Load Specifications
Load data in caliber 7.21 Firebird with .284 | 130gr | NorthFork Bonded Core 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>> | 86% | 56,724 psi | 85% | 3245 fps | 100% |
| Accurate MAGPRO | <<locked>> | 86% | 60,017 psi | 90% | 3428 fps | 99.5% |
| ADI AR 2209 | <<locked>> | 84% | 57,522 psi | 86% | 3343 fps | 100% |
| ADI AR 2213 | <<locked>> | 86% | 56,405 psi | 85% | 3356 fps | 99.7% |
| ADI AR 2217 | <<locked>> | 96% | 59,843 psi | 90% | 3396 fps | 100% |
| ADI AR 2218 | <<locked>> | 98% | 56,739 psi | 85% | 3455 fps | 98.4% |
| ADI AR 2225 | <<locked>> | 98% | 59,466 psi | 89% | 3419 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 84% | 57,145 psi | 86% | 3327 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 86% | 56,927 psi | 85% | 3350 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 88% | 58,871 psi | 88% | 3307 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 92% | 59,843 psi | 90% | 3389 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 84% | 60,191 psi | 90% | 3406 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 96% | 58,987 psi | 88% | 3432 fps | 98.5% |
| Alliant Reloder-50ᴾ | <<locked>> | 100% | 59,176 psi | 89% | 3422 fps | 98.1% |
| Baschieri & Pellagri 109 | <<locked>> | 88% | 56,840 psi | 85% | 3304 fps | 98.2% |
| Bofors RP15 | <<locked>> | 90% | 60,220 psi | 90% | 3402 fps | 100% |
| Bofors RP30 | <<locked>> | 94% | 59,683 psi | 89% | 3409 fps | 100% |
| Bofors RP5 | <<locked>> | 86% | 56,927 psi | 85% | 3350 fps | 100% |
| Hodgdon H1000 | <<locked>> | 92% | 57,319 psi | 86% | 3356 fps | 100% |
| Hodgdon H4831 | <<locked>> | 86% | 59,117 psi | 89% | 3346 fps | 99.6% |
| Hodgdon H4831 SC | <<locked>> | 86% | 58,001 psi | 87% | 3327 fps | 99.5% |
| Hodgdon Hybrid 100V | <<locked>> | 82% | 57,667 psi | 86% | 3241 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 92% | 59,277 psi | 89% | 3491 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,840 psi | 57% | 2198 fps | 100% |
| IMR 4350 | <<locked>> | 82% | 59,509 psi | 89% | 3314 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 86% | 59,001 psi | 88% | 3320 fps | 99.7% |
| IMR 7828 SSC | <<locked>> | 88% | 58,871 psi | 88% | 3406 fps | 99.9% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 58,102 psi | 87% | 3396 fps | 99.9% |
| Lovex S071 | <<locked>> | 92% | 58,769 psi | 88% | 3274 fps | 100% |
| Norma 217ᴾ | <<locked>> | 100% | 59,669 psi | 89% | 3419 fps | 100% |
| Norma MRP | <<locked>> | 84% | 57,246 psi | 86% | 3369 fps | 100% |
| Ramshot Grand | <<locked>> | 86% | 56,376 psi | 85% | 3363 fps | 99.8% |
| Ramshot Magnum | <<locked>> | 90% | 59,422 psi | 89% | 3346 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,725 psi | 58% | 2244 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 90% | 56,362 psi | 84% | 3406 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 94% | 60,220 psi | 90% | 3438 fps | 99.7% |
| Rottweil R 904 | <<locked>> | 84% | 57,943 psi | 87% | 3310 fps | 99.8% |
| Rottweil R 905 | <<locked>> | 84% | 57,101 psi | 86% | 3323 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 84% | 56,724 psi | 85% | 3320 fps | 100% |
| Somchem S361 | <<locked>> | 84% | 59,683 psi | 89% | 3294 fps | 99.7% |
| Somchem S365 | <<locked>> | 82% | 60,292 psi | 90% | 3304 fps | 100% |
| Somchem S385 | <<locked>> | 84% | 57,406 psi | 86% | 3287 fps | 100% |
| Vihtavuori N165 | <<locked>> | 88% | 57,479 psi | 86% | 3271 fps | 100% |
| Vihtavuori N170 | <<locked>> | 92% | 57,087 psi | 86% | 3291 fps | 96.7% |
| Vihtavuori N555 | <<locked>> | 84% | 56,797 psi | 85% | 3284 fps | 100% |
| Vihtavuori N560 | <<locked>> | 84% | 56,550 psi | 85% | 3369 fps | 99.5% |
| Vihtavuori N565 | <<locked>> | 90% | 57,972 psi | 87% | 3363 fps | 99.7% |
| Vihtavuori N568 | <<locked>> | 94% | 60,133 psi | 90% | 3438 fps | 99.4% |
| Vihtavuori N570 | <<locked>> | 94% | 57,479 psi | 86% | 3438 fps | 97.8% |
| Winchester StaBALL HD | <<locked>> | 88% | 60,205 psi | 90% | 3409 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 86% | 57,363 psi | 86% | 3281 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% | 46,180 psi | 69% | 3061 fps | 100% |
| Accurate MAGPRO | <<locked>> | 80% | 48,341 psi | 72% | 3209 fps | 97.7% |
