Load Specifications
Bullet Manufacturer:Sierra
Bullet Weight:250 gr
Bullet Diameter:0.338"
Bullet Length:<<locked>>
Caliber:.338 RCM load data
Case Length (l3):2"
Cartridge Length (C.O.L.):<<locked>>
Case Capacity:71 Grains of Water
Primer Size:Large Rifle (LR)
Barrel Length:24"
Max. allowed Pressure:62,366 psi
Recommended Twist Rate:1:14.0
Load data in caliber .338 RCM with .338 | 250gr | Sierra GameKing bullet and 106 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Alliant Power Pro 2000-MR, ReloadSwiss RS 52 and ReloadSwiss RS 60.
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.
A valid access license is required to use the Personalized Load Calculator.
You can find more information in our FAQ: How can I use the Personalized Load Calculator?
Max Load - Barrel Length: 24"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 2015 | <<locked>> | 88% | 54,317 psi | 87% | 2303 fps | 100% |
| Accurate 2460 | <<locked>> | 86% | 56,014 psi | 90% | 2369 fps | 100% |
| Accurate 2495 | <<locked>> | 94% | 54,940 psi | 88% | 2359 fps | 100% |
| Accurate 2520 | <<locked>> | 88% | 53,896 psi | 86% | 2379 fps | 100% |
| Accurate 2700 | <<locked>> | 94% | 55,448 psi | 89% | 2356 fps | 96.6% |
| Accurate 4064 | <<locked>> | 96% | 54,462 psi | 87% | 2398 fps | 100% |
| Accurate 4350ᴾ | <<locked>> | 100% | 46,325 psi | 74% | 2369 fps | 98.6% |
| Accurate LT-30 | <<locked>> | 82% | 53,896 psi | 86% | 2254 fps | 100% |
| Accurate LT-32 | <<locked>> | 82% | 54,302 psi | 87% | 2274 fps | 100% |
| ADI AR 2206H | <<locked>> | 92% | 56,420 psi | 90% | 2431 fps | 100% |
| ADI AR 2208 | <<locked>> | 96% | 53,795 psi | 86% | 2382 fps | 99.6% |
| ADI AR 2219 | <<locked>> | 82% | 54,317 psi | 87% | 2359 fps | 100% |
| ADI Benchmark 8208 | <<locked>> | 90% | 55,579 psi | 89% | 2388 fps | 100% |
| Alliant AR-Comp | <<locked>> | 90% | 55,724 psi | 89% | 2365 fps | 100% |
| Alliant Power Pro 1200-R | <<locked>> | 84% | 54,056 psi | 87% | 2438 fps | 100% |
| Alliant Power Pro 2000-MR | <<locked>> | 94% | 55,709 psi | 89% | 2533 fps | 99.8% |
| Alliant Reloder- TS 15.5 | <<locked>> | 98% | 56,347 psi | 90% | 2441 fps | 100% |
| Alliant Reloder-10x | <<locked>> | 84% | 54,302 psi | 87% | 2306 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 94% | 54,085 psi | 87% | 2421 fps | 99.7% |
| Alliant Reloder-16ᴾ | <<locked>> | 100% | 46,427 psi | 74% | 2375 fps | 98.7% |
| Alliant Reloder-17ᴾ | <<locked>> | 100% | 53,316 psi | 85% | 2503 fps | 100% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 32,721 psi | 52% | 2149 fps | 96.5% |
| Baschieri & Pellagri 106 | <<locked>> | 84% | 56,086 psi | 90% | 2293 fps | 100% |
| Baschieri & Pellagri 107 | <<locked>> | 92% | 56,057 psi | 90% | 2448 fps | 99.6% |
| Bofors RP3 | <<locked>> | 96% | 53,432 psi | 86% | 2418 fps | 100% |
| Bofors RP7ᴾ | <<locked>> | 100% | 54,433 psi | 87% | 2385 fps | 96.8% |
| Hodgdon Benchmark | <<locked>> | 88% | 54,679 psi | 88% | 2336 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 90% | 54,244 psi | 87% | 2418 fps | 100% |
