Load Specifications
Load data in caliber .450 Rigby with .458 | 450gr | Reichenberg Super Penetr. bullet and 97 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 60 and ReloadSwiss RS 52.
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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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% | 52,156 psi | 90% | 2303 fps | 100% |
| Accurate 2460 | <<locked>> | 84% | 50,256 psi | 87% | 2323 fps | 100% |
| Accurate 2495 | <<locked>> | 94% | 51,982 psi | 90% | 2352 fps | 100% |
| Accurate 2520 | <<locked>> | 88% | 51,619 psi | 89% | 2375 fps | 100% |
| Accurate 4064 | <<locked>> | 96% | 51,735 psi | 89% | 2392 fps | 100% |
| Accurate 4350ᴾ | <<locked>> | 100% | 44,077 psi | 76% | 2352 fps | 97.8% |
| Accurate LT-30 | <<locked>> | 82% | 52,475 psi | 90% | 2257 fps | 100% |
| ADI AR 2206H | <<locked>> | 90% | 51,169 psi | 88% | 2382 fps | 99.6% |
| ADI AR 2208 | <<locked>> | 96% | 52,112 psi | 90% | 2379 fps | 99.3% |
| ADI Benchmark 8208 | <<locked>> | 88% | 50,575 psi | 87% | 2346 fps | 99.9% |
| Alliant AR-Comp | <<locked>> | 88% | 50,111 psi | 86% | 2329 fps | 100% |
| Alliant Power Pro 1200-R | <<locked>> | 84% | 51,938 psi | 90% | 2431 fps | 99.9% |
| Alliant Power Pro 2000-MR | <<locked>> | 92% | 50,241 psi | 87% | 2474 fps | 99.1% |
| Alliant Reloder- TS 15.5 | <<locked>> | 96% | 51,010 psi | 88% | 2395 fps | 99.9% |
| Alliant Reloder-10x | <<locked>> | 84% | 52,098 psi | 90% | 2306 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 94% | 51,967 psi | 90% | 2415 fps | 99.4% |
| Alliant Reloder-16ᴾ | <<locked>> | 100% | 44,541 psi | 77% | 2362 fps | 98% |
| Alliant Reloder-17ᴾ | <<locked>> | 100% | 51,416 psi | 89% | 2497 fps | 99.9% |
| Baschieri & Pellagri 106 | <<locked>> | 82% | 51,155 psi | 88% | 2257 fps | 100% |
| Baschieri & Pellagri 107 | <<locked>> | 90% | 50,589 psi | 87% | 2395 fps | 98.9% |
| Bofors RP3 | <<locked>> | 96% | 51,010 psi | 88% | 2408 fps | 99.9% |
| Bofors RP7ᴾ | <<locked>> | 100% | 52,359 psi | 90% | 2375 fps | 95.9% |
| Hodgdon Benchmark | <<locked>> | 86% | 49,821 psi | 86% | 2293 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 90% | 52,286 psi | 90% | 2415 fps | 100% |
| Hodgdon CFE223 | <<locked>> | 86% | 50,647 psi | 87% | 2448 fps | 99.3% |
| Hodgdon H322 | <<locked>> | 84% | 51,256 psi | 88% | 2343 fps | 100% |
| Hodgdon H335 | <<locked>> | 84% | 52,025 psi | 90% | 2369 fps | 100% |
| Hodgdon H380 | <<locked>> | 94% | 49,371 psi | 85% | 2372 fps | 98.2% |
| Hodgdon H414ᴾ | <<locked>> | 100% | 48,008 psi | 83% | 2398 fps | 95.8% |
| Hodgdon H4895 | <<locked>> | 90% | 51,576 psi | 89% | 2392 fps | 99.8% |
