Load Specifications
Load data in caliber 7.21 Firebird with .284 | 127gr | Geco ZERO LG bullet and 66 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>> | 90% | 59,886 psi | 90% | 3330 fps | 100% |
| Accurate 4350 | <<locked>> | 82% | 59,901 psi | 90% | 3356 fps | 100% |
| Accurate MAGPRO | <<locked>> | 88% | 59,350 psi | 89% | 3448 fps | 99.3% |
| ADI AR 2209 | <<locked>> | 86% | 57,435 psi | 86% | 3373 fps | 99.9% |
| ADI AR 2213 | <<locked>> | 90% | 60,133 psi | 90% | 3451 fps | 99.8% |
| ADI AR 2217 | <<locked>> | 98% | 59,117 psi | 89% | 3419 fps | 99.9% |
| ADI AR 2218ᴾ | <<locked>> | 100% | 55,854 psi | 84% | 3468 fps | 97.8% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 57,899 psi | 87% | 3435 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 82% | 57,479 psi | 86% | 3366 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 86% | 57,014 psi | 85% | 3360 fps | 99.9% |
| Alliant Reloder-22 | <<locked>> | 90% | 60,336 psi | 90% | 3442 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 90% | 58,218 psi | 87% | 3337 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 94% | 58,914 psi | 88% | 3415 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 86% | 59,321 psi | 89% | 3432 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 98% | 57,638 psi | 86% | 3442 fps | 97.9% |
| Alliant Reloder-50ᴾ | <<locked>> | 100% | 52,953 psi | 79% | 3340 fps | 96.4% |
| Baschieri & Pellagri 109 | <<locked>> | 90% | 56,869 psi | 85% | 3333 fps | 97.9% |
| Bofors RP15 | <<locked>> | 92% | 59,640 psi | 89% | 3428 fps | 100% |
| Bofors RP30 | <<locked>> | 96% | 58,552 psi | 88% | 3428 fps | 99.9% |
| Bofors RP5 | <<locked>> | 90% | 60,336 psi | 90% | 3442 fps | 100% |
| Hodgdon H1000 | <<locked>> | 94% | 56,405 psi | 85% | 3376 fps | 99.9% |
| Hodgdon H4831 | <<locked>> | 88% | 59,088 psi | 89% | 3376 fps | 99.4% |
| Hodgdon H4831 SC | <<locked>> | 88% | 57,885 psi | 87% | 3356 fps | 99.3% |
| Hodgdon Hybrid 100V | <<locked>> | 84% | 57,522 psi | 86% | 3274 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 94% | 58,001 psi | 87% | 3510 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,536 psi | 56% | 2205 fps | 100% |
| IMR 4350 | <<locked>> | 84% | 59,582 psi | 89% | 3346 fps | 100% |
| IMR 4831 | <<locked>> | 84% | 60,263 psi | 90% | 3346 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 88% | 59,088 psi | 89% | 3353 fps | 99.5% |
| IMR 7828 SSC | <<locked>> | 90% | 58,291 psi | 87% | 3428 fps | 99.7% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 52,823 psi | 79% | 3340 fps | 99.4% |
| Lovex S065 | <<locked>> | 82% | 59,364 psi | 89% | 3320 fps | 100% |
| Lovex S070 | <<locked>> | 82% | 57,827 psi | 87% | 3317 fps | 100% |
| Lovex S071 | <<locked>> | 94% | 57,667 psi | 86% | 3294 fps | 100% |
| Norma 204 | <<locked>> | 82% | 57,188 psi | 86% | 3346 fps | 99.9% |
| Norma 217ᴾ | <<locked>> | 100% | 53,795 psi | 81% | 3363 fps | 100% |
| Norma MRP | <<locked>> | 86% | 56,565 psi | 85% | 3392 fps | 100% |
| Norma URP | <<locked>> | 82% | 57,986 psi | 87% | 3337 fps | 100% |
| Ramshot Grand | <<locked>> | 90% | 59,988 psi | 90% | 3458 fps | 99.9% |
| Ramshot Hunter | <<locked>> | 82% | 57,159 psi | 86% | 3343 fps | 100% |
| Ramshot Magnum | <<locked>> | 92% | 58,465 psi | 88% | 3369 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,363 psi | 57% | 2251 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 82% | 59,625 psi | 89% | 3415 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 94% | 59,799 psi | 90% | 3497 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 96% | 58,929 psi | 88% | 3455 fps | 99.4% |
| Rottweil R 904 | <<locked>> | 86% | 58,001 psi | 87% | 3340 fps | 99.6% |
