Load Specifications
Load data in caliber 7.21 Firebird with .284 | 140gr | Swift A-Frame bullet and 50 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are ADI AR 2218, Vihtavuori N570 and Hodgdon Retumbo.
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% | 59,857 psi | 90% | 3199 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 52,402 psi | 79% | 3166 fps | 97.4% |
| Accurate MAGPRO | <<locked>> | 84% | 59,277 psi | 89% | 3320 fps | 99.8% |
| ADI AR 2209 | <<locked>> | 82% | 56,637 psi | 85% | 3232 fps | 100% |
| ADI AR 2213 | <<locked>> | 86% | 59,683 psi | 89% | 3317 fps | 100% |
| ADI AR 2217 | <<locked>> | 94% | 59,509 psi | 89% | 3297 fps | 100% |
| ADI AR 2218 | <<locked>> | 96% | 56,391 psi | 85% | 3363 fps | 98.9% |
| ADI AR 2225 | <<locked>> | 96% | 59,292 psi | 89% | 3317 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 84% | 60,104 psi | 90% | 3281 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 86% | 60,191 psi | 90% | 3310 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 86% | 58,421 psi | 88% | 3205 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 90% | 59,364 psi | 89% | 3284 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 82% | 59,567 psi | 89% | 3294 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 94% | 58,639 psi | 88% | 3340 fps | 98.9% |
| Alliant Reloder-50 | <<locked>> | 98% | 58,987 psi | 88% | 3330 fps | 98.6% |
| Baschieri & Pellagri 109 | <<locked>> | 88% | 59,799 psi | 90% | 3268 fps | 99.1% |
| Bofors RP15 | <<locked>> | 88% | 59,538 psi | 89% | 3297 fps | 100% |
| Bofors RP30 | <<locked>> | 92% | 59,480 psi | 89% | 3310 fps | 100% |
| Bofors RP5 | <<locked>> | 86% | 60,191 psi | 90% | 3310 fps | 100% |
| Hodgdon H1000 | <<locked>> | 90% | 56,811 psi | 85% | 3255 fps | 100% |
| Hodgdon H4831 | <<locked>> | 84% | 58,189 psi | 87% | 3241 fps | 99.8% |
| Hodgdon H4831 SC | <<locked>> | 84% | 57,087 psi | 86% | 3222 fps | 99.7% |
| Hodgdon Retumbo | <<locked>> | 90% | 59,393 psi | 89% | 3389 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,942 psi | 57% | 2129 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 84% | 57,957 psi | 87% | 3212 fps | 99.8% |
| IMR 7828 SSC | <<locked>> | 86% | 58,233 psi | 87% | 3301 fps | 100% |
| IMR 8133 Enduron | <<locked>> | 98% | 58,030 psi | 87% | 3301 fps | 100% |
| Lovex S071 | <<locked>> | 90% | 58,146 psi | 87% | 3173 fps | 100% |
| Norma 217 | <<locked>> | 98% | 59,756 psi | 90% | 3323 fps | 100% |
| Norma MRP | <<locked>> | 82% | 56,565 psi | 85% | 3261 fps | 100% |
| Ramshot Grand | <<locked>> | 86% | 60,089 psi | 90% | 3327 fps | 100% |
| Ramshot Magnum | <<locked>> | 88% | 58,639 psi | 88% | 3245 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,001 psi | 58% | 2178 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 88% | 56,159 psi | 84% | 3304 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 92% | 59,770 psi | 90% | 3343 fps | 99.9% |
| Rottweil R 904 | <<locked>> | 82% | 56,913 psi | 85% | 3202 fps | 99.9% |
| Rottweil R 905 | <<locked>> | 84% | 60,002 psi | 90% | 3274 fps | 100% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 54,157 psi | 81% | 3179 fps | 97.4% |
| SNPE Vectan Tubal 8000 | <<locked>> | 84% | 59,625 psi | 89% | 3271 fps | 100% |
| Somchem S361 | <<locked>> | 82% | 58,363 psi | 87% | 3186 fps | 99.8% |
| Somchem S385 | <<locked>> | 82% | 56,579 psi | 85% | 3179 fps | 100% |
| Vihtavuori N165 | <<locked>> | 86% | 56,681 psi | 85% | 3166 fps | 100% |
| Vihtavuori N170 | <<locked>> | 90% | 56,434 psi | 85% | 3196 fps | 97.3% |
| Vihtavuori N555 | <<locked>> | 84% | 60,017 psi | 90% | 3232 fps | 100% |
| Vihtavuori N560 | <<locked>> | 84% | 59,843 psi | 90% | 3330 fps | 99.9% |
| Vihtavuori N565 | <<locked>> | 88% | 57,479 psi | 86% | 3264 fps | 99.9% |
| Vihtavuori N568 | <<locked>> | 92% | 59,785 psi | 90% | 3340 fps | 99.7% |
| Vihtavuori N570 | <<locked>> | 92% | 57,305 psi | 86% | 3346 fps | 98.4% |
| Winchester StaBALL HD | <<locked>> | 86% | 60,104 psi | 90% | 3304 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 84% | 56,333 psi | 84% | 3176 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% | 48,907 psi | 73% | 3022 fps | 100% |
| Accurate 8700 | <<locked>> | 96% | 45,063 psi | 68% | 3025 fps | 95.4% |
