Load Specifications
Load data in caliber .450 Rigby with .458 | 500gr | Hornady FMJ RN ENC bullet and 98 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 Alliant Reloder-17.
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: 24"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 2015 | <<locked>> | 86% | 52,344 psi | 90% | 2152 fps | 100% |
| Accurate 2460 | <<locked>> | 82% | 50,575 psi | 87% | 2175 fps | 100% |
| Accurate 2495 | <<locked>> | 90% | 49,734 psi | 86% | 2172 fps | 100% |
| Accurate 2520 | <<locked>> | 86% | 51,967 psi | 90% | 2224 fps | 100% |
| Accurate 2700 | <<locked>> | 90% | 50,111 psi | 86% | 2165 fps | 96.1% |
| Accurate 4064 | <<locked>> | 92% | 49,603 psi | 86% | 2208 fps | 100% |
| Accurate 4350ᴾ | <<locked>> | 100% | 48,138 psi | 83% | 2264 fps | 99.1% |
| ADI AR 2206H | <<locked>> | 88% | 51,300 psi | 88% | 2234 fps | 99.9% |
| ADI AR 2208 | <<locked>> | 94% | 52,054 psi | 90% | 2231 fps | 99.7% |
| ADI Benchmark 8208 | <<locked>> | 86% | 50,589 psi | 87% | 2195 fps | 100% |
| Alliant AR-Comp | <<locked>> | 86% | 50,502 psi | 87% | 2175 fps | 100% |
| Alliant Power Pro 1200-R | <<locked>> | 82% | 52,170 psi | 90% | 2277 fps | 100% |
| Alliant Power Pro 2000-MR | <<locked>> | 90% | 50,125 psi | 86% | 2323 fps | 99.6% |
| Alliant Reloder- TS 15.5 | <<locked>> | 94% | 51,372 psi | 89% | 2247 fps | 100% |
| Alliant Reloder-10x | <<locked>> | 82% | 52,228 psi | 90% | 2152 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 92% | 52,199 psi | 90% | 2267 fps | 99.8% |
| Alliant Reloder-16ᴾ | <<locked>> | 100% | 47,572 psi | 82% | 2267 fps | 99.2% |
| Alliant Reloder-17 | <<locked>> | 98% | 51,488 psi | 89% | 2346 fps | 100% |
| Alliant Reloder-23ᴾ | <<locked>> | 100% | 33,649 psi | 58% | 2057 fps | 97.4% |
| Baschieri & Pellagri 107 | <<locked>> | 88% | 50,488 psi | 87% | 2244 fps | 99.4% |
| Bofors RP3 | <<locked>> | 94% | 51,532 psi | 89% | 2260 fps | 100% |
| Bofors RP7 | <<locked>> | 98% | 52,359 psi | 90% | 2231 fps | 96.9% |
| Hodgdon Benchmark | <<locked>> | 84% | 49,545 psi | 85% | 2146 fps | 100% |
| Hodgdon BL-C2 | <<locked>> | 88% | 52,344 psi | 90% | 2260 fps | 100% |
| Hodgdon CFE223 | <<locked>> | 84% | 50,604 psi | 87% | 2293 fps | 99.7% |
| Hodgdon H322 | <<locked>> | 82% | 51,169 psi | 88% | 2188 fps | 100% |
| Hodgdon H335 | <<locked>> | 82% | 51,895 psi | 89% | 2215 fps | 100% |
| Hodgdon H380 | <<locked>> | 92% | 49,705 psi | 86% | 2231 fps | 98.9% |
| Hodgdon H414ᴾ | <<locked>> | 100% | 51,547 psi | 89% | 2306 fps | 97.5% |
| Hodgdon H4895 | <<locked>> | 88% | 51,721 psi | 89% | 2244 fps | 100% |
| Hodgdon Hybrid 100Vᴾ | <<locked>> | 100% | 43,700 psi | 75% | 2172 fps | 99.5% |