| Hodgdon Hybrid 100Vᴾ | <<locked>> | 100% | 40,683 psi | 70% | 2264 fps | 98.5% |
| Hodgdon LEVERevolution | <<locked>> | 92% | 49,995 psi | 86% | 2418 fps | 99.9% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 34,563 psi | 60% | 1414 fps | 100% |
| Hodgdon VARGET | <<locked>> | 90% | 49,821 psi | 86% | 2352 fps | 99.7% |
| IMR 3031 | <<locked>> | 90% | 50,720 psi | 87% | 2379 fps | 100% |
| IMR 4064 | <<locked>> | 94% | 51,576 psi | 89% | 2365 fps | 99.4% |
| IMR 4166 Enduron | <<locked>> | 92% | 52,402 psi | 90% | 2346 fps | 96.5% |
| IMR 4198 | <<locked>> | 82% | 49,908 psi | 86% | 2238 fps | 100% |
| IMR 4451 Enduron | <<locked>> | 98% | 51,372 psi | 89% | 2362 fps | 96.2% |
| IMR 4831ᴾ | <<locked>> | 100% | 42,264 psi | 73% | 2306 fps | 97.5% |
| IMR 4895 | <<locked>> | 92% | 49,908 psi | 86% | 2395 fps | 99.5% |
| IMR 8208 XBR | <<locked>> | 88% | 50,575 psi | 87% | 2346 fps | 99.9% |
| Lovex D073.5 | <<locked>> | 84% | 50,140 psi | 86% | 2333 fps | 100% |
| Lovex D073.6 | <<locked>> | 90% | 49,777 psi | 86% | 2362 fps | 100% |
| Lovex S060 | <<locked>> | 90% | 51,692 psi | 89% | 2326 fps | 99.6% |
| Lovex S062 | <<locked>> | 94% | 50,792 psi | 88% | 2362 fps | 99.9% |
| Lovex S065ᴾ | <<locked>> | 100% | 49,835 psi | 86% | 2352 fps | 97.5% |
| Lovex S070ᴾ | <<locked>> | 100% | 47,036 psi | 81% | 2333 fps | 95.7% |
| Norma 201 | <<locked>> | 90% | 49,821 psi | 86% | 2336 fps | 99.9% |
| Norma 202 | <<locked>> | 90% | 50,154 psi | 86% | 2343 fps | 100% |
| Norma 203B | <<locked>> | 94% | 51,082 psi | 88% | 2405 fps | 99.6% |
| Norma URPᴾ | <<locked>> | 100% | 44,440 psi | 77% | 2349 fps | 97.7% |
| Ramshot Big Game | <<locked>> | 94% | 51,285 psi | 88% | 2428 fps | 99.5% |
| Ramshot TAC | <<locked>> | 88% | 50,966 psi | 88% | 2359 fps | 97.8% |
| Ramshot Wild Boar | <<locked>> | 88% | 49,879 psi | 86% | 2372 fps | 99.4% |
| Ramshot X-Terminator | <<locked>> | 86% | 51,692 psi | 89% | 2349 fps | 99.5% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 34,780 psi | 60% | 1447 fps | 100% |
| ReloadSwiss RS 40 | <<locked>> | 84% | 50,299 psi | 87% | 2333 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 94% | 50,212 psi | 87% | 2356 fps | 96.8% |
| ReloadSwiss RS 52 | <<locked>> | 92% | 51,677 psi | 89% | 2470 fps | 99.4% |
| ReloadSwiss RS 60 | <<locked>> | 98% | 51,329 psi | 88% | 2500 fps | 100% |
| ReloadSwiss RS 62ᴾ | <<locked>> | 100% | 44,034 psi | 76% | 2372 fps | 97.4% |
| ReloadSwiss RS 70ᴾ | <<locked>> | 100% | 45,513 psi | 78% | 2392 fps | 96.9% |
| Rottweil R 901 | <<locked>> | 88% | 50,865 psi | 88% | 2323 fps | 100% |
| Rottweil R 902 | <<locked>> | 92% | 50,140 psi | 86% | 2333 fps | 99.9% |
| Rottweil R 903 | <<locked>> | 98% | 50,734 psi | 87% | 2398 fps | 99.8% |
