Load Specifications
Load data in caliber 7.21 Firebird with .284 | 139gr | Sellier & Bellot SPRN bullet and 50 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 ReloadSwiss RS 76.
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.
A valid access license is required to use the Personalized Load Calculator.
You can find more information in our FAQ: How can I use the Personalized Load Calculator?
Max Load - Barrel Length: 26"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 3100 | <<locked>> | 84% | 56,637 psi | 85% | 3159 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 53,272 psi | 80% | 3186 fps | 97.6% |
| Accurate MAGPRO | <<locked>> | 84% | 60,046 psi | 90% | 3340 fps | 99.8% |
| ADI AR 2209 | <<locked>> | 82% | 57,305 psi | 86% | 3251 fps | 100% |
| ADI AR 2213 | <<locked>> | 84% | 56,376 psi | 85% | 3271 fps | 99.9% |
| ADI AR 2217 | <<locked>> | 92% | 56,159 psi | 84% | 3251 fps | 100% |
| ADI AR 2218 | <<locked>> | 96% | 57,348 psi | 86% | 3389 fps | 99.1% |
| ADI AR 2225 | <<locked>> | 94% | 56,202 psi | 84% | 3278 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 82% | 56,985 psi | 85% | 3241 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 84% | 56,956 psi | 85% | 3264 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 86% | 59,103 psi | 89% | 3219 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 90% | 60,234 psi | 90% | 3304 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 94% | 59,596 psi | 89% | 3363 fps | 99% |
| Alliant Reloder-50 | <<locked>> | 98% | 60,118 psi | 90% | 3353 fps | 98.8% |
| Baschieri & Pellagri 109 | <<locked>> | 88% | 60,365 psi | 90% | 3284 fps | 99.2% |
| Bofors RP15 | <<locked>> | 88% | 60,321 psi | 90% | 3317 fps | 100% |
| Bofors RP30 | <<locked>> | 92% | 60,205 psi | 90% | 3330 fps | 100% |
| Bofors RP5 | <<locked>> | 84% | 56,956 psi | 85% | 3264 fps | 100% |
| Hodgdon H1000 | <<locked>> | 90% | 57,595 psi | 86% | 3271 fps | 100% |
| Hodgdon H4831 | <<locked>> | 84% | 58,798 psi | 88% | 3261 fps | 99.9% |
| Hodgdon H4831 SC | <<locked>> | 84% | 57,711 psi | 87% | 3241 fps | 99.8% |
| Hodgdon Retumbo | <<locked>> | 90% | 60,292 psi | 90% | 3409 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,014 psi | 57% | 2142 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 84% | 58,697 psi | 88% | 3232 fps | 99.9% |
| IMR 7828 SSC | <<locked>> | 86% | 59,103 psi | 89% | 3320 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 90% | 57,450 psi | 86% | 3179 fps | 96% |
| IMR 8133 Enduron | <<locked>> | 98% | 59,132 psi | 89% | 3323 fps | 100% |
| Lovex S071 | <<locked>> | 90% | 58,784 psi | 88% | 3192 fps | 100% |
| Norma 217 | <<locked>> | 96% | 56,666 psi | 85% | 3281 fps | 100% |
| Norma MRP | <<locked>> | 82% | 57,217 psi | 86% | 3278 fps | 100% |
| Ramshot Grand | <<locked>> | 84% | 56,637 psi | 85% | 3278 fps | 100% |
| Ramshot Magnum | <<locked>> | 88% | 59,596 psi | 89% | 3264 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,044 psi | 59% | 2192 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 88% | 57,159 psi | 86% | 3320 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 90% | 56,260 psi | 84% | 3287 fps | 99.7% |
| Rottweil R 904 | <<locked>> | 82% | 57,551 psi | 86% | 3219 fps | 99.9% |
| Rottweil R 905 | <<locked>> | 82% | 56,826 psi | 85% | 3232 fps | 100% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 55,027 psi | 82% | 3199 fps | 97.6% |
| SNPE Vectan Tubal 8000 | <<locked>> | 82% | 56,463 psi | 85% | 3228 fps | 100% |
| Somchem S361 | <<locked>> | 82% | 59,016 psi | 88% | 3205 fps | 99.9% |
| Somchem S385 | <<locked>> | 82% | 57,217 psi | 86% | 3199 fps | 100% |
| Vihtavuori N165 | <<locked>> | 86% | 57,450 psi | 86% | 3186 fps | 100% |
| Vihtavuori N170 | <<locked>> | 90% | 57,203 psi | 86% | 3215 fps | 97.4% |
| Vihtavuori N555 | <<locked>> | 82% | 56,927 psi | 85% | 3196 fps | 100% |
| Vihtavuori N560 | <<locked>> | 82% | 56,434 psi | 85% | 3281 fps | 99.8% |
| Vihtavuori N565 | <<locked>> | 88% | 58,204 psi | 87% | 3281 fps | 99.9% |
| Vihtavuori N568 | <<locked>> | 90% | 56,550 psi | 85% | 3294 fps | 99.4% |
| Vihtavuori N570 | <<locked>> | 92% | 58,233 psi | 87% | 3366 fps | 98.5% |
| Winchester StaBALL HD | <<locked>> | 84% | 56,681 psi | 85% | 3261 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 84% | 57,087 psi | 86% | 3196 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% | 49,574 psi | 74% | 3045 fps | 100% |