| Hodgdon LEVERevolution | <<locked>> | 90% | 50,154 psi | 86% | 2267 fps | 100% |
| Hodgdon Superformance | <<locked>> | 98% | 49,197 psi | 85% | 2287 fps | 96.3% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 35,027 psi | 60% | 1325 fps | 100% |
| Hodgdon VARGET | <<locked>> | 88% | 49,777 psi | 86% | 2205 fps | 99.9% |
| IMR 3031 | <<locked>> | 88% | 51,097 psi | 88% | 2228 fps | 100% |
| IMR 4064 | <<locked>> | 92% | 51,648 psi | 89% | 2218 fps | 99.7% |
| IMR 4166 Enduron | <<locked>> | 90% | 52,228 psi | 90% | 2201 fps | 97.4% |
| IMR 4350ᴾ | <<locked>> | 100% | 48,950 psi | 84% | 2211 fps | 96.2% |
| IMR 4451 Enduron | <<locked>> | 96% | 51,314 psi | 88% | 2221 fps | 97.1% |
| IMR 4831ᴾ | <<locked>> | 100% | 45,963 psi | 79% | 2218 fps | 98.9% |
| IMR 4895 | <<locked>> | 90% | 50,183 psi | 87% | 2251 fps | 99.9% |
| IMR 8208 XBR | <<locked>> | 86% | 50,589 psi | 87% | 2195 fps | 100% |
| Lovex D073.5 | <<locked>> | 82% | 50,241 psi | 87% | 2182 fps | 100% |
| Lovex D073.6 | <<locked>> | 88% | 50,212 psi | 87% | 2215 fps | 100% |
| Lovex S060 | <<locked>> | 88% | 51,416 psi | 89% | 2175 fps | 99.8% |
| Lovex S062 | <<locked>> | 92% | 51,271 psi | 88% | 2218 fps | 100% |
| Lovex S065 | <<locked>> | 98% | 50,067 psi | 86% | 2211 fps | 98.3% |
| Lovex S070ᴾ | <<locked>> | 100% | 50,604 psi | 87% | 2241 fps | 97.4% |
| Norma 201 | <<locked>> | 88% | 50,140 psi | 86% | 2192 fps | 100% |
| Norma 202 | <<locked>> | 88% | 50,386 psi | 87% | 2195 fps | 100% |
| Norma 203B | <<locked>> | 92% | 51,358 psi | 89% | 2257 fps | 99.9% |
| Norma URPᴾ | <<locked>> | 100% | 47,993 psi | 83% | 2257 fps | 99% |
| Ramshot Big Game | <<locked>> | 92% | 51,401 psi | 89% | 2277 fps | 99.8% |
| Ramshot Hunterᴾ | <<locked>> | 100% | 47,036 psi | 81% | 2251 fps | 97.4% |
| Ramshot TAC | <<locked>> | 86% | 50,749 psi | 87% | 2211 fps | 98.5% |
| Ramshot Wild Boar | <<locked>> | 86% | 49,922 psi | 86% | 2224 fps | 99.8% |
| Ramshot X-Terminator | <<locked>> | 84% | 51,474 psi | 89% | 2198 fps | 99.8% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 35,389 psi | 61% | 1358 fps | 100% |
| ReloadSwiss RS 40 | <<locked>> | 82% | 50,270 psi | 87% | 2182 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 92% | 50,328 psi | 87% | 2215 fps | 97.7% |
| ReloadSwiss RS 52 | <<locked>> | 90% | 52,025 psi | 90% | 2320 fps | 99.8% |
| ReloadSwiss RS 60 | <<locked>> | 96% | 51,358 psi | 89% | 2346 fps | 100% |
| ReloadSwiss RS 62ᴾ | <<locked>> | 100% | 47,805 psi | 82% | 2283 fps | 98.9% |
| ReloadSwiss RS 70ᴾ | <<locked>> | 100% | 48,631 psi | 84% | 2303 fps | 98.6% |
| Rottweil R 901 | <<locked>> | 86% | 51,430 psi | 89% | 2175 fps | 100% |
| Rottweil R 902 | <<locked>> | 90% | 50,488 psi | 87% | 2188 fps | 100% |
