Load Specifications
Load data in caliber 7.21 Firebird with .283 | 140gr | Rhino Penetrator bullet and 52 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Hodgdon Retumbo, ADI AR 2218 and Vihtavuori N570.
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: 26"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 3100 | <<locked>> | 86% | 58,508 psi | 88% | 3179 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 50,705 psi | 76% | 3140 fps | 96.9% |
| Accurate MAGPRO | <<locked>> | 84% | 57,740 psi | 87% | 3301 fps | 99.6% |
| ADI AR 2209 | <<locked>> | 84% | 59,393 psi | 89% | 3278 fps | 100% |
| ADI AR 2213 | <<locked>> | 86% | 58,334 psi | 87% | 3297 fps | 100% |
| ADI AR 2217 | <<locked>> | 94% | 57,798 psi | 87% | 3274 fps | 100% |
| ADI AR 2218 | <<locked>> | 98% | 58,958 psi | 88% | 3415 fps | 99.2% |
| ADI AR 2225 | <<locked>> | 96% | 57,537 psi | 86% | 3297 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 84% | 58,972 psi | 88% | 3264 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 86% | 58,813 psi | 88% | 3287 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 86% | 56,985 psi | 85% | 3186 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 90% | 57,798 psi | 87% | 3264 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 82% | 57,914 psi | 87% | 3274 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 94% | 56,753 psi | 85% | 3310 fps | 98.6% |
| Alliant Reloder-50 | <<locked>> | 98% | 57,116 psi | 86% | 3301 fps | 98.2% |
| Baschieri & Pellagri 109 | <<locked>> | 88% | 58,479 psi | 88% | 3245 fps | 98.9% |
| Bofors RP15 | <<locked>> | 88% | 58,175 psi | 87% | 3278 fps | 100% |
| Bofors RP30 | <<locked>> | 92% | 57,754 psi | 87% | 3287 fps | 100% |
| Bofors RP5 | <<locked>> | 86% | 58,813 psi | 88% | 3287 fps | 100% |
| Hodgdon H1000 | <<locked>> | 92% | 59,277 psi | 89% | 3294 fps | 100% |
| Hodgdon H4831 | <<locked>> | 84% | 56,956 psi | 85% | 3222 fps | 99.7% |
| Hodgdon H4831 SC | <<locked>> | 86% | 59,785 psi | 90% | 3268 fps | 99.9% |
| Hodgdon Hybrid 100V | <<locked>> | 82% | 59,364 psi | 89% | 3166 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 90% | 57,624 psi | 86% | 3366 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,956 psi | 57% | 2123 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 84% | 56,942 psi | 85% | 3196 fps | 99.7% |
| IMR 7828 SSC | <<locked>> | 86% | 56,811 psi | 85% | 3278 fps | 99.9% |
| IMR 7977 Enduron | <<locked>> | 92% | 59,466 psi | 89% | 3199 fps | 96.2% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 60,307 psi | 90% | 3340 fps | 100% |
| Lovex S071 | <<locked>> | 90% | 56,826 psi | 85% | 3153 fps | 100% |
| Norma 217 | <<locked>> | 98% | 58,030 psi | 87% | 3304 fps | 100% |
| Norma MRP | <<locked>> | 84% | 59,088 psi | 89% | 3304 fps | 100% |
| Ramshot Grand | <<locked>> | 86% | 58,436 psi | 88% | 3304 fps | 100% |
| Ramshot Magnum | <<locked>> | 88% | 56,971 psi | 85% | 3222 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,870 psi | 58% | 2169 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 90% | 58,711 psi | 88% | 3346 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 92% | 57,972 psi | 87% | 3317 fps | 99.8% |
