Load Specifications
Load data in caliber 7.21 Firebird with .283 | 140gr | Frontier PH HPBT 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% | 58,392 psi | 88% | 3179 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 50,430 psi | 76% | 3136 fps | 96.8% |
| Accurate MAGPRO | <<locked>> | 84% | 57,624 psi | 86% | 3301 fps | 99.6% |
| ADI AR 2209 | <<locked>> | 84% | 59,248 psi | 89% | 3274 fps | 100% |
| ADI AR 2213 | <<locked>> | 86% | 58,204 psi | 87% | 3297 fps | 100% |
| ADI AR 2217 | <<locked>> | 94% | 57,653 psi | 86% | 3274 fps | 100% |
| ADI AR 2218 | <<locked>> | 98% | 58,856 psi | 88% | 3412 fps | 99.2% |
| ADI AR 2225 | <<locked>> | 96% | 57,435 psi | 86% | 3297 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 84% | 58,842 psi | 88% | 3264 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 86% | 58,682 psi | 88% | 3287 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 86% | 56,840 psi | 85% | 3186 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 90% | 57,682 psi | 86% | 3264 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 82% | 57,740 psi | 87% | 3274 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 94% | 56,637 psi | 85% | 3310 fps | 98.5% |
| Alliant Reloder-50 | <<locked>> | 98% | 56,826 psi | 85% | 3301 fps | 98.2% |
| Baschieri & Pellagri 109 | <<locked>> | 88% | 58,349 psi | 87% | 3245 fps | 98.9% |
| Bofors RP15 | <<locked>> | 88% | 58,059 psi | 87% | 3278 fps | 100% |
| Bofors RP30 | <<locked>> | 92% | 57,653 psi | 86% | 3287 fps | 100% |
| Bofors RP5 | <<locked>> | 86% | 58,682 psi | 88% | 3287 fps | 100% |
| Hodgdon H1000 | <<locked>> | 92% | 59,117 psi | 89% | 3294 fps | 100% |
| Hodgdon H4831 | <<locked>> | 84% | 56,782 psi | 85% | 3222 fps | 99.7% |
| Hodgdon H4831 SC | <<locked>> | 86% | 59,669 psi | 89% | 3268 fps | 99.9% |
| Hodgdon Hybrid 100V | <<locked>> | 82% | 59,393 psi | 89% | 3169 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 90% | 57,232 psi | 86% | 3363 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,913 psi | 57% | 2123 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 84% | 56,826 psi | 85% | 3196 fps | 99.7% |
| IMR 7828 SSC | <<locked>> | 86% | 56,666 psi | 85% | 3278 fps | 99.9% |
| IMR 7977 Enduron | <<locked>> | 92% | 59,350 psi | 89% | 3199 fps | 96.2% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 60,220 psi | 90% | 3340 fps | 100% |
| Lovex S071 | <<locked>> | 90% | 56,695 psi | 85% | 3153 fps | 100% |
| Norma 217 | <<locked>> | 98% | 57,667 psi | 86% | 3297 fps | 100% |
| Norma MRP | <<locked>> | 84% | 58,943 psi | 88% | 3304 fps | 100% |
| Ramshot Grand | <<locked>> | 86% | 58,291 psi | 87% | 3304 fps | 100% |
| Ramshot Magnum | <<locked>> | 88% | 56,855 psi | 85% | 3222 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,972 psi | 58% | 2172 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 90% | 58,581 psi | 88% | 3346 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 92% | 57,682 psi | 86% | 3314 fps | 99.7% |
| Rottweil R 904 | <<locked>> | 84% | 59,306 psi | 89% | 3241 fps | 100% |
| Rottweil R 905 | <<locked>> | 84% | 58,639 psi | 88% | 3255 fps | 100% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 52,402 psi | 79% | 3153 fps | 96.9% |
| SNPE Vectan Tubal 8000 | <<locked>> | 84% | 58,262 psi | 87% | 3251 fps | 100% |
| Somchem S361 | <<locked>> | 82% | 57,130 psi | 86% | 3166 fps | 99.7% |
| Somchem S385 | <<locked>> | 84% | 58,929 psi | 88% | 3219 fps | 100% |
| Vihtavuori N165 | <<locked>> | 88% | 59,176 psi | 89% | 3205 fps | 100% |
| Vihtavuori N170 | <<locked>> | 92% | 58,726 psi | 88% | 3235 fps | 97.6% |
| Vihtavuori N555 | <<locked>> | 84% | 58,537 psi | 88% | 3219 fps | 100% |
| Vihtavuori N560 | <<locked>> | 84% | 58,146 psi | 87% | 3307 fps | 99.8% |
| Vihtavuori N565 | <<locked>> | 90% | 59,799 psi | 90% | 3304 fps | 100% |
| Vihtavuori N568 | <<locked>> | 92% | 57,856 psi | 87% | 3317 fps | 99.5% |
| Vihtavuori N570 | <<locked>> | 94% | 59,596 psi | 89% | 3392 fps | 98.7% |
| Winchester StaBALL HD | <<locked>> | 86% | 58,030 psi | 87% | 3284 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 86% | 58,871 psi | 88% | 3215 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% | 47,630 psi | 71% | 3005 fps | 100% |
| Accurate 8700 | <<locked>> | 98% | 46,847 psi | 70% | 3064 fps | 95.8% |
| Accurate MAGPRO | <<locked>> | 80% | 49,893 psi | 75% | 3159 fps | 98.6% |
