27,050 psi | 42% | 2087 fps | 95.7% |
| ReloadSwiss RS 80 | <<locked>> | 92% | 36,724 psi | 58% | 2316 fps | 95.7% |
| Rottweil R 903 | <<locked>> | 80% | 53,359 psi | 84% | 2372 fps | 100% |
| Rottweil R 904 | <<locked>> | 80% | 40,030 psi | 63% | 2224 fps | 97.6% |
| Rottweil R 905 | <<locked>> | 80% | 37,985 psi | 60% | 2228 fps | 98.3% |
| Rottweil R 907 | <<locked>> | 80% | 48,950 psi | 77% | 2333 fps | 99.9% |
| Shooters World Long Rifle | <<locked>> | 80% | 47,906 psi | 75% | 2310 fps | 100% |
| Shooters World SW4350 | <<locked>> | 80% | 46,209 psi | 72% | 2310 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 53,258 psi | 83% | 2254 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 46,746 psi | 73% | 2270 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 37,666 psi | 59% | 2224 fps | 98.2% |
| Somchem S355 | <<locked>> | 80% | 53,084 psi | 83% | 2365 fps | 100% |
| Somchem S361 | <<locked>> | 80% | 40,422 psi | 63% | 2215 fps | 96.9% |
| Somchem S365 | <<locked>> | 80% | 42,380 psi | 66% | 2283 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 38,566 psi | 60% | 2211 fps | 99% |
| Vihtavuori N150 | <<locked>> | 80% | 50,792 psi | 80% | 2300 fps | 100% |
| Vihtavuori N160 | <<locked>> | 80% | 46,847 psi | 73% | 2316 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 33,417 psi | 52% | 2110 fps | 97.4% |
| Vihtavuori N170 | <<locked>> | 98% | 50,836 psi | 80% | 2431 fps | 95.5% |
| Vihtavuori N550 | <<locked>> | 80% | 46,151 psi | 72% | 2323 fps | 100% |
| Vihtavuori N555 | <<locked>> | 80% | 37,275 psi | 58% | 2221 fps | 100% |
| Vihtavuori N560 | 66.8 gr | 80% | 36,085 psi | 57% | 2244 fps | 96% |
| Vihtavuori N565 | <<locked>> | 84% | 33,866 psi | 53% | 2195 fps | 95.5% |
| Vihtavuori N568 | <<locked>> | 92% | 38,406 psi | 60% | 2333 fps | 95.7% |
| Vihtavuori N570 | <<locked>> | 98% | 44,614 psi | 70% | 2480 fps | 95.5% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 45,600 psi | 71% | 2280 fps | 100% |
| Winchester 760 | <<locked>> | 80% | 47,950 psi | 75% | 2382 fps | 100% |
| Winchester StaBALL HD | 66.2 gr | 80% | 29,515 psi | 46% | 2195 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 35,056 psi | 55% | 2149 fps | 97.4% |
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 77 powders for 8.5 mm Messner Mag. loaded with the .338 | 300gr | MAKER .338 ARC/Spectre Expanding Subsonic. Hodgdon Retumbo delivers the highest muzzle velocity at 2,631 fps; across all powders the maximum-charge window runs from 1,493 fps to 2,631 fps. ADI AR 2217 gives the best case fill at 100 %, and 77 of the 77 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (440 MPa), the top charges use 58–90 %, leaving at least 10 % headroom. The 300.0 gr projectile in 0.338" calls for a 1:11.5 twist; slower twists will usually not stabilise this weight. ADI AR 2217, ADI AR 2225, Alliant Reloder-25 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. Winchester StaBALL HD, Vihtavuori N560, Accurate MAGPRO rank at the top here: for 8.5 mm Messner Mag. with the .338 | 300gr | MAKER .338 ARC/Spectre Expanding Subsonic 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.