| ADI AR 2209 | <<locked>> | 80% | 50,299 psi | 75% | 3212 fps | 99.6% |
| ADI AR 2213 | <<locked>> | 80% | 45,498 psi | 68% | 3143 fps | 98.1% |
| ADI AR 2217 | <<locked>> | 82% | 36,405 psi | 55% | 2917 fps | 95.7% |
| ADI AR 2218 | <<locked>> | 94% | 48,675 psi | 73% | 3284 fps | 96.3% |
| ADI AR 2225 | <<locked>> | 80% | 31,328 psi | 47% | 2808 fps | 96.6% |
| Alliant Reloder-19 | <<locked>> | 80% | 50,067 psi | 75% | 3202 fps | 99.5% |
| Alliant Reloder-22 | <<locked>> | 80% | 46,282 psi | 69% | 3150 fps | 99.1% |
| Alliant Reloder-23 | <<locked>> | 80% | 45,020 psi | 67% | 3081 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 39,262 psi | 59% | 3012 fps | 99.8% |
| Alliant Reloder-26 | <<locked>> | 80% | 51,779 psi | 78% | 3271 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 90% | 46,775 psi | 70% | 3196 fps | 95.5% |
| Alliant Reloder-50 | <<locked>> | 94% | 47,065 psi | 71% | 3186 fps | 95% |
| Baschieri & Pellagri 109 | <<locked>> | 82% | 46,630 psi | 70% | 3107 fps | 95.8% |
| Bofors RP15 | <<locked>> | 80% | 43,076 psi | 65% | 3077 fps | 98.4% |
| Bofors RP30 | <<locked>> | 80% | 36,637 psi | 55% | 2933 fps | 95.8% |
| Bofors RP5 | <<locked>> | 80% | 46,282 psi | 69% | 3150 fps | 99.1% |
| Hodgdon H1000 | <<locked>> | 80% | 36,927 psi | 55% | 2933 fps | 96.5% |
| Hodgdon H4831 | <<locked>> | 80% | 48,051 psi | 72% | 3143 fps | 98.1% |
| Hodgdon H4831 SC | <<locked>> | 80% | 47,123 psi | 71% | 3127 fps | 97.9% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 54,041 psi | 81% | 3186 fps | 100% |
| Hodgdon Retumbo | 84.4 gr | 80% | 38,348 psi | 57% | 3058 fps | 98.1% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,384 psi | 43% | 1972 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 55,796 psi | 84% | 3255 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 48,733 psi | 73% | 3130 fps | 98.4% |
| IMR 7828 SSC | <<locked>> | 80% | 44,309 psi | 66% | 3127 fps | 97.8% |
| IMR 8133 Enduron | <<locked>> | 86% | 35,766 psi | 54% | 2920 fps | 95.2% |
| Lovex S071 | <<locked>> | 80% | 39,798 psi | 60% | 2927 fps | 99.4% |
| Norma 217 | <<locked>> | 82% | 31,256 psi | 47% | 2808 fps | 95.5% |
| Norma MRP | <<locked>> | 80% | 49,559 psi | 74% | 3232 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 44,744 psi | 67% | 3140 fps | 98.3% |
| Ramshot Magnum | <<locked>> | 80% | 40,538 psi | 61% | 2999 fps | 98.7% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,080 psi | 44% | 2018 fps | 100% |
| ReloadSwiss RS 76 | 90.3 gr | 80% | 37,956 psi | 57% | 3028 fps | 99% |
| ReloadSwiss RS 80 | <<locked>> | 84% | 40,886 psi | 61% | 3054 fps | 95.8% |
| Rottweil R 904 | <<locked>> | 80% | 50,705 psi | 76% | 3179 fps | 99.1% |
| Rottweil R 905 | <<locked>> | 80% | 49,821 psi | 75% | 3192 fps | 99.6% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 49,472 psi | 74% | 3186 fps | 99.5% |
| Somchem S361 | <<locked>> | 80% | 52,054 psi | 78% | 3166 fps | 98.9% |
| Somchem S365 | <<locked>> | 80% | 56,347 psi | 84% | 3251 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 50,154 psi | 75% | 3159 fps | 99.9% |
| Vihtavuori N165 | <<locked>> | 80% | 43,932 psi | 66% | 3022 fps | 99.1% |
| Vihtavuori N170 | <<locked>> | 90% | 53,287 psi | 80% | 3219 fps | 95.8% |
| Vihtavuori N555 | <<locked>> | 80% | 49,777 psi | 75% | 3166 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 49,037 psi | 74% | 3228 fps | 98.4% |
| Vihtavuori N565 | <<locked>> | 80% | 40,915 psi | 61% | 3018 fps | 96.6% |
| Vihtavuori N568 | <<locked>> | 84% | 41,742 psi | 63% | 3074 fps | 95.4% |
| Vihtavuori N570 | 98.5 gr | 90% | 49,588 psi | 74% | 3284 fps | 95.9% |
| Winchester StaBALL HD | <<locked>> | 80% | 44,309 psi | 66% | 3146 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 46,398 psi | 70% | 3084 fps | 99.1% |
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 | 130gr | NorthFork Bonded Core. Hodgdon Retumbo delivers the highest muzzle velocity at 3,491 fps; across all powders the maximum-charge window runs from 2,198 fps to 3,491 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 130.0 gr projectile in 0.284" calls for a 1:12.0 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 | 130gr | NorthFork Bonded Core 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.