| Rottweil R 905 | <<locked>> | 86% | 56,608 psi | 85% | 3350 fps | 99.9% |
| Shooters World Long Rifle | <<locked>> | 82% | 59,364 psi | 89% | 3320 fps | 100% |
| Shooters World SW4350 | <<locked>> | 82% | 57,827 psi | 87% | 3317 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 82% | 58,392 psi | 88% | 3264 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 88% | 60,176 psi | 90% | 3409 fps | 100% |
| Somchem S361 | <<locked>> | 86% | 59,756 psi | 90% | 3327 fps | 99.5% |
| Somchem S365 | <<locked>> | 84% | 59,770 psi | 90% | 3337 fps | 100% |
| Somchem S385 | <<locked>> | 86% | 56,927 psi | 85% | 3314 fps | 100% |
| Vihtavuori N160 | <<locked>> | 82% | 59,567 psi | 89% | 3327 fps | 100% |
| Vihtavuori N165 | <<locked>> | 90% | 57,043 psi | 86% | 3294 fps | 100% |
| Vihtavuori N170 | <<locked>> | 94% | 56,463 psi | 85% | 3304 fps | 96.1% |
| Vihtavuori N550 | <<locked>> | 82% | 58,813 psi | 88% | 3330 fps | 100% |
| Vihtavuori N555 | <<locked>> | 88% | 59,901 psi | 90% | 3369 fps | 100% |
| Vihtavuori N560 | <<locked>> | 88% | 60,118 psi | 90% | 3465 fps | 99.6% |
| Vihtavuori N565 | <<locked>> | 92% | 56,956 psi | 85% | 3379 fps | 99.5% |
| Vihtavuori N568 | <<locked>> | 96% | 59,103 psi | 89% | 3458 fps | 99.1% |
| Vihtavuori N570 | <<locked>> | 96% | 56,275 psi | 84% | 3451 fps | 97.2% |
| Winchester 6.5 StaBALL | <<locked>> | 82% | 59,640 psi | 89% | 3264 fps | 100% |
| Winchester StaBALL HD | <<locked>> | 90% | 58,740 psi | 88% | 3432 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 88% | 57,203 psi | 86% | 3310 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% | 42,221 psi | 63% | 3015 fps | 99.6% |
| Accurate 4350 | <<locked>> | 80% | 55,898 psi | 84% | 3294 fps | 100% |
| Accurate MAGPRO | <<locked>> | 80% | 44,208 psi | 66% | 3153 fps | 96.2% |
| ADI AR 2209 | <<locked>> | 80% | 46,731 psi | 70% | 3176 fps | 98.8% |
| ADI AR 2213 | <<locked>> | 80% | 41,901 psi | 63% | 3097 fps | 96.7% |
| ADI AR 2217 | <<locked>> | 86% | 38,247 psi | 57% | 2995 fps | 95.9% |
| ADI AR 2218 | <<locked>> | 96% | 47,877 psi | 72% | 3294 fps | 95.4% |
| ADI AR 2225 | <<locked>> | 82% | 30,356 psi | 46% | 2805 fps | 95.4% |
| Alliant Reloder-16 | <<locked>> | 80% | 53,650 psi | 80% | 3304 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 80% | 46,528 psi | 70% | 3163 fps | 98.8% |
| Alliant Reloder-22 | <<locked>> | 80% | 42,569 psi | 64% | 3104 fps | 98.1% |
| Alliant Reloder-23 | <<locked>> | 80% | 41,118 psi | 62% | 3038 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 35,607 psi | 53% | 2956 fps | 99% |
| Alliant Reloder-26 | <<locked>> | 80% | 47,036 psi | 71% | 3225 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 94% | 49,197 psi | 74% | 3284 fps | 95.9% |
| Alliant Reloder-50 | <<locked>> | 98% | 48,863 psi | 73% | 3258 fps | 95.2% |
| Baschieri & Pellagri 109 | <<locked>> | 84% | 46,543 psi | 70% | 3133 fps | 95.3% |
| Bofors RP15 | <<locked>> | 80% | 39,436 psi | 59% | 3025 fps | 97% |
| Bofors RP30 | <<locked>> | 84% | 38,276 psi | 57% | 3009 fps | 96% |
| Bofors RP5 | <<locked>> | 80% | 42,569 psi | 64% | 3104 fps | 98.1% |
| Hodgdon H1000 | <<locked>> | 82% | 36,347 psi | 54% | 2949 fps | 95.8% |
| Hodgdon H4831 | <<locked>> | 80% | 44,483 psi | 67% | 3097 fps | 96.8% |
| Hodgdon H4831 SC | <<locked>> | 80% | 43,729 psi | 66% | 3081 fps | 96.6% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 50,314 psi | 75% | 3163 fps | 100% |
| Hodgdon Retumbo | 81.6 gr | 80% | 34,766 psi | 52% | 2989 fps | 96.2% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,036 psi | 42% | 1978 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 52,373 psi | 79% | 3225 fps | 99.9% |
