Load Specifications
Load data in caliber 7.21 Firebird with .284 | 120gr | Sierra Pro-Hunter bullet and 51 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Vihtavuori N570, Hodgdon Retumbo 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.
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Max Load - Barrel Length: 26"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 3100 | <<locked>> | 88% | 59,828 psi | 90% | 3386 fps | 100% |
| Accurate MAGPRO | <<locked>> | 86% | 59,074 psi | 89% | 3504 fps | 99.2% |
| ADI AR 2209 | <<locked>> | 84% | 56,811 psi | 85% | 3428 fps | 99.9% |
| ADI AR 2213 | <<locked>> | 88% | 59,698 psi | 89% | 3507 fps | 99.7% |
| ADI AR 2217 | <<locked>> | 96% | 59,030 psi | 88% | 3474 fps | 99.9% |
| ADI AR 2218 | <<locked>> | 98% | 55,941 psi | 84% | 3520 fps | 97.7% |
| ADI AR 2225 | <<locked>> | 98% | 58,566 psi | 88% | 3497 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 86% | 60,336 psi | 90% | 3481 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 88% | 60,118 psi | 90% | 3501 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 88% | 57,899 psi | 87% | 3392 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 92% | 58,871 psi | 88% | 3471 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 84% | 59,248 psi | 89% | 3491 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 96% | 57,972 psi | 87% | 3497 fps | 97.8% |
| Alliant Reloder-50ᴾ | <<locked>> | 100% | 58,262 psi | 87% | 3484 fps | 97.4% |
| Baschieri & Pellagri 109 | <<locked>> | 90% | 60,046 psi | 90% | 3448 fps | 98.3% |
| Bofors RP15 | <<locked>> | 90% | 59,321 psi | 89% | 3484 fps | 100% |
| Bofors RP30 | <<locked>> | 94% | 58,798 psi | 88% | 3488 fps | 99.9% |
| Bofors RP5 | <<locked>> | 88% | 60,118 psi | 90% | 3501 fps | 100% |
| Hodgdon H1000 | <<locked>> | 92% | 56,260 psi | 84% | 3432 fps | 99.9% |
| Hodgdon H4831 | <<locked>> | 86% | 58,349 psi | 87% | 3428 fps | 99.3% |
| Hodgdon H4831 SC | <<locked>> | 86% | 57,246 psi | 86% | 3412 fps | 99.2% |
| Hodgdon Hybrid 100V | <<locked>> | 82% | 56,855 psi | 85% | 3330 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 92% | 58,305 psi | 87% | 3570 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,724 psi | 57% | 2283 fps | 100% |
| IMR 4350 | <<locked>> | 82% | 58,624 psi | 88% | 3399 fps | 100% |
| IMR 4831 | <<locked>> | 82% | 59,625 psi | 89% | 3402 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 86% | 58,262 psi | 87% | 3402 fps | 99.4% |
| IMR 7828 SSC | <<locked>> | 88% | 57,943 psi | 87% | 3484 fps | 99.6% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 57,334 psi | 86% | 3471 fps | 99.8% |
| Lovex S071 | <<locked>> | 92% | 57,769 psi | 87% | 3360 fps | 100% |
| Norma 217ᴾ | <<locked>> | 100% | 58,769 psi | 88% | 3497 fps | 100% |
| Norma MRP | <<locked>> | 84% | 56,202 psi | 84% | 3448 fps | 100% |
| Ramshot Grand | <<locked>> | 88% | 59,596 psi | 89% | 3510 fps | 99.9% |
| Ramshot Magnum | <<locked>> | 90% | 58,378 psi | 88% | 3425 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,696 psi | 58% | 2336 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 92% | 60,075 psi | 90% | 3556 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 94% | 59,306 psi | 89% | 3514 fps | 99.4% |
| Rottweil R 904 | <<locked>> | 84% | 57,130 psi | 86% | 3392 fps | 99.5% |
| Rottweil R 905 | <<locked>> | 86% | 60,002 psi | 90% | 3468 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 86% | 59,611 psi | 89% | 3465 fps | 100% |
| Somchem S361 | <<locked>> | 84% | 58,856 psi | 88% | 3376 fps | 99.4% |
| Somchem S365 | <<locked>> | 82% | 59,248 psi | 89% | 3392 fps | 100% |
| Somchem S385 | <<locked>> | 84% | 56,637 psi | 85% | 3369 fps | 100% |
| Vihtavuori N165 | <<locked>> | 88% | 56,681 psi | 85% | 3350 fps | 100% |
| Vihtavuori N555 | <<locked>> | 86% | 59,683 psi | 89% | 3428 fps | 100% |
| Vihtavuori N560 | <<locked>> | 86% | 59,698 psi | 89% | 3520 fps | 99.5% |
| Vihtavuori N565 | <<locked>> | 90% | 57,159 psi | 86% | 3438 fps | 99.4% |
| Vihtavuori N568 | <<locked>> | 94% | 59,263 psi | 89% | 3510 fps | 99% |
| Vihtavuori N570 | <<locked>> | 94% | 56,652 psi | 85% | 3507 fps | 97.1% |
| Winchester StaBALL HD | <<locked>> | 88% | 59,059 psi | 89% | 3491 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 86% | 56,579 psi | 85% | 3363 fps | 99.9% |
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% | 45,397 psi | 68% | 3136 fps | 99.8% |
| Accurate MAGPRO | <<locked>> | 80% | 47,558 psi | 71% | 3278 fps | 96.9% |