| Rottweil R 903 | <<locked>> | 96% | 51,416 psi | 89% | 2254 fps | 100% |
| Rottweil R 907 | <<locked>> | 98% | 52,359 psi | 90% | 2231 fps | 96.9% |
| Shooters World Long Rifle | <<locked>> | 98% | 50,067 psi | 86% | 2211 fps | 98.3% |
| Shooters World Match Rifle | <<locked>> | 88% | 50,212 psi | 87% | 2215 fps | 100% |
| Shooters World Precision | <<locked>> | 92% | 51,271 psi | 88% | 2218 fps | 100% |
| Shooters World SW4350ᴾ | <<locked>> | 100% | 50,604 psi | 87% | 2241 fps | 97.4% |
| SNPE Vectan SP 11 | <<locked>> | 94% | 49,617 psi | 86% | 2260 fps | 99.8% |
| SNPE Vectan SP 7 | <<locked>> | 88% | 52,199 psi | 90% | 2234 fps | 99.1% |
| SNPE Vectan SP 9 | <<locked>> | 88% | 49,501 psi | 85% | 2211 fps | 99.8% |
| SNPE Vectan Tubal 3000 | <<locked>> | 88% | 52,112 psi | 90% | 2142 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 94% | 51,677 psi | 89% | 2142 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 98% | 50,270 psi | 87% | 2175 fps | 97% |
| Somchem S321 | <<locked>> | 84% | 51,387 psi | 89% | 2224 fps | 100% |
| Somchem S335 | <<locked>> | 88% | 51,285 psi | 88% | 2146 fps | 100% |
| Somchem S341 | <<locked>> | 88% | 51,561 psi | 89% | 2228 fps | 99.8% |
| Somchem S355 | <<locked>> | 96% | 52,054 psi | 90% | 2251 fps | 100% |
| Somchem S365ᴾ | <<locked>> | 100% | 42,757 psi | 74% | 2218 fps | 100% |
| Vihtavuori N130 | <<locked>> | 84% | 52,199 psi | 90% | 2116 fps | 100% |
| Vihtavuori N133 | <<locked>> | 88% | 52,199 psi | 90% | 2133 fps | 100% |
| Vihtavuori N135 | <<locked>> | 90% | 49,850 psi | 86% | 2162 fps | 100% |
| Vihtavuori N140 | <<locked>> | 90% | 50,792 psi | 88% | 2175 fps | 100% |
| Vihtavuori N150 | <<locked>> | 96% | 50,169 psi | 86% | 2198 fps | 100% |
| Vihtavuori N160ᴾ | <<locked>> | 100% | 50,546 psi | 87% | 2254 fps | 99.2% |
| Vihtavuori N530 | <<locked>> | 86% | 50,923 psi | 88% | 2195 fps | 100% |
| Vihtavuori N540 | <<locked>> | 92% | 52,170 psi | 90% | 2215 fps | 100% |
| Vihtavuori N550ᴾ | <<locked>> | 100% | 49,429 psi | 85% | 2260 fps | 99% |
| Vihtavuori N555ᴾ | <<locked>> | 100% | 35,810 psi | 62% | 2119 fps | 97.4% |
| Winchester 6.5 StaBALLᴾ | <<locked>> | 100% | 51,358 psi | 89% | 2244 fps | 100% |
| Winchester 748 | <<locked>> | 86% | 50,169 psi | 86% | 2234 fps | 100% |
| Winchester 760ᴾ | <<locked>> | 100% | 51,721 psi | 89% | 2306 fps | 97.5% |
| Winchester StaBALL Match | <<locked>> | 90% | 52,344 psi | 90% | 2260 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% | 43,540 psi | 75% | 2044 fps | 100% |
| Accurate 2460 | <<locked>> | 80% | 47,268 psi | 81% | 2133 fps | 100% |
| Accurate 2495 | <<locked>> | 80% | 36,158 psi | 62% | 1988 fps | 100% |