| Rottweil R 907ᴾ | <<locked>> | 100% | 52,359 psi | 90% | 2375 fps | 95.9% |
| Shooters World Long Rifleᴾ | <<locked>> | 100% | 49,835 psi | 86% | 2352 fps | 97.5% |
| Shooters World Match Rifle | <<locked>> | 90% | 49,777 psi | 86% | 2362 fps | 100% |
| Shooters World Precision | <<locked>> | 94% | 50,792 psi | 88% | 2362 fps | 99.9% |
| Shooters World SW4350ᴾ | <<locked>> | 100% | 47,036 psi | 81% | 2333 fps | 95.7% |
| Shooters World Tactical Rifle | <<locked>> | 82% | 50,053 psi | 86% | 2306 fps | 99.8% |
| SNPE Vectan SP 11 | <<locked>> | 96% | 49,458 psi | 85% | 2408 fps | 99.4% |
| SNPE Vectan SP 3 | <<locked>> | 82% | 50,125 psi | 86% | 2287 fps | 100% |
| SNPE Vectan SP 7 | <<locked>> | 90% | 52,127 psi | 90% | 2379 fps | 98.4% |
| SNPE Vectan SP 9 | <<locked>> | 90% | 49,588 psi | 85% | 2359 fps | 99.4% |
| SNPE Vectan Tubal 3000 | <<locked>> | 90% | 52,272 psi | 90% | 2293 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 96% | 51,561 psi | 89% | 2290 fps | 100% |
| SNPE Vectan Tubal 7000ᴾ | <<locked>> | 100% | 50,067 psi | 86% | 2313 fps | 96% |
| Somchem S321 | <<locked>> | 86% | 51,445 psi | 89% | 2375 fps | 100% |
| Somchem S335 | <<locked>> | 90% | 51,169 psi | 88% | 2293 fps | 100% |
| Somchem S341 | <<locked>> | 90% | 51,735 psi | 89% | 2379 fps | 99.5% |
| Somchem S355 | <<locked>> | 98% | 51,576 psi | 89% | 2398 fps | 99.8% |
| Somchem S365ᴾ | <<locked>> | 100% | 39,508 psi | 68% | 2306 fps | 99.4% |
| Vihtavuori N130 | <<locked>> | 86% | 52,228 psi | 90% | 2267 fps | 100% |
| Vihtavuori N133 | <<locked>> | 90% | 52,243 psi | 90% | 2283 fps | 100% |
| Vihtavuori N135 | <<locked>> | 92% | 49,211 psi | 85% | 2310 fps | 100% |
| Vihtavuori N140 | <<locked>> | 92% | 50,749 psi | 87% | 2326 fps | 100% |
| Vihtavuori N150 | <<locked>> | 98% | 49,835 psi | 86% | 2343 fps | 100% |
| Vihtavuori N160ᴾ | <<locked>> | 100% | 47,007 psi | 81% | 2352 fps | 98.1% |
| Vihtavuori N530 | <<locked>> | 88% | 51,024 psi | 88% | 2346 fps | 99.9% |
| Vihtavuori N540 | <<locked>> | 94% | 52,054 psi | 90% | 2365 fps | 100% |
| Vihtavuori N550ᴾ | <<locked>> | 100% | 45,818 psi | 79% | 2356 fps | 97.7% |
| Winchester 6.5 StaBALLᴾ | <<locked>> | 100% | 48,124 psi | 83% | 2343 fps | 99.6% |
| Winchester 748 | <<locked>> | 88% | 49,908 psi | 86% | 2385 fps | 100% |
| Winchester 760ᴾ | <<locked>> | 100% | 48,167 psi | 83% | 2402 fps | 95.8% |
| Winchester StaBALL Match | <<locked>> | 92% | 52,243 psi | 90% | 2408 fps | 99.8% |
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% | 40,582 psi | 70% | 2149 fps | 100% |
| Accurate 2460 | <<locked>> | 80% | 43,874 psi | 76% | 2238 fps | 100% |
| Accurate 2495 | <<locked>> | 80% | 32,576 psi | 56% | 2070 fps | 100% |