| ADI AR 2209 | <<locked>> | 80% | 51,750 psi | 78% | 3153 fps | 99.9% |
| ADI AR 2213 | <<locked>> | 80% | 46,992 psi | 70% | 3091 fps | 98.9% |
| ADI AR 2217 | <<locked>> | 80% | 35,056 psi | 53% | 2805 fps | 95.9% |
| ADI AR 2218 | 98.7 gr | 90% | 43,439 psi | 65% | 3091 fps | 95.2% |
| ADI AR 2225 | <<locked>> | 80% | 32,474 psi | 49% | 2776 fps | 97.9% |
| Alliant Reloder-19 | <<locked>> | 80% | 51,459 psi | 77% | 3140 fps | 99.9% |
| Alliant Reloder-22 | <<locked>> | 80% | 47,761 psi | 72% | 3094 fps | 99.6% |
| Alliant Reloder-23 | <<locked>> | 80% | 46,601 psi | 70% | 3022 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 40,727 psi | 61% | 2963 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 80% | 53,592 psi | 80% | 3212 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 88% | 45,063 psi | 68% | 3084 fps | 95.7% |
| Alliant Reloder-50 | <<locked>> | 92% | 45,252 psi | 68% | 3074 fps | 95.2% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 44,788 psi | 67% | 2989 fps | 96% |
| Bofors RP15 | <<locked>> | 80% | 44,411 psi | 67% | 3022 fps | 99.1% |
| Bofors RP30 | <<locked>> | 80% | 38,000 psi | 57% | 2890 fps | 97% |
| Bofors RP5 | <<locked>> | 80% | 47,761 psi | 72% | 3094 fps | 99.6% |
| Hodgdon H1000 | <<locked>> | 80% | 38,319 psi | 57% | 2894 fps | 97.8% |
| Hodgdon H4831 | <<locked>> | 80% | 49,487 psi | 74% | 3087 fps | 98.8% |
| Hodgdon H4831 SC | <<locked>> | 80% | 48,501 psi | 73% | 3071 fps | 98.7% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 55,651 psi | 83% | 3114 fps | 100% |
| Hodgdon Retumbo | 82.8 gr | 80% | 39,813 psi | 60% | 3018 fps | 99.1% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,398 psi | 43% | 1903 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 49,951 psi | 75% | 3074 fps | 99% |
| IMR 7828 SSC | <<locked>> | 80% | 45,861 psi | 69% | 3074 fps | 98.7% |
| IMR 7977 Enduron | <<locked>> | 90% | 55,521 psi | 83% | 3133 fps | 95.3% |
| IMR 8133 Enduron | <<locked>> | 84% | 34,635 psi | 52% | 2815 fps | 95.5% |
| Lovex S071 | <<locked>> | 80% | 41,089 psi | 62% | 2874 fps | 99.8% |
| Norma 217 | <<locked>> | 80% | 30,356 psi | 46% | 2710 fps | 95.9% |
| Norma MRP | <<locked>> | 80% | 51,155 psi | 77% | 3173 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 46,499 psi | 70% | 3091 fps | 99.1% |
| Ramshot Magnum | <<locked>> | 80% | 41,989 psi | 63% | 2953 fps | 99.4% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,269 psi | 44% | 1949 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 39,494 psi | 59% | 2992 fps | 99.7% |
| ReloadSwiss RS 80 | <<locked>> | 82% | 39,378 psi | 59% | 2943 fps | 96% |
| Rottweil R 904 | <<locked>> | 80% | 52,199 psi | 78% | 3120 fps | 99.6% |
| Rottweil R 905 | <<locked>> | 80% | 51,285 psi | 77% | 3133 fps | 99.9% |
| SNPE Vectan SP 13 | <<locked>> | 98% | 48,834 psi | 73% | 3084 fps | 96% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 50,937 psi | 76% | 3127 fps | 99.9% |
| Somchem S361 | <<locked>> | 80% | 53,417 psi | 80% | 3104 fps | 99.4% |
| Somchem S385 | <<locked>> | 80% | 51,590 psi | 77% | 3097 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 45,237 psi | 68% | 2966 fps | 99.6% |
| Vihtavuori N170 | <<locked>> | 86% | 47,921 psi | 72% | 3035 fps | 95% |
| Vihtavuori N555 | <<locked>> | 80% | 51,285 psi | 77% | 3104 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 50,531 psi | 76% | 3173 fps | 99.1% |
| Vihtavuori N565 | <<locked>> | 80% | 42,366 psi | 64% | 2976 fps | 97.7% |
| Vihtavuori N568 | <<locked>> | 82% | 40,234 psi | 60% | 2959 fps | 95.6% |
| Vihtavuori N570 | 92.4 gr | 86% | 44,498 psi | 67% | 3094 fps | 95% |
| Winchester StaBALL HD | <<locked>> | 80% | 46,122 psi | 69% | 3091 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 47,819 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 52 powders for 7.21 Firebird loaded with the .283 | 140gr | Frontier PH HPBT. ADI AR 2218 delivers the highest muzzle velocity at 3,412 fps; across all powders the maximum-charge window runs from 2,123 fps to 3,412 fps. Accurate 8700 gives the best case fill at 100 %, and 52 of the 52 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 1:10.0 twist; slower twists will usually not stabilise this weight. Accurate 8700, Hodgdon TrailBoss, IMR 8133 Enduron 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 | Frontier PH HPBT 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.