| Accurate 2520 | <<locked>> | 80% | 42,395 psi | 73% | 2103 fps | 100% |
| Accurate 2700 | <<locked>> | 88% | 46,934 psi | 81% | 2123 fps | 95.4% |
| Accurate 4064 | <<locked>> | 80% | 34,200 psi | 59% | 1982 fps | 99.9% |
| Accurate 4350 | <<locked>> | 88% | 32,010 psi | 55% | 2001 fps | 95.4% |
| ADI AR 2206H | <<locked>> | 80% | 40,001 psi | 69% | 2070 fps | 98.7% |
| ADI AR 2208 | <<locked>> | 80% | 34,127 psi | 59% | 1952 fps | 96.5% |
| ADI Benchmark 8208 | <<locked>> | 80% | 42,032 psi | 72% | 2077 fps | 99.6% |
| Alliant AR-Comp | <<locked>> | 80% | 41,379 psi | 71% | 2067 fps | 100% |
| Alliant Power Pro 1200-R | <<locked>> | 80% | 48,820 psi | 84% | 2234 fps | 99.9% |
| Alliant Power Pro 2000-MR | 79.7 gr | 80% | 36,027 psi | 62% | 2087 fps | 96.8% |
| Alliant Reloder- TS 15.5 | <<locked>> | 80% | 33,344 psi | 57% | 1969 fps | 98% |
| Alliant Reloder-10x | <<locked>> | 80% | 49,269 psi | 85% | 2119 fps | 100% |
| Alliant Reloder-15 | <<locked>> | 80% | 35,897 psi | 62% | 2018 fps | 97.3% |
| Alliant Reloder-16 | <<locked>> | 88% | 33,272 psi | 57% | 2011 fps | 95.5% |
| Alliant Reloder-17 | 78.4 gr | 80% | 28,660 psi | 49% | 1936 fps | 95.4% |
| Alliant Reloder-23 | <<locked>> | 96% | 29,965 psi | 52% | 1975 fps | 95.8% |
| Baschieri & Pellagri 107 | <<locked>> | 80% | 38,812 psi | 67% | 2070 fps | 97.5% |
| Bofors RP3 | <<locked>> | 80% | 32,576 psi | 56% | 1972 fps | 97.9% |
| Bofors RP7 | <<locked>> | 94% | 46,340 psi | 80% | 2149 fps | 95.6% |
| Hodgdon Benchmark | <<locked>> | 80% | 43,918 psi | 76% | 2067 fps | 99.9% |
| Hodgdon BL-C2 | <<locked>> | 80% | 40,205 psi | 69% | 2093 fps | 99.7% |
| Hodgdon CFE223 | <<locked>> | 80% | 44,048 psi | 76% | 2201 fps | 99% |
| Hodgdon H322 | <<locked>> | 80% | 47,935 psi | 83% | 2149 fps | 100% |
| Hodgdon H335 | <<locked>> | 80% | 48,559 psi | 84% | 2172 fps | 100% |
| Hodgdon H380 | <<locked>> | 80% | 33,649 psi | 58% | 1972 fps | 95.2% |
| Hodgdon H414 | <<locked>> | 94% | 42,569 psi | 73% | 2175 fps | 95.5% |
| Hodgdon H4895 | <<locked>> | 80% | 40,321 psi | 70% | 2077 fps | 99.1% |
| Hodgdon Hybrid 100V | <<locked>> | 86% | 28,572 psi | 49% | 1890 fps | 95.6% |
| Hodgdon LEVERevolution | <<locked>> | 80% | 36,056 psi | 62% | 2054 fps | 98.7% |
| Hodgdon Superformance | <<locked>> | 96% | 45,847 psi | 79% | 2238 fps | 95.4% |
| Hodgdon TrailBoss | <<locked>> | 80% | 26,063 psi | 45% | 1181 fps | 100% |
| Hodgdon VARGET | <<locked>> | 80% | 38,711 psi | 67% | 2041 fps | 98.8% |
| IMR 3031 | <<locked>> | 80% | 39,552 psi | 68% | 2077 fps | 100% |
| IMR 4064 | <<locked>> | 80% | 35,737 psi | 62% | 1978 fps | 97.3% |
| IMR 4166 Enduron | <<locked>> | 84% | 43,366 psi | 75% | 2077 fps | 95.4% |
| IMR 4350 | <<locked>> | 98% | 46,035 psi | 79% | 2169 fps | 95.5% |