| Hodgdon CFE223 | <<locked>> | 88% | 56,420 psi | 90% | 2503 fps | 99.9% |
| Hodgdon H322 | <<locked>> | 84% | 53,011 psi | 85% | 2343 fps | 100% |
| Hodgdon H335 | <<locked>> | 84% | 53,983 psi | 87% | 2369 fps | 100% |
| Hodgdon H380 | <<locked>> | 96% | 54,839 psi | 88% | 2425 fps | 99.2% |
| Hodgdon H414ᴾ | <<locked>> | 100% | 49,980 psi | 80% | 2415 fps | 96.8% |
| Hodgdon H4350ᴾ | <<locked>> | 100% | 54,940 psi | 88% | 2428 fps | 96.2% |
| Hodgdon H4895 | <<locked>> | 90% | 53,374 psi | 86% | 2395 fps | 100% |
| Hodgdon Hybrid 100Vᴾ | <<locked>> | 100% | 42,424 psi | 68% | 2277 fps | 99.1% |
| Hodgdon LEVERevolution | <<locked>> | 94% | 55,535 psi | 89% | 2467 fps | 100% |
| Hodgdon Superformanceᴾ | <<locked>> | 100% | 51,300 psi | 82% | 2444 fps | 96.2% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 34,751 psi | 56% | 1404 fps | 100% |
| Hodgdon VARGET | <<locked>> | 92% | 54,737 psi | 88% | 2398 fps | 100% |
| IMR 3031 | <<locked>> | 92% | 56,391 psi | 90% | 2421 fps | 100% |
| IMR 4064 | <<locked>> | 94% | 53,461 psi | 86% | 2369 fps | 99.7% |
| IMR 4166 Enduron | <<locked>> | 92% | 54,186 psi | 87% | 2352 fps | 97.3% |
| IMR 4198 | <<locked>> | 84% | 54,607 psi | 88% | 2270 fps | 100% |
| IMR 4451 Enduronᴾ | <<locked>> | 100% | 56,405 psi | 90% | 2411 fps | 97.6% |
| IMR 4831ᴾ | <<locked>> | 100% | 44,411 psi | 71% | 2323 fps | 98.3% |
| IMR 4895 | <<locked>> | 94% | 55,477 psi | 89% | 2451 fps | 100% |
| IMR 8208 XBR | <<locked>> | 90% | 55,579 psi | 89% | 2388 fps | 100% |
| Lovex D073.5 | <<locked>> | 86% | 55,825 psi | 90% | 2379 fps | 100% |
| Lovex D073.6 | <<locked>> | 92% | 55,593 psi | 89% | 2411 fps | 100% |
| Lovex S060 | <<locked>> | 90% | 53,200 psi | 85% | 2326 fps | 99.8% |
| Lovex S062 | <<locked>> | 96% | 56,043 psi | 90% | 2405 fps | 100% |
| Lovex S065ᴾ | <<locked>> | 100% | 51,822 psi | 83% | 2362 fps | 98.2% |
| Lovex S070ᴾ | <<locked>> | 100% | 49,240 psi | 79% | 2346 fps | 96.7% |
| Norma 201 | <<locked>> | 92% | 54,998 psi | 88% | 2382 fps | 100% |
| Norma 202 | <<locked>> | 92% | 55,492 psi | 89% | 2385 fps | 100% |
| Norma 203B | <<locked>> | 94% | 53,229 psi | 85% | 2411 fps | 99.9% |
| Norma URPᴾ | <<locked>> | 100% | 46,514 psi | 75% | 2365 fps | 98.5% |
| Ramshot Big Game | <<locked>> | 94% | 53,301 psi | 85% | 2434 fps | 99.8% |
| Ramshot Hunterᴾ | <<locked>> | 100% | 45,876 psi | 74% | 2359 fps | 96.7% |
| Ramshot TAC | <<locked>> | 90% | 56,318 psi | 90% | 2411 fps | 98.9% |
| Ramshot Wild Boar | <<locked>> | 90% | 55,288 psi | 89% | 2425 fps | 99.9% |
| Ramshot X-Terminator | <<locked>> | 86% | 53,548 psi | 86% | 2352 fps | 99.8% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 35,244 psi | 57% | 1440 fps | 100% |
| ReloadSwiss RS 40 | <<locked>> | 86% | 55,463 psi | 89% | 2375 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 96% | 55,695 psi | 89% | 2411 fps | 98.1% |
| ReloadSwiss RS 52 | <<locked>> | 92% | 53,853 psi | 86% | 2477 fps | 99.8% |
| ReloadSwiss RS 60 | <<locked>> | 98% | 53,301 psi | 85% | 2507 fps | 100% |