| IMR 4831 | <<locked>> | 80% | 52,765 psi | 79% | 3228 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 45,556 psi | 68% | 3097 fps | 97.3% |
| IMR 7828 SSC | <<locked>> | 80% | 40,611 psi | 61% | 3071 fps | 96.3% |
| IMR 8133 Enduron | <<locked>> | 90% | 36,912 psi | 55% | 2986 fps | 95.3% |
| Lovex S065 | <<locked>> | 80% | 55,666 psi | 83% | 3258 fps | 100% |
| Lovex S070 | <<locked>> | 80% | 54,230 psi | 81% | 3258 fps | 100% |
| Lovex S071 | <<locked>> | 80% | 36,129 psi | 54% | 2871 fps | 98.4% |
| Norma 204 | <<locked>> | 80% | 53,476 psi | 80% | 3281 fps | 99.6% |
| Norma 217 | <<locked>> | 86% | 32,140 psi | 48% | 2871 fps | 95.5% |
| Norma MRP | <<locked>> | 80% | 45,252 psi | 68% | 3182 fps | 99.5% |
| Norma URP | <<locked>> | 80% | 54,215 psi | 81% | 3278 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 40,567 psi | 61% | 3081 fps | 96.8% |
| Ramshot Hunter | <<locked>> | 80% | 53,505 psi | 80% | 3284 fps | 100% |
| Ramshot Magnum | <<locked>> | 80% | 36,506 psi | 55% | 2936 fps | 97.2% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 28,805 psi | 43% | 2028 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 55,274 psi | 83% | 3350 fps | 100% |
| ReloadSwiss RS 76 | 87.3 gr | 80% | 34,127 psi | 51% | 2956 fps | 97.3% |
| ReloadSwiss RS 80 | <<locked>> | 88% | 42,859 psi | 64% | 3136 fps | 96.1% |
| Rottweil R 904 | <<locked>> | 80% | 47,485 psi | 71% | 3143 fps | 98.2% |
| Rottweil R 905 | <<locked>> | 80% | 46,079 psi | 69% | 3150 fps | 98.9% |
| Shooters World Long Rifle | <<locked>> | 80% | 55,666 psi | 83% | 3258 fps | 100% |
| Shooters World SW4350 | <<locked>> | 80% | 54,230 psi | 81% | 3258 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 54,694 psi | 82% | 3209 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 45,745 psi | 69% | 3143 fps | 98.8% |
| Somchem S361 | <<locked>> | 80% | 48,559 psi | 73% | 3127 fps | 97.9% |
| Somchem S365 | <<locked>> | 80% | 52,083 psi | 78% | 3222 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 46,456 psi | 70% | 3120 fps | 99.4% |
| Vihtavuori N160 | <<locked>> | 80% | 55,738 psi | 84% | 3268 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 40,509 psi | 61% | 2979 fps | 98.1% |
| Vihtavuori N170 | <<locked>> | 92% | 52,620 psi | 79% | 3235 fps | 95.1% |
| Vihtavuori N550 | <<locked>> | 80% | 55,114 psi | 83% | 3271 fps | 100% |
| Vihtavuori N555 | <<locked>> | 80% | 45,600 psi | 68% | 3127 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 44,976 psi | 67% | 3173 fps | 97.1% |
| Vihtavuori N565 | <<locked>> | 82% | 39,871 psi | 60% | 3025 fps | 95.7% |
| Vihtavuori N568 | <<locked>> | 88% | 43,830 psi | 66% | 3156 fps | 95.7% |
| Vihtavuori N570 | 97.3 gr | 92% | 48,283 psi | 72% | 3291 fps | 95% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 55,535 psi | 83% | 3205 fps | 100% |
| Winchester StaBALL HD | <<locked>> | 80% | 39,494 psi | 59% | 3091 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 42,917 psi | 64% | 3041 fps | 98.2% |
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 66 powders for 7.21 Firebird loaded with the .284 | 127gr | Geco ZERO LG. Hodgdon Retumbo delivers the highest muzzle velocity at 3,510 fps; across all powders the maximum-charge window runs from 2,205 fps to 3,510 fps. ADI AR 2218 gives the best case fill at 100 %, and 66 of the 66 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (460 MPa), the top charges use 56–90 %, leaving at least 10 % headroom. The 127.0 gr projectile in 0.284" calls for a 1:9.0 twist; slower twists will usually not stabilise this weight. ADI AR 2218, ADI AR 2225, Alliant Reloder-50 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 | 127gr | Geco ZERO LG 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.