| Accurate 2520 | <<locked>> | 80% | 39,102 psi | 67% | 2195 fps | 99.7% |
| Accurate 4064 | <<locked>> | 80% | 30,864 psi | 53% | 2057 fps | 99.2% |
| Accurate 4350 | <<locked>> | 94% | 35,592 psi | 61% | 2208 fps | 95.6% |
| Accurate LT-30 | <<locked>> | 80% | 49,356 psi | 85% | 2221 fps | 100% |
| ADI AR 2206H | <<locked>> | 80% | 37,275 psi | 64% | 2159 fps | 97.3% |
| ADI AR 2208 | <<locked>> | 82% | 33,852 psi | 58% | 2077 fps | 95.4% |
| ADI Benchmark 8208 | <<locked>> | 80% | 39,320 psi | 68% | 2172 fps | 98.8% |
| Alliant AR-Comp | <<locked>> | 80% | 38,174 psi | 66% | 2169 fps | 100% |
| Alliant Power Pro 1200-R | <<locked>> | 80% | 45,498 psi | 78% | 2336 fps | 99.4% |
| Alliant Power Pro 2000-MR | 85.7 gr | 82% | 35,839 psi | 62% | 2215 fps | 95.6% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 30,560 psi | 53% | 2047 fps | 96.2% |
| Alliant Reloder-10x | <<locked>> | 80% | 46,064 psi | 79% | 2231 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 80% | 33,156 psi | 57% | 2096 fps | 95.4% |
| Alliant Reloder-16 | <<locked>> | 94% | 37,115 psi | 64% | 2224 fps | 95.8% |
| Alliant Reloder-17 | <<locked>> | 86% | 32,256 psi | 56% | 2149 fps | 95.9% |
| Baschieri & Pellagri 106 | <<locked>> | 80% | 48,022 psi | 83% | 2218 fps | 100% |
| Baschieri & Pellagri 107 | <<locked>> | 80% | 36,056 psi | 62% | 2156 fps | 95.7% |
| Bofors RP3 | <<locked>> | 80% | 29,617 psi | 51% | 2041 fps | 96% |
| Bofors RP7 | <<locked>> | 98% | 49,052 psi | 85% | 2329 fps | 95.1% |
| Hodgdon Benchmark | <<locked>> | 80% | 41,437 psi | 71% | 2169 fps | 99.4% |
| Hodgdon BL-C2 | <<locked>> | 80% | 37,144 psi | 64% | 2185 fps | 98.9% |
| Hodgdon CFE223 | <<locked>> | 80% | 40,901 psi | 71% | 2293 fps | 97.8% |
| Hodgdon H322 | <<locked>> | 80% | 44,933 psi | 77% | 2260 fps | 100% |
| Hodgdon H335 | <<locked>> | 80% | 45,397 psi | 78% | 2280 fps | 100% |
| Hodgdon H380 | <<locked>> | 86% | 37,840 psi | 65% | 2185 fps | 95.5% |
| Hodgdon H414 | <<locked>> | 98% | 44,976 psi | 78% | 2352 fps | 95% |
| Hodgdon H4895 | <<locked>> | 80% | 37,507 psi | 65% | 2169 fps | 97.9% |
| Hodgdon Hybrid 100V | <<locked>> | 92% | 31,662 psi | 55% | 2087 fps | 95.8% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 33,460 psi | 58% | 2136 fps | 97.2% |
| Hodgdon TrailBoss | <<locked>> | 80% | 25,498 psi | 44% | 1260 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 36,158 psi | 62% | 2129 fps | 97.5% |
| IMR 3031 | <<locked>> | 80% | 36,361 psi | 63% | 2172 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 33,272 psi | 57% | 2060 fps | 95.5% |
| IMR 4166 Enduron | <<locked>> | 88% | 46,296 psi | 80% | 2257 fps | 95.1% |
