Load Specifications
Load data in caliber 7.21 Firebird with .284 | 140gr | Barnes X S 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 Vihtavuori N570.
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>> | 84% | 58,842 psi | 88% | 3173 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 54,578 psi | 82% | 3202 fps | 97.8% |
| Accurate MAGPRO | <<locked>> | 82% | 57,435 psi | 86% | 3284 fps | 99.6% |
| ADI AR 2209 | <<locked>> | 82% | 58,378 psi | 88% | 3255 fps | 100% |
| ADI AR 2213 | <<locked>> | 84% | 57,522 psi | 86% | 3274 fps | 99.9% |
| ADI AR 2217 | <<locked>> | 92% | 57,319 psi | 86% | 3261 fps | 100% |
| ADI AR 2218 | <<locked>> | 96% | 58,363 psi | 87% | 3396 fps | 99.1% |
| ADI AR 2225 | <<locked>> | 94% | 57,435 psi | 86% | 3287 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 82% | 58,189 psi | 87% | 3245 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 84% | 58,421 psi | 88% | 3271 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 84% | 56,956 psi | 85% | 3176 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 88% | 57,725 psi | 87% | 3255 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 92% | 56,652 psi | 85% | 3304 fps | 98.6% |
| Alliant Reloder-50 | <<locked>> | 96% | 57,957 psi | 87% | 3310 fps | 98.4% |
| Baschieri & Pellagri 109 | <<locked>> | 86% | 57,261 psi | 86% | 3219 fps | 98.8% |
| Bofors RP15 | <<locked>> | 86% | 57,827 psi | 87% | 3264 fps | 100% |
| Bofors RP30 | <<locked>> | 90% | 57,856 psi | 87% | 3281 fps | 100% |
| Bofors RP5 | <<locked>> | 84% | 58,421 psi | 88% | 3271 fps | 100% |
| Hodgdon H1000 | <<locked>> | 90% | 58,595 psi | 88% | 3278 fps | 100% |
| Hodgdon H4831 | <<locked>> | 84% | 59,828 psi | 90% | 3258 fps | 99.9% |
| Hodgdon H4831 SC | <<locked>> | 84% | 58,885 psi | 88% | 3245 fps | 99.8% |
| Hodgdon Retumbo | <<locked>> | 88% | 57,290 psi | 86% | 3353 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,189 psi | 57% | 2123 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 84% | 59,611 psi | 89% | 3232 fps | 99.9% |
| IMR 7828 SSC | <<locked>> | 86% | 60,162 psi | 90% | 3323 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 90% | 58,378 psi | 88% | 3176 fps | 96% |
| IMR 8133 Enduron | <<locked>> | 96% | 56,869 psi | 85% | 3278 fps | 100% |
| Lovex S071 | <<locked>> | 88% | 57,406 psi | 86% | 3153 fps | 100% |
| Norma 217 | <<locked>> | 96% | 58,479 psi | 88% | 3301 fps | 100% |
| Norma MRP | <<locked>> | 82% | 58,842 psi | 88% | 3291 fps | 100% |
| Ramshot Grand | <<locked>> | 84% | 57,972 psi | 87% | 3287 fps | 100% |
| Ramshot Magnum | <<locked>> | 86% | 56,681 psi | 85% | 3209 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,320 psi | 59% | 2172 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 88% | 58,523 psi | 88% | 3340 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 90% | 57,986 psi | 87% | 3307 fps | 99.8% |
| Rottweil R 904 | <<locked>> | 82% | 58,610 psi | 88% | 3219 fps | 100% |
| Rottweil R 905 | <<locked>> | 82% | 58,233 psi | 87% | 3238 fps | 100% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 56,608 psi | 85% | 3215 fps | 97.8% |
| SNPE Vectan Tubal 8000 | <<locked>> | 82% | 57,856 psi | 87% | 3235 fps | 100% |
| Somchem S361 | <<locked>> | 82% | 60,249 psi | 90% | 3205 fps | 99.9% |
| Somchem S385 | <<locked>> | 82% | 58,755 psi | 88% | 3205 fps | 100% |
| Vihtavuori N165 | <<locked>> | 86% | 58,755 psi | 88% | 3189 fps | 100% |
| Vihtavuori N170 | <<locked>> | 90% | 58,711 psi | 88% | 3225 fps | 97.6% |
| Vihtavuori N555 | <<locked>> | 82% | 58,856 psi | 88% | 3209 fps | 100% |
| Vihtavuori N560 | <<locked>> | 82% | 57,885 psi | 87% | 3294 fps | 99.8% |
| Vihtavuori N565 | <<locked>> | 88% | 59,901 psi | 90% | 3294 fps | 100% |
| Vihtavuori N568 | <<locked>> | 90% | 58,059 psi | 87% | 3310 fps | 99.6% |
| Vihtavuori N570 | <<locked>> | 92% | 59,553 psi | 89% | 3379 fps | 98.7% |
| Winchester StaBALL HD | <<locked>> | 84% | 58,421 psi | 88% | 3278 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 84% | 58,334 psi | 87% | 3199 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% | 51,866 psi | 78% | 3064 fps | 100% |
| Accurate 8700 | <<locked>> | 94% | 44,280 psi | 66% | 3002 fps | 95% |