| ReloadSwiss RS 62ᴾ | <<locked>> | 100% | 46,166 psi | 74% | 2388 fps | 98.3% |
| ReloadSwiss RS 70ᴾ | <<locked>> | 100% | 47,268 psi | 76% | 2408 fps | 97.8% |
| Rottweil R 901 | <<locked>> | 90% | 56,420 psi | 90% | 2365 fps | 100% |
| Rottweil R 902 | <<locked>> | 94% | 55,535 psi | 89% | 2379 fps | 100% |
| Rottweil R 903 | <<locked>> | 98% | 53,040 psi | 85% | 2405 fps | 100% |
| Rottweil R 907ᴾ | <<locked>> | 100% | 54,433 psi | 87% | 2385 fps | 96.8% |
| Shooters World Long Rifleᴾ | <<locked>> | 100% | 51,822 psi | 83% | 2362 fps | 98.2% |
| Shooters World Match Rifle | <<locked>> | 92% | 55,593 psi | 89% | 2411 fps | 100% |
| Shooters World Precision | <<locked>> | 96% | 56,043 psi | 90% | 2405 fps | 100% |
| Shooters World SW4350ᴾ | <<locked>> | 100% | 49,240 psi | 79% | 2346 fps | 96.7% |
| Shooters World Tactical Rifle | <<locked>> | 84% | 55,506 psi | 89% | 2352 fps | 100% |
| SNPE Vectan SP 10 | <<locked>> | 82% | 54,752 psi | 88% | 2372 fps | 100% |
| SNPE Vectan SP 11 | <<locked>> | 98% | 54,998 psi | 88% | 2461 fps | 99.9% |
| SNPE Vectan SP 3 | <<locked>> | 84% | 54,897 psi | 88% | 2320 fps | 100% |
| SNPE Vectan SP 7 | <<locked>> | 90% | 54,172 psi | 87% | 2385 fps | 99% |
| SNPE Vectan SP 9 | <<locked>> | 92% | 54,752 psi | 88% | 2408 fps | 99.9% |
| SNPE Vectan Tubal 3000 | <<locked>> | 90% | 54,186 psi | 87% | 2293 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 96% | 53,650 psi | 86% | 2290 fps | 100% |
| SNPE Vectan Tubal 7000ᴾ | <<locked>> | 100% | 52,388 psi | 84% | 2326 fps | 96.9% |
| Somchem S321 | <<locked>> | 86% | 53,417 psi | 86% | 2382 fps | 100% |
| Somchem S335 | <<locked>> | 92% | 56,101 psi | 90% | 2329 fps | 100% |
| Somchem S341 | <<locked>> | 90% | 53,751 psi | 86% | 2382 fps | 99.8% |
| Somchem S355 | <<locked>> | 98% | 53,563 psi | 86% | 2402 fps | 100% |
| Somchem S365ᴾ | <<locked>> | 100% | 41,220 psi | 66% | 2320 fps | 99.8% |
| Vihtavuori N130 | <<locked>> | 86% | 53,780 psi | 86% | 2260 fps | 100% |
| Vihtavuori N133 | <<locked>> | 90% | 54,143 psi | 87% | 2280 fps | 100% |
| Vihtavuori N135 | <<locked>> | 94% | 54,752 psi | 88% | 2349 fps | 100% |
| Vihtavuori N140 | <<locked>> | 94% | 55,898 psi | 90% | 2365 fps | 100% |
| Vihtavuori N150ᴾ | <<locked>> | 100% | 55,419 psi | 89% | 2388 fps | 100% |
| Vihtavuori N160ᴾ | <<locked>> | 100% | 48,849 psi | 78% | 2362 fps | 98.7% |
| Vihtavuori N530 | <<locked>> | 88% | 52,866 psi | 85% | 2349 fps | 100% |
| Vihtavuori N540 | <<locked>> | 94% | 53,896 psi | 86% | 2365 fps | 100% |
| Vihtavuori N550ᴾ | <<locked>> | 100% | 47,950 psi | 77% | 2369 fps | 98.5% |
| Vihtavuori N555ᴾ | <<locked>> | 100% | 34,505 psi | 55% | 2211 fps | 96.5% |
| Winchester 6.5 StaBALLᴾ | <<locked>> | 100% | 50,053 psi | 80% | 2352 fps | 99.9% |
| Winchester 748 | <<locked>> | 90% | 55,651 psi | 89% | 2434 fps | 100% |
| Winchester 760ᴾ | <<locked>> | 100% | 50,299 psi | 81% | 2418 fps | 96.8% |
| Winchester StaBALL Match | <<locked>> | 92% | 54,172 psi | 87% | 2415 fps | 100% |
Recommended = one of the top powders for this cartridge and bullet combination.