| IMR 4198 | <<locked>> | 80% | 47,108 psi | 81% | 2201 fps | 100% |
| IMR 4451 Enduron | <<locked>> | 96% | 48,225 psi | 83% | 2316 fps | 95.5% |
| IMR 4831 | <<locked>> | 94% | 34,795 psi | 60% | 2172 fps | 95.3% |
| IMR 4895 | <<locked>> | 80% | 33,924 psi | 58% | 2123 fps | 96.4% |
| IMR 8208 XBR | <<locked>> | 80% | 39,320 psi | 68% | 2172 fps | 98.8% |
| Lovex D073.5 | <<locked>> | 80% | 43,656 psi | 75% | 2241 fps | 99.8% |
| Lovex D073.6 | <<locked>> | 80% | 35,346 psi | 61% | 2139 fps | 99.3% |
| Lovex S060 | <<locked>> | 80% | 38,072 psi | 66% | 2113 fps | 97.5% |
| Lovex S062 | <<locked>> | 80% | 32,735 psi | 56% | 2064 fps | 97.4% |
| Lovex S065 | <<locked>> | 94% | 41,350 psi | 71% | 2224 fps | 95.5% |
| Lovex S070 | <<locked>> | 98% | 44,237 psi | 76% | 2287 fps | 95% |
| Norma 201 | <<locked>> | 80% | 36,376 psi | 63% | 2123 fps | 98.3% |
| Norma 202 | <<locked>> | 80% | 36,492 psi | 63% | 2136 fps | 99.7% |
| Norma 203B | <<locked>> | 80% | 32,561 psi | 56% | 2090 fps | 95.9% |
| Norma URP | <<locked>> | 94% | 36,709 psi | 63% | 2215 fps | 95.6% |
| Ramshot Big Game | <<locked>> | 80% | 32,010 psi | 55% | 2096 fps | 95.3% |
| Ramshot TAC | <<locked>> | 80% | 39,102 psi | 67% | 2169 fps | 95% |
| Ramshot Wild Boar | <<locked>> | 80% | 38,101 psi | 66% | 2185 fps | 97.5% |
| Ramshot X-Terminator | <<locked>> | 80% | 42,627 psi | 73% | 2215 fps | 98.3% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 25,788 psi | 44% | 1293 fps | 100% |
| ReloadSwiss RS 40 | <<locked>> | 80% | 44,150 psi | 76% | 2244 fps | 99.9% |
| ReloadSwiss RS 50 | <<locked>> | 90% | 44,019 psi | 76% | 2264 fps | 95.4% |
| ReloadSwiss RS 52 | 81 gr | 80% | 34,069 psi | 59% | 2172 fps | 95.7% |
| ReloadSwiss RS 60 | 82.3 gr | 80% | 28,239 psi | 49% | 2057 fps | 96.7% |
| ReloadSwiss RS 62 | <<locked>> | 94% | 35,897 psi | 62% | 2224 fps | 95% |
| ReloadSwiss RS 70 | <<locked>> | 96% | 39,711 psi | 68% | 2287 fps | 95.1% |
| Rottweil R 901 | <<locked>> | 80% | 39,871 psi | 69% | 2162 fps | 99.9% |
| Rottweil R 902 | <<locked>> | 80% | 34,606 psi | 60% | 2080 fps | 97.8% |
| Rottweil R 903 | <<locked>> | 82% | 29,878 psi | 52% | 2041 fps | 95.7% |
| Rottweil R 907 | <<locked>> | 98% | 49,052 psi | 85% | 2329 fps | 95.1% |
| Shooters World Long Rifle | <<locked>> | 94% | 41,350 psi | 71% | 2224 fps | 95.5% |
| Shooters World Match Rifle | <<locked>> | 80% | 35,346 psi | 61% | 2139 fps | 99.3% |
| Shooters World Precision | <<locked>> | 80% | 32,735 psi | 56% | 2064 fps | 97.4% |
| Shooters World SW4350 | <<locked>> | 98% | 44,237 psi | 76% | 2287 fps | 95% |
| Shooters World Tactical Rifle | <<locked>> | 80% | 46,702 psi | 81% | 2260 fps | 99.5% |