| IMR 4451 Enduron | <<locked>> | 90% | 42,786 psi | 74% | 2096 fps | 95.2% |
| IMR 4831 | <<locked>> | 88% | 31,285 psi | 54% | 1969 fps | 95% |
| IMR 4895 | <<locked>> | 80% | 36,709 psi | 63% | 2041 fps | 98.1% |
| IMR 8208 XBR | <<locked>> | 80% | 42,032 psi | 72% | 2077 fps | 99.6% |
| Lovex D073.5 | <<locked>> | 80% | 46,992 psi | 81% | 2142 fps | 100% |
| Lovex D073.6 | <<locked>> | 80% | 38,551 psi | 66% | 2054 fps | 99.9% |
| Lovex S060 | <<locked>> | 80% | 40,669 psi | 70% | 2021 fps | 98.8% |
| Lovex S062 | <<locked>> | 80% | 35,578 psi | 61% | 1985 fps | 98.8% |
| Lovex S065 | <<locked>> | 88% | 37,159 psi | 64% | 2014 fps | 95.3% |
| Lovex S070 | <<locked>> | 94% | 42,003 psi | 72% | 2113 fps | 95.5% |
| Norma 201 | <<locked>> | 80% | 39,291 psi | 68% | 2034 fps | 99.4% |
| Norma 202 | <<locked>> | 80% | 39,363 psi | 68% | 2041 fps | 100% |
| Norma 203B | <<locked>> | 80% | 35,259 psi | 61% | 2008 fps | 97.7% |
| Norma URP | <<locked>> | 88% | 32,953 psi | 57% | 2005 fps | 95.4% |
| Ramshot Big Game | <<locked>> | 80% | 34,621 psi | 60% | 2018 fps | 97.3% |
| Ramshot Hunter | <<locked>> | 94% | 38,986 psi | 67% | 2119 fps | 95.3% |
| Ramshot TAC | <<locked>> | 80% | 41,742 psi | 72% | 2080 fps | 96.8% |
| Ramshot Wild Boar | <<locked>> | 80% | 40,930 psi | 71% | 2096 fps | 98.8% |
| Ramshot X-Terminator | <<locked>> | 80% | 45,266 psi | 78% | 2116 fps | 99.3% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 26,339 psi | 45% | 1211 fps | 100% |
| ReloadSwiss RS 40 | <<locked>> | 80% | 47,021 psi | 81% | 2139 fps | 100% |
| ReloadSwiss RS 50 | <<locked>> | 84% | 38,986 psi | 67% | 2044 fps | 95% |
| ReloadSwiss RS 52 | <<locked>> | 80% | 36,985 psi | 64% | 2093 fps | 97.7% |
| ReloadSwiss RS 60 | 78.4 gr | 80% | 30,530 psi | 53% | 1991 fps | 98.7% |
| ReloadSwiss RS 62 | <<locked>> | 90% | 34,287 psi | 59% | 2060 fps | 95.6% |
| ReloadSwiss RS 70 | <<locked>> | 92% | 37,376 psi | 64% | 2113 fps | 95.5% |
| Rottweil R 901 | <<locked>> | 80% | 43,033 psi | 74% | 2064 fps | 100% |
| Rottweil R 902 | <<locked>> | 80% | 37,362 psi | 64% | 1995 fps | 99.1% |
| Rottweil R 903 | <<locked>> | 80% | 30,734 psi | 53% | 1926 fps | 97.1% |
| Rottweil R 907 | <<locked>> | 94% | 46,340 psi | 80% | 2149 fps | 95.6% |
| Shooters World Long Rifle | <<locked>> | 88% | 37,159 psi | 64% | 2014 fps | 95.3% |
| Shooters World Match Rifle | <<locked>> | 80% | 38,551 psi | 66% | 2054 fps | 99.9% |
| Shooters World Precision | <<locked>> | 80% | 35,578 psi | 61% | 1985 fps | 98.8% |
| Shooters World SW4350 | <<locked>> | 94% | 42,003 psi | 72% | 2113 fps | 95.5% |
| SNPE Vectan SP 11 | <<locked>> | 80% | 31,720 psi | 55% | 1965 fps | 96.4% |