| Accurate 8700 | <<locked>> | 96% | 45,905 psi | 69% | 3045 fps | 95.6% |
| Accurate MAGPRO | <<locked>> | 80% | 52,156 psi | 78% | 3202 fps | 99% |
| ADI AR 2209 | <<locked>> | 80% | 53,635 psi | 80% | 3192 fps | 100% |
| ADI AR 2213 | <<locked>> | 80% | 49,008 psi | 73% | 3136 fps | 99.2% |
| ADI AR 2217 | <<locked>> | 80% | 36,579 psi | 55% | 2851 fps | 96.6% |
| ADI AR 2218 | 102.7 gr | 90% | 45,687 psi | 68% | 3143 fps | 96.2% |
| ADI AR 2225 | <<locked>> | 80% | 33,968 psi | 51% | 2815 fps | 98.5% |
| Alliant Reloder-19 | <<locked>> | 80% | 53,403 psi | 80% | 3179 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 49,763 psi | 75% | 3136 fps | 99.8% |
| Alliant Reloder-23 | <<locked>> | 80% | 48,414 psi | 73% | 3054 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 42,627 psi | 64% | 3002 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 86% | 43,976 psi | 66% | 3054 fps | 95.4% |
| Alliant Reloder-50 | <<locked>> | 92% | 47,834 psi | 72% | 3123 fps | 96.1% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 46,398 psi | 70% | 3028 fps | 96.6% |
| Bofors RP15 | <<locked>> | 80% | 46,224 psi | 69% | 3064 fps | 99.4% |
| Bofors RP30 | <<locked>> | 80% | 39,856 psi | 60% | 2936 fps | 97.7% |
| Bofors RP5 | <<locked>> | 80% | 49,763 psi | 75% | 3136 fps | 99.8% |
| Hodgdon H1000 | <<locked>> | 80% | 39,958 psi | 60% | 2936 fps | 98.3% |
| Hodgdon H4831 | <<locked>> | 80% | 51,343 psi | 77% | 3130 fps | 99.2% |
| Hodgdon H4831 SC | <<locked>> | 80% | 50,357 psi | 75% | 3110 fps | 99% |
| Hodgdon Retumbo | 86.1 gr | 80% | 41,698 psi | 63% | 3064 fps | 99.5% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,587 psi | 43% | 1923 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 51,561 psi | 77% | 3110 fps | 99.3% |
| IMR 7828 SSC | <<locked>> | 80% | 47,732 psi | 72% | 3114 fps | 99.1% |
| IMR 7977 Enduron | <<locked>> | 88% | 53,824 psi | 81% | 3114 fps | 95.1% |
| IMR 8133 Enduron | <<locked>> | 82% | 33,895 psi | 51% | 2792 fps | 95.2% |
| Lovex S071 | <<locked>> | 80% | 42,641 psi | 64% | 2910 fps | 99.9% |
| Norma 217 | <<locked>> | 80% | 32,082 psi | 48% | 2753 fps | 96.7% |
| Norma MRP | <<locked>> | 80% | 53,359 psi | 80% | 3215 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 48,602 psi | 73% | 3136 fps | 99.4% |
| Ramshot Magnum | <<locked>> | 80% | 43,990 psi | 66% | 2995 fps | 99.7% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,312 psi | 44% | 1969 fps | 100% |
| ReloadSwiss RS 76 | 92.2 gr | 80% | 41,684 psi | 62% | 3038 fps | 99.9% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 38,334 psi | 57% | 2913 fps | 95.6% |
| Rottweil R 904 | <<locked>> | 80% | 53,940 psi | 81% | 3159 fps | 99.8% |
| Rottweil R 905 | <<locked>> | 80% | 53,156 psi | 80% | 3169 fps | 100% |
| SNPE Vectan SP 13 | <<locked>> | 96% | 47,790 psi | 72% | 3061 fps | 95.8% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 52,808 psi | 79% | 3166 fps | 100% |
| Somchem S361 | <<locked>> | 80% | 55,143 psi | 83% | 3143 fps | 99.6% |
| Somchem S385 | <<locked>> | 80% | 53,505 psi | 80% | 3136 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 47,065 psi | 71% | 3005 fps | 99.8% |
| Vihtavuori N170 | <<locked>> | 86% | 49,835 psi | 75% | 3077 fps | 95.7% |
| Vihtavuori N555 | <<locked>> | 80% | 53,316 psi | 80% | 3140 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 52,678 psi | 79% | 3215 fps | 99.4% |
| Vihtavuori N565 | <<locked>> | 80% | 44,193 psi | 66% | 3015 fps | 98.2% |
| Vihtavuori N568 | <<locked>> | 80% | 39,320 psi | 59% | 2936 fps | 95.3% |
| Vihtavuori N570 | <<locked>> | 86% | 46,746 psi | 70% | 3143 fps | 95.8% |
| Winchester StaBALL HD | <<locked>> | 80% | 48,747 psi | 73% | 3133 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 49,632 psi | 74% | 3068 fps | 99.8% |
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 50 powders for 7.21 Firebird loaded with the .284 | 139gr | Sellier & Bellot SPRN. Hodgdon Retumbo delivers the highest muzzle velocity at 3,409 fps; across all powders the maximum-charge window runs from 2,142 fps to 3,409 fps. Accurate 8700 gives the best case fill at 100 %, and 50 of the 50 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 139.0 gr projectile in 0.284" calls for a 1:15.0 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. Hodgdon Retumbo, ADI AR 2218, ReloadSwiss RS 76 rank at the top here: for 7.21 Firebird with the .284 | 139gr | Sellier & Bellot SPRN 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.