Start Load - Barrel Length: 24"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 2015 | <<locked>> | 80% | 42,424 psi | 68% | 2152 fps | 100% |
| Accurate 2460 | <<locked>> | 80% | 46,064 psi | 74% | 2244 fps | 100% |
| Accurate 2495 | <<locked>> | 80% | 34,824 psi | 56% | 2087 fps | 100% |
| Accurate 2520 | <<locked>> | 80% | 41,031 psi | 66% | 2208 fps | 100% |
| Accurate 2700 | <<locked>> | 90% | 48,733 psi | 78% | 2267 fps | 95.2% |
| Accurate 4064 | <<locked>> | 80% | 32,938 psi | 53% | 2077 fps | 99.7% |
| Accurate 4350 | <<locked>> | 90% | 32,851 psi | 53% | 2136 fps | 95.1% |
| Accurate LT-30 | <<locked>> | 80% | 50,807 psi | 81% | 2218 fps | 100% |
| Accurate LT-32 | <<locked>> | 80% | 51,198 psi | 82% | 2238 fps | 100% |
| ADI AR 2206H | <<locked>> | 80% | 38,798 psi | 62% | 2169 fps | 98.1% |
| ADI AR 2208 | <<locked>> | 80% | 33,185 psi | 53% | 2047 fps | 95.7% |
| ADI AR 2219 | <<locked>> | 80% | 50,792 psi | 81% | 2316 fps | 100% |
| ADI Benchmark 8208 | <<locked>> | 80% | 40,770 psi | 65% | 2178 fps | 99.3% |
| Alliant AR-Comp | <<locked>> | 80% | 40,176 psi | 64% | 2175 fps | 100% |
| Alliant Power Pro 1200-R | <<locked>> | 80% | 47,239 psi | 76% | 2343 fps | 99.7% |
| Alliant Power Pro 2000-MR | 45.1 gr | 80% | 34,954 psi | 56% | 2178 fps | 95.8% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 32,343 psi | 52% | 2067 fps | 97.3% |
| Alliant Reloder-10x | <<locked>> | 80% | 48,109 psi | 77% | 2234 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 80% | 34,722 psi | 56% | 2113 fps | 96.5% |
| Alliant Reloder-16 | <<locked>> | 90% | 34,374 psi | 55% | 2149 fps | 95.3% |
| Alliant Reloder-17 | <<locked>> | 82% | 29,675 psi | 48% | 2070 fps | 95.3% |
| Alliant Reloder-23 | <<locked>> | 98% | 30,734 psi | 49% | 2103 fps | 95.5% |
| Baschieri & Pellagri 106 | <<locked>> | 80% | 49,647 psi | 80% | 2218 fps | 100% |
| Baschieri & Pellagri 107 | <<locked>> | 80% | 37,739 psi | 61% | 2172 fps | 96.7% |
| Bofors RP3 | <<locked>> | 80% | 31,488 psi | 50% | 2064 fps | 97.2% |
| Bofors RP7 | <<locked>> | 96% | 48,066 psi | 77% | 2297 fps | 95.4% |
| Hodgdon Benchmark | <<locked>> | 80% | 42,946 psi | 69% | 2175 fps | 99.8% |
| Hodgdon BL-C2 | <<locked>> | 80% | 38,914 psi | 62% | 2195 fps | 99.4% |
| Hodgdon CFE223 | <<locked>> | 80% | 42,815 psi | 69% | 2310 fps | 98.5% |
| Hodgdon H322 | <<locked>> | 80% | 46,644 psi | 75% | 2260 fps | 100% |
| Hodgdon H335 | <<locked>> | 80% | 47,166 psi | 76% | 2283 fps | 100% |
| Hodgdon H380 | <<locked>> | 82% | 34,969 psi | 56% | 2113 fps | 95.1% |
| Hodgdon H414 | <<locked>> | 96% | 43,859 psi | 70% | 2320 fps | 95.3% |
| Hodgdon H4350 | <<locked>> | 98% | 51,488 psi | 83% | 2382 fps | 95.5% |
| Hodgdon H4895 | <<locked>> | 80% | 39,073 psi | 63% | 2178 fps | 98.6% |
| Hodgdon Hybrid 100V | <<locked>> | 88% | 29,486 psi | 47% | 2021 fps | 95.4% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 34,954 psi | 56% | 2152 fps | 98.1% |
| Hodgdon Superformance | <<locked>> | 98% | 47,718 psi | 77% | 2388 fps | 95.3% |