| SNPE Vectan SP 11 | <<locked>> | 82% | 31,386 psi | 54% | 2087 fps | 95.1% |
| SNPE Vectan SP 3 | <<locked>> | 80% | 46,992 psi | 81% | 2247 fps | 100% |
| SNPE Vectan SP 7 | <<locked>> | 80% | 36,912 psi | 64% | 2139 fps | 95% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 35,752 psi | 62% | 2133 fps | 96.8% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 38,232 psi | 66% | 2093 fps | 99.8% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 31,270 psi | 54% | 1982 fps | 99.5% |
| SNPE Vectan Tubal 7000 | <<locked>> | 98% | 46,688 psi | 80% | 2267 fps | 95.3% |
| Somchem S321 | <<locked>> | 80% | 41,916 psi | 72% | 2238 fps | 99.4% |
| Somchem S335 | <<locked>> | 80% | 37,623 psi | 65% | 2096 fps | 100% |
| Somchem S341 | <<locked>> | 80% | 36,666 psi | 63% | 2142 fps | 97% |
| Somchem S355 | <<locked>> | 80% | 29,182 psi | 50% | 2008 fps | 95.1% |
| Somchem S365 | <<locked>> | 88% | 26,890 psi | 46% | 2024 fps | 95.1% |
| Vihtavuori N130 | <<locked>> | 80% | 43,497 psi | 75% | 2156 fps | 100% |
| Vihtavuori N133 | <<locked>> | 80% | 38,392 psi | 66% | 2096 fps | 100% |
| Vihtavuori N135 | <<locked>> | 80% | 33,504 psi | 58% | 2077 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 34,447 psi | 59% | 2080 fps | 99.6% |
| Vihtavuori N150 | <<locked>> | 80% | 27,557 psi | 48% | 1955 fps | 96% |
| Vihtavuori N160 | <<locked>> | 92% | 36,201 psi | 62% | 2169 fps | 95.3% |
| Vihtavuori N530 | <<locked>> | 80% | 39,088 psi | 67% | 2165 fps | 98.8% |
| Vihtavuori N540 | <<locked>> | 80% | 33,040 psi | 57% | 2070 fps | 99.2% |
| Vihtavuori N550 | <<locked>> | 94% | 37,637 psi | 65% | 2218 fps | 95.6% |
| Winchester 6.5 StaBALL | <<locked>> | 86% | 30,371 psi | 52% | 2024 fps | 95.1% |
| Winchester 748 | <<locked>> | 80% | 37,942 psi | 65% | 2201 fps | 99.2% |
| Winchester 760 | <<locked>> | 98% | 45,092 psi | 78% | 2356 fps | 95% |
| Winchester StaBALL Match | <<locked>> | 80% | 34,809 psi | 60% | 2133 fps | 97.2% |
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 97 powders for .450 Rigby loaded with the .458 | 450gr | Reichenberg Super Penetr.. ReloadSwiss RS 60 delivers the highest muzzle velocity at 2,500 fps; across all powders the maximum-charge window runs from 1,414 fps to 2,500 fps. Accurate 4350 gives the best case fill at 100 %, and 97 of the 97 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (400 MPa), the top charges use 60–90 %, leaving at least 10 % headroom. The 450.0 gr projectile in 0.458" calls for a 1:6.0 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 60, ReloadSwiss RS 52 rank at the top here: for .450 Rigby with the .458 | 450gr | Reichenberg Super Penetr. 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.