| ADI AR 2209 | <<locked>> | 80% | 49,516 psi | 74% | 3291 fps | 99.2% |
| ADI AR 2213 | <<locked>> | 80% | 44,788 psi | 67% | 3215 fps | 97.3% |
| ADI AR 2217 | <<locked>> | 84% | 38,377 psi | 58% | 3048 fps | 95.7% |
| ADI AR 2218 | <<locked>> | 94% | 48,022 psi | 72% | 3346 fps | 95.2% |
| ADI AR 2225 | <<locked>> | 80% | 30,719 psi | 46% | 2858 fps | 95.2% |
| Alliant Reloder-19 | <<locked>> | 80% | 49,298 psi | 74% | 3278 fps | 99.1% |
| Alliant Reloder-22 | <<locked>> | 80% | 45,614 psi | 68% | 3225 fps | 98.6% |
| Alliant Reloder-23 | <<locked>> | 80% | 44,295 psi | 66% | 3156 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 38,493 psi | 58% | 3077 fps | 99.4% |
| Alliant Reloder-26 | <<locked>> | 80% | 50,966 psi | 76% | 3350 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 92% | 49,690 psi | 74% | 3337 fps | 95.7% |
| Alliant Reloder-50 | <<locked>> | 96% | 49,893 psi | 75% | 3320 fps | 95.2% |
| Baschieri & Pellagri 109 | <<locked>> | 82% | 45,948 psi | 69% | 3176 fps | 95% |
| Bofors RP15 | <<locked>> | 80% | 42,366 psi | 64% | 3146 fps | 97.7% |
| Bofors RP30 | <<locked>> | 82% | 38,595 psi | 58% | 3061 fps | 95.8% |
| Bofors RP5 | <<locked>> | 80% | 45,614 psi | 68% | 3225 fps | 98.6% |
| Hodgdon H1000 | <<locked>> | 80% | 36,318 psi | 54% | 2995 fps | 95.5% |
| Hodgdon H4831 | <<locked>> | 80% | 47,384 psi | 71% | 3219 fps | 97.4% |
| Hodgdon H4831 SC | <<locked>> | 80% | 46,485 psi | 70% | 3199 fps | 97.2% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 53,214 psi | 80% | 3271 fps | 100% |
| Hodgdon Retumbo | 87.3 gr | 80% | 37,536 psi | 56% | 3117 fps | 97.1% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,326 psi | 42% | 2054 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 55,056 psi | 83% | 3337 fps | 100% |
| IMR 4831 | <<locked>> | 80% | 55,912 psi | 84% | 3343 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 48,066 psi | 72% | 3209 fps | 97.8% |
| IMR 7828 SSC | <<locked>> | 80% | 43,497 psi | 65% | 3192 fps | 97% |
| IMR 8133 Enduron | <<locked>> | 88% | 37,521 psi | 56% | 3045 fps | 95.2% |
| Lovex S071 | <<locked>> | 80% | 39,030 psi | 59% | 2992 fps | 98.9% |
| Norma 217 | <<locked>> | 84% | 32,924 psi | 49% | 2933 fps | 95.5% |
| Norma MRP | <<locked>> | 80% | 48,660 psi | 73% | 3304 fps | 99.7% |
| Ramshot Grand | <<locked>> | 80% | 43,990 psi | 66% | 3209 fps | 97.5% |
| Ramshot Magnum | <<locked>> | 80% | 39,784 psi | 60% | 3064 fps | 98% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 28,979 psi | 43% | 2100 fps | 100% |
| ReloadSwiss RS 76 | 93.4 gr | 80% | 37,188 psi | 56% | 3087 fps | 98.2% |
| ReloadSwiss RS 80 | <<locked>> | 86% | 43,453 psi | 65% | 3196 fps | 96% |
| Rottweil R 904 | <<locked>> | 80% | 50,038 psi | 75% | 3258 fps | 98.5% |
| Rottweil R 905 | <<locked>> | 80% | 49,052 psi | 74% | 3271 fps | 99.2% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 48,704 psi | 73% | 3264 fps | 99.1% |
| Somchem S361 | <<locked>> | 80% | 51,372 psi | 77% | 3241 fps | 98.3% |
| Somchem S365 | <<locked>> | 80% | 55,463 psi | 83% | 3337 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 49,487 psi | 74% | 3238 fps | 99.6% |
| Vihtavuori N165 | <<locked>> | 80% | 43,221 psi | 65% | 3091 fps | 98.5% |
| Vihtavuori N555 | <<locked>> | 80% | 48,878 psi | 73% | 3245 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 48,167 psi | 72% | 3297 fps | 97.7% |
| Vihtavuori N565 | <<locked>> | 80% | 40,176 psi | 60% | 3081 fps | 95.5% |
| Vihtavuori N568 | <<locked>> | 86% | 44,164 psi | 66% | 3209 fps | 95.6% |
| Vihtavuori N570 | 104.2 gr | 92% | 52,533 psi | 79% | 3428 fps | 96.1% |
| Winchester StaBALL HD | <<locked>> | 80% | 43,337 psi | 65% | 3219 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 45,701 psi | 69% | 3156 fps | 98.6% |
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 51 powders for 7.21 Firebird loaded with the .284 | 120gr | Sierra Pro-Hunter. Hodgdon Retumbo delivers the highest muzzle velocity at 3,570 fps; across all powders the maximum-charge window runs from 2,283 fps to 3,570 fps. Alliant Reloder-50 gives the best case fill at 100 %, and 51 of the 51 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 120.0 gr projectile in 0.284" calls for a 1:16.0 twist; slower twists will usually not stabilise this weight. Alliant Reloder-50, 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. Vihtavuori N570, Hodgdon Retumbo, ReloadSwiss RS 76 rank at the top here: for 7.21 Firebird with the .284 | 120gr | Sierra Pro-Hunter 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.