| Accurate MAGPRO | <<locked>> | 80% | 51,358 psi | 77% | 3182 fps | 98.9% |
| ADI AR 2209 | <<locked>> | 80% | 52,910 psi | 79% | 3169 fps | 100% |
| ADI AR 2213 | <<locked>> | 80% | 48,298 psi | 72% | 3117 fps | 99.1% |
| ADI AR 2217 | <<locked>> | 80% | 36,143 psi | 54% | 2831 fps | 96.5% |
| ADI AR 2218 | 101 gr | 90% | 44,831 psi | 67% | 3120 fps | 95.9% |
| ADI AR 2225 | <<locked>> | 80% | 33,533 psi | 50% | 2799 fps | 98.4% |
| Alliant Reloder-19 | <<locked>> | 80% | 52,721 psi | 79% | 3159 fps | 99.9% |
| Alliant Reloder-22 | <<locked>> | 80% | 49,066 psi | 74% | 3117 fps | 99.8% |
| Alliant Reloder-23 | <<locked>> | 80% | 47,819 psi | 72% | 3035 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 41,901 psi | 63% | 2982 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 80% | 55,245 psi | 83% | 3232 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 86% | 43,192 psi | 65% | 3035 fps | 95.2% |
| Alliant Reloder-50 | <<locked>> | 92% | 47,094 psi | 71% | 3104 fps | 95.9% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 45,905 psi | 69% | 3012 fps | 96.5% |
| Bofors RP15 | <<locked>> | 80% | 45,687 psi | 68% | 3048 fps | 99.3% |
| Bofors RP30 | <<locked>> | 80% | 39,204 psi | 59% | 2917 fps | 97.5% |
| Bofors RP5 | <<locked>> | 80% | 49,066 psi | 74% | 3117 fps | 99.8% |
| Hodgdon H1000 | <<locked>> | 80% | 39,349 psi | 59% | 2917 fps | 98.1% |
| Hodgdon H4831 | <<locked>> | 80% | 50,720 psi | 76% | 3110 fps | 99.1% |
| Hodgdon H4831 SC | <<locked>> | 80% | 49,748 psi | 75% | 3091 fps | 99% |
| Hodgdon Retumbo | 84.8 gr | 80% | 41,133 psi | 62% | 3045 fps | 99.4% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,500 psi | 43% | 1909 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 50,952 psi | 76% | 3091 fps | 99.2% |
| IMR 7828 SSC | <<locked>> | 80% | 47,195 psi | 71% | 3100 fps | 99% |
| IMR 8133 Enduron | <<locked>> | 84% | 35,795 psi | 54% | 2841 fps | 96.1% |
| Lovex S071 | <<locked>> | 80% | 42,105 psi | 63% | 2890 fps | 99.9% |
| Norma 217 | <<locked>> | 80% | 31,444 psi | 47% | 2733 fps | 96.5% |
| Norma MRP | <<locked>> | 80% | 52,663 psi | 79% | 3196 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 47,892 psi | 72% | 3117 fps | 99.3% |
| Ramshot Magnum | <<locked>> | 80% | 43,395 psi | 65% | 2976 fps | 99.6% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,370 psi | 44% | 1959 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 40,886 psi | 61% | 3015 fps | 99.8% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 37,768 psi | 57% | 2894 fps | 95.4% |
| Rottweil R 904 | <<locked>> | 80% | 53,272 psi | 80% | 3140 fps | 99.7% |
| Rottweil R 905 | <<locked>> | 80% | 52,620 psi | 79% | 3153 fps | 100% |
| SNPE Vectan SP 13 | <<locked>> | 96% | 47,079 psi | 71% | 3041 fps | 95.5% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 52,272 psi | 78% | 3150 fps | 100% |
| Somchem S361 | <<locked>> | 80% | 54,607 psi | 82% | 3123 fps | 99.6% |
| Somchem S385 | <<locked>> | 80% | 52,866 psi | 79% | 3120 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 46,456 psi | 70% | 2989 fps | 99.7% |
| Vihtavuori N170 | <<locked>> | 86% | 49,211 psi | 74% | 3061 fps | 95.5% |
| Vihtavuori N555 | <<locked>> | 80% | 52,736 psi | 79% | 3123 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 52,011 psi | 78% | 3196 fps | 99.3% |
| Vihtavuori N565 | <<locked>> | 80% | 43,569 psi | 65% | 2995 fps | 98% |
| Vihtavuori N568 | <<locked>> | 80% | 38,624 psi | 58% | 2913 fps | 95.1% |
| Vihtavuori N570 | 94.6 gr | 86% | 46,021 psi | 69% | 3120 fps | 95.6% |
| Winchester StaBALL HD | <<locked>> | 80% | 47,950 psi | 72% | 3114 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 49,023 psi | 73% | 3048 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 | 140gr | Swift A-Frame. Hodgdon Retumbo delivers the highest muzzle velocity at 3,389 fps; across all powders the maximum-charge window runs from 2,129 fps to 3,389 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 1:13.0 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. ADI AR 2218, Vihtavuori N570, Hodgdon Retumbo rank at the top here: for 7.21 Firebird with the .284 | 140gr | Swift A-Frame 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.