Load Specifications
Load data in caliber 7.21 Firebird with .284 | 139gr | Hornady SP bullet and 52 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% | 59,248 psi | 89% | 3199 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 51,488 psi | 77% | 3156 fps | 97.1% |
| Accurate MAGPRO | <<locked>> | 84% | 58,494 psi | 88% | 3320 fps | 99.7% |
| ADI AR 2209 | <<locked>> | 84% | 59,973 psi | 90% | 3294 fps | 100% |
| ADI AR 2213 | <<locked>> | 86% | 59,088 psi | 89% | 3317 fps | 100% |
| ADI AR 2217 | <<locked>> | 94% | 58,653 psi | 88% | 3294 fps | 100% |
| ADI AR 2218 | <<locked>> | 98% | 60,002 psi | 90% | 3438 fps | 99.4% |
| ADI AR 2225 | <<locked>> | 96% | 58,421 psi | 88% | 3314 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 84% | 59,509 psi | 89% | 3281 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 86% | 59,567 psi | 89% | 3310 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 86% | 57,580 psi | 86% | 3202 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 90% | 58,726 psi | 88% | 3287 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 82% | 58,711 psi | 88% | 3294 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 94% | 57,638 psi | 86% | 3330 fps | 98.7% |
| Alliant Reloder-50 | <<locked>> | 98% | 57,957 psi | 87% | 3320 fps | 98.4% |
| Baschieri & Pellagri 109 | <<locked>> | 88% | 59,132 psi | 89% | 3268 fps | 99% |
| Bofors RP15 | <<locked>> | 88% | 58,914 psi | 88% | 3297 fps | 100% |
| Bofors RP30 | <<locked>> | 92% | 58,639 psi | 88% | 3307 fps | 100% |
| Bofors RP5 | <<locked>> | 86% | 59,567 psi | 89% | 3310 fps | 100% |
| Hodgdon H1000 | <<locked>> | 92% | 60,133 psi | 90% | 3314 fps | 100% |
| Hodgdon H4831 | <<locked>> | 84% | 57,464 psi | 86% | 3238 fps | 99.7% |
| Hodgdon H4831 SC | <<locked>> | 84% | 56,550 psi | 85% | 3225 fps | 99.7% |
| Hodgdon Hybrid 100V | <<locked>> | 82% | 60,046 psi | 90% | 3186 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 90% | 58,421 psi | 88% | 3386 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,927 psi | 57% | 2133 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 84% | 57,435 psi | 86% | 3212 fps | 99.8% |
| IMR 7828 SSC | <<locked>> | 86% | 57,609 psi | 86% | 3297 fps | 99.9% |
| IMR 7977 Enduron | <<locked>> | 92% | 60,017 psi | 90% | 3219 fps | 96.4% |
| IMR 8133 Enduron | <<locked>> | 98% | 57,217 psi | 86% | 3297 fps | 100% |
| Lovex S071 | <<locked>> | 90% | 57,580 psi | 86% | 3173 fps | 100% |
| Norma 217 | <<locked>> | 98% | 58,871 psi | 88% | 3320 fps | 100% |
| Norma MRP | <<locked>> | 84% | 59,857 psi | 90% | 3323 fps | 100% |
| Ramshot Grand | <<locked>> | 86% | 59,219 psi | 89% | 3323 fps | 100% |
| Ramshot Magnum | <<locked>> | 88% | 57,856 psi | 87% | 3241 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,972 psi | 58% | 2182 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 90% | 59,857 psi | 90% | 3369 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 92% | 58,958 psi | 88% | 3337 fps | 99.8% |
| Rottweil R 904 | <<locked>> | 84% | 60,176 psi | 90% | 3264 fps | 100% |
| Rottweil R 905 | <<locked>> | 84% | 59,408 psi | 89% | 3274 fps | 100% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 53,272 psi | 80% | 3169 fps | 97.1% |
| SNPE Vectan Tubal 8000 | <<locked>> | 84% | 59,030 psi | 88% | 3271 fps | 100% |
| Somchem S361 | <<locked>> | 82% | 57,856 psi | 87% | 3186 fps | 99.8% |
| Somchem S385 | <<locked>> | 84% | 59,785 psi | 90% | 3238 fps | 100% |
| Vihtavuori N165 | <<locked>> | 88% | 59,959 psi | 90% | 3225 fps | 100% |
| Vihtavuori N170 | <<locked>> | 92% | 59,712 psi | 90% | 3258 fps | 97.8% |
| Vihtavuori N555 | <<locked>> | 84% | 59,393 psi | 89% | 3235 fps | 100% |
| Vihtavuori N560 | <<locked>> | 84% | 59,059 psi | 89% | 3330 fps | 99.9% |
| Vihtavuori N565 | <<locked>> | 88% | 56,724 psi | 85% | 3261 fps | 99.8% |
| Vihtavuori N568 | <<locked>> | 92% | 58,972 psi | 88% | 3337 fps | 99.6% |
| Vihtavuori N570 | <<locked>> | 92% | 56,463 psi | 85% | 3340 fps | 98.2% |
| Winchester StaBALL HD | <<locked>> | 86% | 59,146 psi | 89% | 3301 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 86% | 59,857 psi | 90% | 3238 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% | 48,356 psi | 72% | 3022 fps | 100% |
| Accurate 8700 | <<locked>> | 98% | 47,703 psi | 72% | 3084 fps | 96.1% |
| Accurate MAGPRO | <<locked>> | 80% | 50,749 psi | 76% | 3179 fps | 98.7% |
| ADI AR 2209 | <<locked>> | 80% | 52,504 psi | 79% | 3173 fps | 99.9% |
| ADI AR 2213 | <<locked>> | 80% | 47,732 psi | 72% | 3110 fps | 99% |