| Hodgdon TrailBoss | <<locked>> | 80% | 25,976 psi | 42% | 1253 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 37,710 psi | 60% | 2142 fps | 98.2% |
| IMR 3031 | <<locked>> | 80% | 38,145 psi | 61% | 2178 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 34,780 psi | 56% | 2073 fps | 96.5% |
| IMR 4166 Enduron | <<locked>> | 86% | 45,078 psi | 72% | 2221 fps | 95.3% |
| IMR 4198 | <<locked>> | 80% | 48,646 psi | 78% | 2198 fps | 100% |
| IMR 4451 Enduron | <<locked>> | 92% | 44,280 psi | 71% | 2241 fps | 95% |
| IMR 4831 | <<locked>> | 92% | 34,432 psi | 55% | 2149 fps | 95.7% |
| IMR 4895 | <<locked>> | 80% | 35,505 psi | 57% | 2139 fps | 97.4% |
| IMR 8208 XBR | <<locked>> | 80% | 40,770 psi | 65% | 2178 fps | 99.3% |
| Lovex D073.5 | <<locked>> | 80% | 45,643 psi | 73% | 2251 fps | 100% |
| Lovex D073.6 | <<locked>> | 80% | 37,173 psi | 60% | 2152 fps | 99.7% |
| Lovex S060 | <<locked>> | 80% | 39,610 psi | 64% | 2123 fps | 98.2% |
| Lovex S062 | <<locked>> | 80% | 34,519 psi | 55% | 2080 fps | 98.3% |
| Lovex S065 | <<locked>> | 90% | 38,319 psi | 61% | 2152 fps | 95.1% |
| Lovex S070 | <<locked>> | 96% | 43,511 psi | 70% | 2260 fps | 95.3% |
| Norma 201 | <<locked>> | 80% | 38,116 psi | 61% | 2133 fps | 98.9% |
| Norma 202 | <<locked>> | 80% | 38,305 psi | 61% | 2146 fps | 100% |
| Norma 203B | <<locked>> | 80% | 34,098 psi | 55% | 2103 fps | 96.9% |
| Norma URP | <<locked>> | 90% | 33,924 psi | 54% | 2142 fps | 95.2% |
| Ramshot Big Game | <<locked>> | 80% | 33,547 psi | 54% | 2113 fps | 96.4% |
| Ramshot Hunter | <<locked>> | 96% | 40,422 psi | 65% | 2267 fps | 95.1% |
| Ramshot TAC | <<locked>> | 80% | 40,799 psi | 65% | 2182 fps | 96% |
| Ramshot Wild Boar | <<locked>> | 80% | 39,711 psi | 64% | 2195 fps | 98.2% |
| Ramshot X-Terminator | <<locked>> | 80% | 44,193 psi | 71% | 2221 fps | 98.9% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 26,049 psi | 42% | 1283 fps | 100% |
| ReloadSwiss RS 40 | <<locked>> | 80% | 45,948 psi | 74% | 2251 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 88% | 43,120 psi | 69% | 2234 fps | 95.6% |
| ReloadSwiss RS 52 | 43.7 gr | 80% | 35,752 psi | 57% | 2192 fps | 96.8% |
| ReloadSwiss RS 60 | 44.4 gr | 80% | 29,675 psi | 48% | 2080 fps | 97.9% |
| ReloadSwiss RS 62 | <<locked>> | 92% | 35,317 psi | 57% | 2198 fps | 95.4% |
| ReloadSwiss RS 70 | <<locked>> | 94% | 38,754 psi | 62% | 2254 fps | 95.4% |
| Rottweil R 901 | <<locked>> | 80% | 41,901 psi | 67% | 2172 fps | 100% |
| Rottweil R 902 | <<locked>> | 80% | 36,260 psi | 58% | 2093 fps | 98.6% |
| Rottweil R 903 | <<locked>> | 80% | 29,704 psi | 48% | 2018 fps | 96.2% |
| Rottweil R 907 | <<locked>> | 96% | 48,066 psi | 77% | 2297 fps | 95.4% |
| Shooters World Long Rifle | <<locked>> | 90% | 38,319 psi | 61% | 2152 fps | 95.1% |
| Shooters World Match Rifle | <<locked>> | 80% | 37,173 psi | 60% | 2152 fps | 99.7% |
| Shooters World Precision | <<locked>> | 80% | 34,519 psi | 55% | 2080 fps | 98.3% |
| Shooters World SW4350 | <<locked>> | 96% | 43,511 psi | 70% | 2260 fps | 95.3% |