| Rottweil R 904 | <<locked>> | 84% | 59,437 psi | 89% | 3241 fps | 100% |
| Rottweil R 905 | <<locked>> | 84% | 58,784 psi | 88% | 3258 fps | 100% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 52,518 psi | 79% | 3150 fps | 96.9% |
| SNPE Vectan Tubal 8000 | <<locked>> | 84% | 58,407 psi | 88% | 3251 fps | 100% |
| Somchem S361 | <<locked>> | 82% | 57,232 psi | 86% | 3166 fps | 99.7% |
| Somchem S385 | <<locked>> | 84% | 59,059 psi | 89% | 3219 fps | 100% |
| Vihtavuori N165 | <<locked>> | 88% | 59,277 psi | 89% | 3205 fps | 100% |
| Vihtavuori N170 | <<locked>> | 92% | 58,842 psi | 88% | 3238 fps | 97.6% |
| Vihtavuori N555 | <<locked>> | 84% | 58,697 psi | 88% | 3219 fps | 100% |
| Vihtavuori N560 | <<locked>> | 84% | 58,320 psi | 87% | 3310 fps | 99.8% |
| Vihtavuori N565 | <<locked>> | 90% | 59,959 psi | 90% | 3304 fps | 100% |
| Vihtavuori N568 | <<locked>> | 92% | 58,204 psi | 87% | 3320 fps | 99.6% |
| Vihtavuori N570 | <<locked>> | 94% | 59,741 psi | 90% | 3392 fps | 98.7% |
| Winchester StaBALL HD | <<locked>> | 86% | 58,189 psi | 87% | 3284 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 86% | 59,176 psi | 89% | 3219 fps | 100% |
Recommended = one of the top powders for this cartridge and bullet combination.
Start Load - Barrel Length: 26"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 3100 | <<locked>> | 80% | 47,732 psi | 72% | 3005 fps | 100% |
| Accurate 8700 | <<locked>> | 98% | 46,949 psi | 70% | 3068 fps | 95.9% |
| Accurate MAGPRO | <<locked>> | 80% | 50,053 psi | 75% | 3156 fps | 98.6% |
| ADI AR 2209 | <<locked>> | 80% | 51,895 psi | 78% | 3150 fps | 99.9% |
| ADI AR 2213 | <<locked>> | 80% | 47,137 psi | 71% | 3094 fps | 98.9% |
| ADI AR 2217 | <<locked>> | 80% | 35,157 psi | 53% | 2805 fps | 95.9% |
| ADI AR 2218 | 98.9 gr | 90% | 43,555 psi | 65% | 3091 fps | 95.2% |
| ADI AR 2225 | <<locked>> | 80% | 32,590 psi | 49% | 2776 fps | 97.9% |
| Alliant Reloder-19 | <<locked>> | 80% | 51,590 psi | 77% | 3140 fps | 99.9% |
| Alliant Reloder-22 | <<locked>> | 80% | 47,906 psi | 72% | 3097 fps | 99.6% |
| Alliant Reloder-23 | <<locked>> | 80% | 46,572 psi | 70% | 3015 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 40,872 psi | 61% | 2963 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 80% | 53,766 psi | 81% | 3212 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 88% | 45,179 psi | 68% | 3084 fps | 95.8% |
| Alliant Reloder-50 | <<locked>> | 92% | 45,513 psi | 68% | 3077 fps | 95.3% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 44,889 psi | 67% | 2989 fps | 96% |
| Bofors RP15 | <<locked>> | 80% | 44,556 psi | 67% | 3025 fps | 99.1% |
| Bofors RP30 | <<locked>> | 80% | 38,101 psi | 57% | 2890 fps | 97.1% |
| Bofors RP5 | <<locked>> | 80% | 47,906 psi | 72% | 3097 fps | 99.6% |
| Hodgdon H1000 | <<locked>> | 80% | 38,290 psi | 57% | 2890 fps | 97.7% |
| Hodgdon H4831 | <<locked>> | 80% | 49,617 psi | 74% | 3091 fps | 98.9% |
| Hodgdon H4831 SC | <<locked>> | 80% | 48,646 psi | 73% | 3071 fps | 98.7% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 55,593 psi | 83% | 3114 fps | 100% |
| Hodgdon Retumbo | 83 gr | 80% | 39,943 psi | 60% | 3022 fps | 99.1% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,442 psi | 43% | 1903 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 50,067 psi | 75% | 3071 fps | 99% |