| Accurate MAGPRO | <<locked>> | 80% | 53,722 psi | 81% | 3219 fps | 99.2% |
| ADI AR 2209 | <<locked>> | 80% | 54,824 psi | 82% | 3192 fps | 100% |
| ADI AR 2213 | <<locked>> | 80% | 50,227 psi | 75% | 3146 fps | 99.4% |
| ADI AR 2217 | <<locked>> | 80% | 38,334 psi | 57% | 2881 fps | 97.3% |
| ADI AR 2218 | 96.6 gr | 88% | 43,932 psi | 66% | 3091 fps | 95.4% |
| ADI AR 2225 | <<locked>> | 80% | 35,984 psi | 54% | 2864 fps | 99.2% |
| Alliant Reloder-19 | <<locked>> | 80% | 54,578 psi | 82% | 3186 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 51,314 psi | 77% | 3153 fps | 99.9% |
| Alliant Reloder-23 | <<locked>> | 80% | 50,111 psi | 75% | 3068 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 44,353 psi | 66% | 3025 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 84% | 42,714 psi | 64% | 3022 fps | 95% |
| Alliant Reloder-50 | <<locked>> | 90% | 46,934 psi | 70% | 3100 fps | 95.8% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 47,369 psi | 71% | 3035 fps | 96.8% |
| Bofors RP15 | <<locked>> | 80% | 47,921 psi | 72% | 3087 fps | 99.6% |
| Bofors RP30 | <<locked>> | 80% | 41,843 psi | 63% | 2972 fps | 98.2% |
| Bofors RP5 | <<locked>> | 80% | 51,314 psi | 77% | 3153 fps | 99.9% |
| Hodgdon H1000 | <<locked>> | 80% | 41,524 psi | 62% | 2959 fps | 98.7% |
| Hodgdon H4831 | <<locked>> | 80% | 52,620 psi | 79% | 3136 fps | 99.3% |
| Hodgdon H4831 SC | <<locked>> | 80% | 51,648 psi | 77% | 3117 fps | 99.2% |
| Hodgdon Retumbo | 82.9 gr | 80% | 43,468 psi | 65% | 3094 fps | 99.7% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,848 psi | 43% | 1906 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 52,721 psi | 79% | 3114 fps | 99.4% |
| IMR 7828 SSC | <<locked>> | 80% | 49,255 psi | 74% | 3133 fps | 99.3% |
| IMR 7977 Enduron | <<locked>> | 88% | 54,897 psi | 82% | 3117 fps | 95.2% |
| IMR 8133 Enduron | <<locked>> | 80% | 33,823 psi | 51% | 2782 fps | 95.3% |
| Lovex S071 | <<locked>> | 80% | 45,107 psi | 68% | 2940 fps | 100% |
| Norma 217 | <<locked>> | 80% | 34,505 psi | 52% | 2818 fps | 97.9% |
| Norma MRP | <<locked>> | 80% | 54,940 psi | 82% | 3228 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 50,198 psi | 75% | 3153 fps | 99.6% |
| Ramshot Magnum | <<locked>> | 80% | 45,847 psi | 69% | 3018 fps | 99.8% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,646 psi | 44% | 1952 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 43,439 psi | 65% | 3074 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 40,538 psi | 61% | 2963 fps | 96.5% |
| Rottweil R 904 | <<locked>> | 80% | 55,158 psi | 83% | 3159 fps | 99.8% |
| Rottweil R 905 | <<locked>> | 80% | 54,723 psi | 82% | 3182 fps | 100% |
| SNPE Vectan SP 13 | <<locked>> | 94% | 46,383 psi | 70% | 3022 fps | 95.3% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 54,360 psi | 81% | 3176 fps | 100% |
| Somchem S361 | <<locked>> | 80% | 56,507 psi | 85% | 3146 fps | 99.7% |
| Somchem S385 | <<locked>> | 80% | 55,158 psi | 83% | 3146 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 48,602 psi | 73% | 3018 fps | 99.9% |
| Vihtavuori N170 | <<locked>> | 84% | 48,341 psi | 72% | 3031 fps | 95.2% |
| Vihtavuori N555 | <<locked>> | 80% | 55,347 psi | 83% | 3156 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 54,070 psi | 81% | 3228 fps | 99.5% |
| Vihtavuori N565 | <<locked>> | 80% | 46,369 psi | 70% | 3051 fps | 98.6% |
| Vihtavuori N568 | <<locked>> | 80% | 41,336 psi | 62% | 2976 fps | 96.2% |
| Vihtavuori N570 | 90.3 gr | 84% | 45,237 psi | 68% | 3100 fps | 95.3% |
| Winchester StaBALL HD | <<locked>> | 80% | 50,633 psi | 76% | 3159 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 51,140 psi | 77% | 3077 fps | 99.9% |
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 | 140gr | Barnes X S. ADI AR 2218 delivers the highest muzzle velocity at 3,396 fps; across all powders the maximum-charge window runs from 2,123 fps to 3,396 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 140.0 gr projectile in 0.284" calls for a 1:10.5 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, Vihtavuori N570 rank at the top here: for 7.21 Firebird with the .284 | 140gr | Barnes X S 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.