| Shooters World Tactical Rifle | <<locked>> | 80% | 48,399 psi | 78% | 2264 fps | 99.8% |
| SNPE Vectan SP 10 | <<locked>> | 80% | 51,082 psi | 82% | 2326 fps | 100% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 30,806 psi | 49% | 2057 fps | 95.4% |
| SNPE Vectan SP 3 | <<locked>> | 80% | 48,544 psi | 78% | 2244 fps | 100% |
| SNPE Vectan SP 7 | <<locked>> | 80% | 38,624 psi | 62% | 2152 fps | 96.1% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 37,333 psi | 60% | 2142 fps | 97.7% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 39,740 psi | 64% | 2100 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 32,648 psi | 52% | 1988 fps | 99.8% |
| SNPE Vectan Tubal 7000 | <<locked>> | 96% | 45,542 psi | 73% | 2234 fps | 95.5% |
| Somchem S321 | <<locked>> | 80% | 43,830 psi | 70% | 2247 fps | 99.8% |
| Somchem S335 | <<locked>> | 80% | 39,247 psi | 63% | 2103 fps | 100% |
| Somchem S341 | <<locked>> | 80% | 38,479 psi | 62% | 2159 fps | 97.9% |
| Somchem S355 | <<locked>> | 80% | 30,763 psi | 49% | 2024 fps | 96.3% |
| Somchem S365 | <<locked>> | 86% | 26,832 psi | 43% | 2008 fps | 95.8% |
| Vihtavuori N130 | <<locked>> | 80% | 45,020 psi | 72% | 2152 fps | 100% |
| Vihtavuori N133 | <<locked>> | 80% | 39,871 psi | 64% | 2096 fps | 100% |
| Vihtavuori N135 | <<locked>> | 80% | 35,201 psi | 56% | 2083 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 36,158 psi | 58% | 2093 fps | 99.9% |
| Vihtavuori N150 | <<locked>> | 80% | 29,196 psi | 47% | 1975 fps | 97.2% |
| Vihtavuori N160 | <<locked>> | 90% | 35,534 psi | 57% | 2142 fps | 95.6% |
| Vihtavuori N530 | <<locked>> | 80% | 40,770 psi | 65% | 2175 fps | 99.3% |
| Vihtavuori N540 | <<locked>> | 80% | 34,737 psi | 56% | 2083 fps | 99.6% |
| Vihtavuori N550 | <<locked>> | 90% | 34,838 psi | 56% | 2149 fps | 95.3% |
| Vihtavuori N555 | <<locked>> | 98% | 32,489 psi | 52% | 2169 fps | 95.7% |
| Winchester 6.5 StaBALL | <<locked>> | 84% | 29,718 psi | 48% | 1995 fps | 95.4% |
| Winchester 748 | <<locked>> | 80% | 39,682 psi | 64% | 2211 fps | 99.7% |
| Winchester 760 | <<locked>> | 96% | 44,150 psi | 71% | 2323 fps | 95.3% |
| Winchester StaBALL Match | <<locked>> | 80% | 36,405 psi | 58% | 2146 fps | 98.1% |
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 106 powders for .338 RCM loaded with the .338 | 250gr | Sierra GameKing. Alliant Power Pro 2000-MR delivers the highest muzzle velocity at 2,533 fps; across all powders the maximum-charge window runs from 1,404 fps to 2,533 fps. Accurate 4350 gives the best case fill at 100 %, and 106 of the 106 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (430 MPa), the top charges use 52–90 %, leaving at least 10 % headroom. The 250.0 gr projectile in 0.338" calls for a 1:14.0 twist; slower twists will usually not stabilise this weight. Accurate 4350, Alliant Reloder-16, Alliant Reloder-17 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. Alliant Power Pro 2000-MR, ReloadSwiss RS 52, ReloadSwiss RS 60 rank at the top here: for .338 RCM with the .338 | 250gr | Sierra GameKing 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.