Load Specifications
Load data in caliber 7.21 Firebird with .284 | 140gr | Speer TBBC bullet and 53 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are ADI AR 2218, Vihtavuori N570 and Hodgdon Retumbo.
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% | 59,625 psi | 89% | 3196 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 51,909 psi | 78% | 3159 fps | 97.3% |
| Accurate MAGPRO | <<locked>> | 86% | 60,075 psi | 90% | 3330 fps | 99.6% |
| ADI AR 2209 | <<locked>> | 84% | 60,336 psi | 90% | 3291 fps | 100% |
| ADI AR 2213 | <<locked>> | 86% | 59,466 psi | 89% | 3314 fps | 100% |
| ADI AR 2217 | <<locked>> | 94% | 59,074 psi | 89% | 3291 fps | 100% |
| ADI AR 2218 | <<locked>> | 96% | 55,840 psi | 84% | 3356 fps | 98.8% |
| ADI AR 2225 | <<locked>> | 96% | 58,871 psi | 88% | 3310 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 84% | 59,872 psi | 90% | 3278 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 86% | 59,959 psi | 90% | 3304 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 86% | 57,957 psi | 87% | 3199 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 90% | 59,146 psi | 89% | 3281 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 82% | 59,146 psi | 89% | 3291 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 94% | 58,073 psi | 87% | 3330 fps | 98.8% |
| Alliant Reloder-50 | <<locked>> | 98% | 58,392 psi | 88% | 3323 fps | 98.5% |
| Baschieri & Pellagri 109 | <<locked>> | 88% | 59,437 psi | 89% | 3264 fps | 99.1% |
| Bofors RP15 | <<locked>> | 88% | 59,306 psi | 89% | 3294 fps | 100% |
| Bofors RP30 | <<locked>> | 92% | 59,045 psi | 89% | 3304 fps | 100% |
| Bofors RP5 | <<locked>> | 86% | 59,959 psi | 90% | 3304 fps | 100% |
| Hodgdon H1000 | <<locked>> | 92% | 56,565 psi | 85% | 3251 fps | 100% |
| Hodgdon H4831 | <<locked>> | 88% | 57,972 psi | 87% | 3238 fps | 99.8% |
| Hodgdon H4831 SC | <<locked>> | 84% | 56,710 psi | 85% | 3219 fps | 99.7% |
| Hodgdon Hybrid 100V | <<locked>> | 82% | 60,365 psi | 90% | 3182 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 90% | 58,900 psi | 88% | 3386 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,884 psi | 57% | 2126 fps | 100% |
| IMR 4831 | <<locked>> | 82% | 57,348 psi | 86% | 3169 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 84% | 57,754 psi | 87% | 3209 fps | 99.8% |
| IMR 7828 SSC | <<locked>> | 84% | 57,812 psi | 87% | 3294 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 92% | 60,336 psi | 90% | 3215 fps | 96.5% |
| IMR 8133 Enduron | <<locked>> | 98% | 57,638 psi | 86% | 3294 fps | 100% |
| Lovex S071 | <<locked>> | 90% | 57,928 psi | 87% | 3169 fps | 100% |
| Norma 217 | <<locked>> | 98% | 59,321 psi | 89% | 3317 fps | 100% |
| Norma MRP | <<locked>> | 84% | 60,234 psi | 90% | 3317 fps | 100% |
| Ramshot Grand | <<locked>> | 82% | 58,059 psi | 87% | 3294 fps | 100% |
| Ramshot Magnum | <<locked>> | 86% | 59,857 psi | 90% | 3261 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,943 psi | 58% | 2175 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 90% | 60,336 psi | 90% | 3369 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 92% | 59,393 psi | 89% | 3337 fps | 99.9% |
| Rottweil R 904 | <<locked>> | 84% | 60,336 psi | 90% | 3255 fps | 100% |
| Rottweil R 905 | <<locked>> | 84% | 59,741 psi | 90% | 3271 fps | 100% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 53,664 psi | 80% | 3169 fps | 97.3% |
| SNPE Vectan Tubal 8000 | <<locked>> | 84% | 59,408 psi | 89% | 3268 fps | 100% |
| Somchem S361 | <<locked>> | 82% | 58,175 psi | 87% | 3182 fps | 99.8% |
| Somchem S385 | <<locked>> | 84% | 59,944 psi | 90% | 3232 fps | 100% |
| Vihtavuori N165 | <<locked>> | 88% | 60,321 psi | 90% | 3219 fps | 100% |
| Vihtavuori N170 | <<locked>> | 92% | 60,060 psi | 90% | 3255 fps | 97.9% |
| Vihtavuori N555 | <<locked>> | 84% | 59,727 psi | 90% | 3232 fps | 100% |
| Vihtavuori N560 | <<locked>> | 84% | 59,408 psi | 89% | 3323 fps | 99.9% |
| Vihtavuori N565 | <<locked>> | 88% | 57,058 psi | 86% | 3258 fps | 99.9% |
| Vihtavuori N568 | <<locked>> | 92% | 59,393 psi | 89% | 3337 fps | 99.7% |
| Vihtavuori N570 | <<locked>> | 92% | 56,898 psi | 85% | 3337 fps | 98.3% |
| Winchester StaBALL HD | <<locked>> | 86% | 59,567 psi | 89% | 3297 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 82% | 57,217 psi | 86% | 3189 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% | 48,675 psi | 73% | 3018 fps | 100% |
| Accurate 8700 | <<locked>> | 96% | 44,585 psi | 67% | 3015 fps | 95.2% |
| Accurate MAGPRO | <<locked>> | 80% | 48,501 psi | 73% | 3117 fps | 97.9% |