| IMR 7828 SSC | <<locked>> | 80% | 46,006 psi | 69% | 3077 fps | 98.7% |
| IMR 7977 Enduron | <<locked>> | 90% | 55,608 psi | 83% | 3133 fps | 95.4% |
| IMR 8133 Enduron | <<locked>> | 84% | 34,751 psi | 52% | 2818 fps | 95.6% |
| Lovex S071 | <<locked>> | 80% | 41,249 psi | 62% | 2874 fps | 99.8% |
| Norma 217 | <<locked>> | 80% | 30,487 psi | 46% | 2710 fps | 95.9% |
| Norma MRP | <<locked>> | 80% | 51,285 psi | 77% | 3173 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 46,644 psi | 70% | 3094 fps | 99.1% |
| Ramshot Magnum | <<locked>> | 80% | 42,105 psi | 63% | 2953 fps | 99.4% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,182 psi | 44% | 1949 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 39,610 psi | 59% | 2992 fps | 99.7% |
| ReloadSwiss RS 80 | <<locked>> | 82% | 39,523 psi | 59% | 2946 fps | 96% |
| Rottweil R 904 | <<locked>> | 80% | 52,330 psi | 78% | 3123 fps | 99.6% |
| Rottweil R 905 | <<locked>> | 80% | 51,401 psi | 77% | 3130 fps | 99.9% |
| SNPE Vectan SP 13 | <<locked>> | 96% | 45,643 psi | 68% | 3015 fps | 95% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 51,053 psi | 77% | 3130 fps | 99.9% |
| Somchem S361 | <<locked>> | 80% | 53,534 psi | 80% | 3104 fps | 99.4% |
| Somchem S385 | <<locked>> | 80% | 51,721 psi | 78% | 3100 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 45,368 psi | 68% | 2969 fps | 99.6% |
| Vihtavuori N170 | <<locked>> | 86% | 48,022 psi | 72% | 3035 fps | 95% |
| Vihtavuori N555 | <<locked>> | 80% | 51,401 psi | 77% | 3104 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 50,662 psi | 76% | 3173 fps | 99.1% |
| Vihtavuori N565 | <<locked>> | 80% | 42,496 psi | 64% | 2976 fps | 97.7% |
| Vihtavuori N568 | <<locked>> | 82% | 40,350 psi | 60% | 2959 fps | 95.7% |
| Vihtavuori N570 | 92.6 gr | 86% | 44,599 psi | 67% | 3094 fps | 95% |
| Winchester StaBALL HD | <<locked>> | 80% | 46,311 psi | 69% | 3094 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 47,935 psi | 72% | 3028 fps | 99.6% |
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 59 powders for 7.21 Firebird loaded with the .283 | 140gr | Rhino Penetrator. ADI AR 2218 delivers the highest muzzle velocity at 3,415 fps; across all powders the maximum-charge window runs from 2,123 fps to 3,415 fps. Accurate 8700 gives the best case fill at 100 %, and 59 of the 59 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (460 MPa), the top charges use 57–90 %, leaving at least 10 % headroom. The 140.0 gr projectile in 0.283" calls for a 1:10.5 twist; slower twists will usually not stabilise this weight. Accurate 8700, Hodgdon TrailBoss, Hodgdon US 869 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. Hodgdon Retumbo, ADI AR 2218, Vihtavuori N570 rank at the top here: for 7.21 Firebird with the .283 | 140gr | Rhino Penetrator they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Hodgdon 50BMG, Hodgdon US 869, Lovex D100 burn incompletely and react more sensitively to barrel length and temperature. Always begin at the start load and work up in small increments while checking case and primer for pressure signs.