| ADI AR 2217 | <<locked>> | 80% | 35,665 psi | 53% | 2825 fps | 96.1% |
| ADI AR 2218 | 100.4 gr | 90% | 44,193 psi | 66% | 3110 fps | 95.4% |
| ADI AR 2225 | <<locked>> | 80% | 33,069 psi | 50% | 2795 fps | 98.1% |
| Alliant Reloder-19 | <<locked>> | 80% | 52,214 psi | 78% | 3159 fps | 99.9% |
| Alliant Reloder-22 | <<locked>> | 80% | 48,501 psi | 73% | 3114 fps | 99.7% |
| Alliant Reloder-23 | <<locked>> | 80% | 47,253 psi | 71% | 3038 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 41,481 psi | 62% | 2982 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 80% | 54,592 psi | 82% | 3232 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 88% | 45,934 psi | 69% | 3104 fps | 96% |
| Alliant Reloder-50 | <<locked>> | 92% | 46,180 psi | 69% | 3094 fps | 95.5% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 45,469 psi | 68% | 3009 fps | 96.2% |
| Bofors RP15 | <<locked>> | 80% | 45,165 psi | 68% | 3045 fps | 99.2% |
| Bofors RP30 | <<locked>> | 80% | 38,696 psi | 58% | 2910 fps | 97.2% |
| Bofors RP5 | <<locked>> | 80% | 48,501 psi | 73% | 3114 fps | 99.7% |
| Hodgdon H1000 | <<locked>> | 80% | 38,841 psi | 58% | 2910 fps | 97.9% |
| Hodgdon H4831 | <<locked>> | 80% | 50,183 psi | 75% | 3107 fps | 99% |
| Hodgdon H4831 SC | <<locked>> | 80% | 49,211 psi | 74% | 3091 fps | 98.8% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 56,304 psi | 84% | 3133 fps | 100% |
| Hodgdon Retumbo | 84.3 gr | 80% | 40,538 psi | 61% | 3041 fps | 99.2% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,427 psi | 43% | 1913 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 50,618 psi | 76% | 3094 fps | 99.1% |
| IMR 7828 SSC | <<locked>> | 80% | 46,601 psi | 70% | 3097 fps | 98.8% |
| IMR 7977 Enduron | <<locked>> | 90% | 56,333 psi | 84% | 3159 fps | 95.6% |
| IMR 8133 Enduron | <<locked>> | 84% | 35,288 psi | 53% | 2838 fps | 95.8% |
| Lovex S071 | <<locked>> | 80% | 41,713 psi | 63% | 2890 fps | 99.9% |
| Norma 217 | <<locked>> | 80% | 30,937 psi | 46% | 2726 fps | 96.1% |
| Norma MRP | <<locked>> | 80% | 52,069 psi | 78% | 3192 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 47,268 psi | 71% | 3114 fps | 99.2% |
| Ramshot Magnum | <<locked>> | 80% | 42,815 psi | 64% | 2976 fps | 99.5% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,298 psi | 44% | 1962 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 40,306 psi | 60% | 3012 fps | 99.7% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 37,086 psi | 56% | 2887 fps | 95% |
| Rottweil R 904 | <<locked>> | 80% | 52,750 psi | 79% | 3140 fps | 99.6% |
| Rottweil R 905 | <<locked>> | 80% | 52,040 psi | 78% | 3150 fps | 99.9% |
| SNPE Vectan SP 13 | <<locked>> | 96% | 46,441 psi | 70% | 3038 fps | 95.2% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 51,706 psi | 78% | 3150 fps | 99.9% |
| Somchem S361 | <<locked>> | 80% | 54,143 psi | 81% | 3123 fps | 99.5% |
| Somchem S385 | <<locked>> | 80% | 52,315 psi | 78% | 3120 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 45,934 psi | 69% | 2986 fps | 99.7% |
| Vihtavuori N170 | <<locked>> | 86% | 48,559 psi | 73% | 3054 fps | 95.2% |
| Vihtavuori N555 | <<locked>> | 80% | 52,112 psi | 78% | 3123 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 51,445 psi | 77% | 3192 fps | 99.2% |
| Vihtavuori N565 | <<locked>> | 80% | 43,033 psi | 65% | 2992 fps | 97.8% |
| Vihtavuori N568 | <<locked>> | 82% | 41,002 psi | 61% | 2982 fps | 95.9% |
| Vihtavuori N570 | 94 gr | 86% | 45,295 psi | 68% | 3114 fps | 95.3% |
| Winchester StaBALL HD | <<locked>> | 80% | 47,036 psi | 71% | 3110 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 48,472 psi | 73% | 3045 fps | 99.7% |
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 59 powders for 7.21 Firebird loaded with the .284 | 139gr | Hornady SP. ADI AR 2218 delivers the highest muzzle velocity at 3,438 fps; across all powders the maximum-charge window runs from 2,133 fps to 3,438 fps. Accurate 8700 gives the best case fill at 100 %, and 59 of the 59 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 139.0 gr projectile in 0.284" calls for a 1:12.0 twist; slower twists will usually not stabilise this weight. Accurate 8700, Hodgdon TrailBoss, Hodgdon US 869 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 | 139gr | Hornady SP they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Hodgdon 50BMG, Hodgdon US 869, Lovex D100 burn incompletely and react more sensitively to barrel length and temperature. Always begin at the start load and work up in small increments while checking case and primer for pressure signs.