| ADI AR 2209 | <<locked>> | 80% | 52,678 psi | 79% | 3166 fps | 99.9% |
| ADI AR 2213 | <<locked>> | 80% | 48,066 psi | 72% | 3114 fps | 99.1% |
| ADI AR 2217 | <<locked>> | 80% | 35,940 psi | 54% | 2828 fps | 96.4% |
| ADI AR 2218 | 100.5 gr | 90% | 44,512 psi | 67% | 3114 fps | 95.7% |
| ADI AR 2225 | <<locked>> | 80% | 33,228 psi | 50% | 2792 fps | 98.3% |
| Alliant Reloder-19 | <<locked>> | 80% | 52,504 psi | 79% | 3153 fps | 99.9% |
| Alliant Reloder-22 | <<locked>> | 80% | 48,834 psi | 73% | 3114 fps | 99.7% |
| Alliant Reloder-23 | <<locked>> | 80% | 47,558 psi | 71% | 3031 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 41,669 psi | 62% | 2976 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 80% | 54,998 psi | 82% | 3228 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 86% | 42,830 psi | 64% | 3028 fps | 95% |
| Alliant Reloder-50 | <<locked>> | 92% | 46,572 psi | 70% | 3094 fps | 95.7% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 45,745 psi | 69% | 3009 fps | 96.4% |
| Bofors RP15 | <<locked>> | 80% | 45,455 psi | 68% | 3045 fps | 99.3% |
| Bofors RP30 | <<locked>> | 80% | 38,986 psi | 58% | 2913 fps | 97.4% |
| Bofors RP5 | <<locked>> | 80% | 48,834 psi | 73% | 3114 fps | 99.7% |
| Hodgdon H1000 | <<locked>> | 80% | 36,927 psi | 55% | 2854 fps | 97.3% |
| Hodgdon H4831 | <<locked>> | 80% | 44,469 psi | 67% | 2986 fps | 97.9% |
| Hodgdon H4831 SC | <<locked>> | 80% | 49,516 psi | 74% | 3087 fps | 98.9% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 56,652 psi | 85% | 3127 fps | 100% |
| Hodgdon Retumbo | 84.3 gr | 80% | 40,770 psi | 61% | 3038 fps | 99.3% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,543 psi | 43% | 1909 fps | 100% |
| IMR 4831 | <<locked>> | 80% | 53,853 psi | 81% | 3117 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 50,749 psi | 76% | 3087 fps | 99.2% |
| IMR 7828 SSC | <<locked>> | 80% | 50,067 psi | 75% | 3156 fps | 99.4% |
| IMR 7977 Enduron | <<locked>> | 90% | 56,637 psi | 85% | 3156 fps | 95.7% |
| IMR 8133 Enduron | <<locked>> | 84% | 35,578 psi | 53% | 2838 fps | 96% |
| Lovex S071 | <<locked>> | 80% | 41,858 psi | 63% | 2887 fps | 99.9% |
| Norma 217 | <<locked>> | 80% | 31,212 psi | 47% | 2730 fps | 96.3% |
| Norma MRP | <<locked>> | 80% | 52,257 psi | 78% | 3189 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 53,809 psi | 81% | 3225 fps | 99.9% |
| Ramshot Magnum | <<locked>> | 80% | 47,485 psi | 71% | 3058 fps | 99.9% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,283 psi | 44% | 1955 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 40,669 psi | 61% | 3012 fps | 99.8% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 37,420 psi | 56% | 2887 fps | 95.2% |
| Rottweil R 904 | <<locked>> | 80% | 53,055 psi | 80% | 3133 fps | 99.7% |
| Rottweil R 905 | <<locked>> | 80% | 52,388 psi | 79% | 3150 fps | 100% |
| SNPE Vectan SP 13 | <<locked>> | 96% | 46,775 psi | 70% | 3038 fps | 95.4% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 52,040 psi | 78% | 3146 fps | 99.9% |
| Somchem S361 | <<locked>> | 80% | 54,433 psi | 82% | 3120 fps | 99.5% |
| Somchem S385 | <<locked>> | 80% | 52,605 psi | 79% | 3114 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 46,238 psi | 69% | 2986 fps | 99.7% |
| Vihtavuori N170 | <<locked>> | 86% | 48,878 psi | 73% | 3054 fps | 95.4% |
| Vihtavuori N555 | <<locked>> | 80% | 52,431 psi | 79% | 3117 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 51,619 psi | 77% | 3189 fps | 99.3% |
| Vihtavuori N565 | <<locked>> | 80% | 43,366 psi | 65% | 2992 fps | 98% |
| Vihtavuori N568 | <<locked>> | 80% | 38,406 psi | 58% | 2910 fps | 95% |
| Vihtavuori N570 | 94.1 gr | 86% | 45,658 psi | 68% | 3114 fps | 95.5% |
| Winchester StaBALL HD | <<locked>> | 80% | 47,442 psi | 71% | 3107 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 53,287 psi | 80% | 3123 fps | 100% |
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 53 powders for 7.21 Firebird loaded with the .284 | 140gr | Speer TBBC. Hodgdon Retumbo delivers the highest muzzle velocity at 3,386 fps; across all powders the maximum-charge window runs from 2,126 fps to 3,386 fps. Accurate 8700 gives the best case fill at 100 %, and 53 of the 53 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 0.284" calls for a 1:12.0 twist; slower twists will usually not stabilise this weight. Accurate 8700, Hodgdon TrailBoss, ReloadSwiss RS 14 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. ADI AR 2218, Vihtavuori N570, Hodgdon Retumbo rank at the top here: for 7.21 Firebird with the .284 | 140gr | Speer TBBC 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.