| SNPE Vectan SP 7 | <<locked>> | 80% | 39,755 psi | 69% | 2057 fps | 96.9% |
| SNPE Vectan SP 9 | <<locked>> | 80% | 38,435 psi | 66% | 2044 fps | 98.3% |
| SNPE Vectan Tubal 3000 | <<locked>> | 80% | 40,828 psi | 70% | 1995 fps | 100% |
| SNPE Vectan Tubal 5000 | <<locked>> | 80% | 33,663 psi | 58% | 1896 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 92% | 41,249 psi | 71% | 2051 fps | 95% |
| Somchem S321 | <<locked>> | 80% | 45,034 psi | 78% | 2139 fps | 99.9% |
| Somchem S335 | <<locked>> | 80% | 40,393 psi | 70% | 2001 fps | 100% |
| Somchem S341 | <<locked>> | 80% | 39,566 psi | 68% | 2057 fps | 98.5% |
| Somchem S355 | <<locked>> | 80% | 31,836 psi | 55% | 1932 fps | 97.1% |
| Somchem S365 | <<locked>> | 82% | 24,410 psi | 42% | 1837 fps | 95% |
| Vihtavuori N130 | <<locked>> | 80% | 46,253 psi | 80% | 2044 fps | 100% |
| Vihtavuori N133 | <<locked>> | 80% | 41,046 psi | 71% | 1991 fps | 100% |
| Vihtavuori N135 | <<locked>> | 80% | 36,419 psi | 63% | 1982 fps | 100% |
| Vihtavuori N140 | <<locked>> | 80% | 37,202 psi | 64% | 1991 fps | 100% |
| Vihtavuori N150 | <<locked>> | 80% | 30,139 psi | 52% | 1886 fps | 97.9% |
| Vihtavuori N160 | <<locked>> | 86% | 32,430 psi | 56% | 1965 fps | 95% |
| Vihtavuori N530 | <<locked>> | 80% | 41,945 psi | 72% | 2073 fps | 99.7% |
| Vihtavuori N540 | <<locked>> | 80% | 35,679 psi | 62% | 1985 fps | 99.9% |
| Vihtavuori N550 | <<locked>> | 88% | 33,765 psi | 58% | 2011 fps | 95.4% |
| Vihtavuori N555 | <<locked>> | 94% | 29,747 psi | 51% | 1991 fps | 95.1% |
| Winchester 6.5 StaBALL | <<locked>> | 82% | 28,761 psi | 50% | 1867 fps | 95.6% |
| Winchester 748 | <<locked>> | 80% | 41,046 psi | 71% | 2110 fps | 99.9% |
| Winchester 760 | <<locked>> | 94% | 42,728 psi | 74% | 2175 fps | 95.5% |
| Winchester StaBALL Match | <<locked>> | 80% | 37,565 psi | 65% | 2047 fps | 98.7% |
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 98 powders for .450 Rigby loaded with the .458 | 500gr | Hornady FMJ RN ENC. Alliant Reloder-17 delivers the highest muzzle velocity at 2,346 fps; across all powders the maximum-charge window runs from 1,325 fps to 2,346 fps. Accurate 4350 gives the best case fill at 100 %, and 98 of the 98 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (400 MPa), the top charges use 58–90 %, leaving at least 10 % headroom. The 500.0 gr projectile in 0.458" calls for a 1:23.5 twist; slower twists will usually not stabilise this weight. Accurate 4350, Alliant Reloder-16, Alliant Reloder-23 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, Alliant Reloder-17 rank at the top here: for .450 Rigby with the .458 | 500gr | Hornady FMJ RN ENC 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.