Load Specifications
Load data in caliber 7.21 Firebird with .284 | 140gr | Sierra Pro-Hunter 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% | 59,915 psi | 90% | 3199 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 52,330 psi | 78% | 3166 fps | 97.4% |
| Accurate MAGPRO | <<locked>> | 84% | 59,132 psi | 89% | 3320 fps | 99.7% |
| ADI AR 2209 | <<locked>> | 82% | 56,710 psi | 85% | 3235 fps | 100% |
| ADI AR 2213 | <<locked>> | 86% | 59,596 psi | 89% | 3314 fps | 100% |
| ADI AR 2217 | <<locked>> | 94% | 59,364 psi | 89% | 3294 fps | 100% |
| ADI AR 2218 | <<locked>> | 96% | 56,260 psi | 84% | 3363 fps | 98.9% |
| ADI AR 2225 | <<locked>> | 96% | 59,176 psi | 89% | 3317 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 84% | 60,191 psi | 90% | 3281 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 86% | 60,060 psi | 90% | 3304 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 86% | 58,305 psi | 87% | 3199 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 90% | 59,466 psi | 89% | 3284 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 82% | 59,466 psi | 89% | 3294 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 94% | 58,508 psi | 88% | 3337 fps | 98.9% |
| Alliant Reloder-50 | <<locked>> | 98% | 58,856 psi | 88% | 3330 fps | 98.6% |
| Baschieri & Pellagri 109 | <<locked>> | 88% | 59,698 psi | 89% | 3268 fps | 99.1% |
| Bofors RP15 | <<locked>> | 88% | 59,611 psi | 89% | 3297 fps | 100% |
| Bofors RP30 | <<locked>> | 92% | 59,335 psi | 89% | 3310 fps | 100% |
| Bofors RP5 | <<locked>> | 86% | 60,060 psi | 90% | 3304 fps | 100% |
| Hodgdon H1000 | <<locked>> | 90% | 56,681 psi | 85% | 3251 fps | 100% |
| Hodgdon H4831 | <<locked>> | 84% | 58,088 psi | 87% | 3241 fps | 99.8% |
| Hodgdon H4831 SC | <<locked>> | 84% | 57,000 psi | 85% | 3222 fps | 99.7% |
| Hodgdon Retumbo | <<locked>> | 90% | 59,248 psi | 89% | 3389 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,971 psi | 57% | 2129 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 84% | 58,044 psi | 87% | 3215 fps | 99.8% |
| IMR 7828 SSC | <<locked>> | 86% | 58,291 psi | 87% | 3301 fps | 100% |
| IMR 8133 Enduron | <<locked>> | 98% | 58,117 psi | 87% | 3301 fps | 100% |
| Lovex S071 | <<locked>> | 90% | 58,044 psi | 87% | 3173 fps | 100% |
| Norma 217 | <<locked>> | 98% | 59,640 psi | 89% | 3323 fps | 100% |
| Norma MRP | <<locked>> | 82% | 56,420 psi | 85% | 3258 fps | 100% |
| Ramshot Grand | <<locked>> | 86% | 59,988 psi | 90% | 3323 fps | 100% |
| Ramshot Magnum | <<locked>> | 88% | 58,552 psi | 88% | 3241 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,030 psi | 59% | 2178 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 88% | 56,014 psi | 84% | 3301 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 92% | 59,683 psi | 89% | 3340 fps | 99.9% |
| Rottweil R 904 | <<locked>> | 82% | 56,797 psi | 85% | 3199 fps | 99.9% |
| Rottweil R 905 | <<locked>> | 84% | 60,075 psi | 90% | 3274 fps | 100% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 54,041 psi | 81% | 3176 fps | 97.4% |
| SNPE Vectan Tubal 8000 | <<locked>> | 84% | 59,698 psi | 89% | 3271 fps | 100% |
| Somchem S361 | <<locked>> | 82% | 58,421 psi | 88% | 3186 fps | 99.8% |
| Somchem S385 | <<locked>> | 84% | 60,263 psi | 90% | 3235 fps | 100% |
| Vihtavuori N165 | <<locked>> | 86% | 56,739 psi | 85% | 3166 fps | 100% |
| Vihtavuori N170 | <<locked>> | 92% | 60,307 psi | 90% | 3261 fps | 98% |
| Vihtavuori N555 | <<locked>> | 84% | 59,886 psi | 90% | 3232 fps | 100% |
| Vihtavuori N560 | <<locked>> | 84% | 59,727 psi | 90% | 3330 fps | 99.9% |
| Vihtavuori N565 | <<locked>> | 88% | 57,348 psi | 86% | 3261 fps | 99.9% |
| Vihtavuori N568 | <<locked>> | 92% | 59,669 psi | 89% | 3340 fps | 99.7% |
| Vihtavuori N570 | <<locked>> | 92% | 57,217 psi | 86% | 3343 fps | 98.4% |
| Winchester StaBALL HD | <<locked>> | 86% | 59,988 psi | 90% | 3301 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 86% | 60,321 psi | 90% | 3235 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% | 48,820 psi | 73% | 3022 fps | 100% |
| Accurate 8700 | <<locked>> | 96% | 44,947 psi | 67% | 3022 fps | 95.3% |
| Accurate MAGPRO | <<locked>> | 80% | 51,416 psi | 77% | 3182 fps | 98.9% |
| ADI AR 2209 | <<locked>> | 80% | 52,997 psi | 79% | 3173 fps | 100% |
| ADI AR 2213 | <<locked>> | 80% | 48,356 psi | 72% | 3117 fps | 99.2% |
| ADI AR 2217 | <<locked>> | 80% | 36,042 psi | 54% | 2828 fps | 96.4% |
| ADI AR 2218 | 101 gr | 90% | 44,889 psi | 67% | 3120 fps | 95.9% |
| ADI AR 2225 | <<locked>> | 80% | 33,446 psi | 50% | 2799 fps | 98.4% |
| Alliant Reloder-19 | <<locked>> | 80% | 52,634 psi | 79% | 3159 fps | 99.9% |
| Alliant Reloder-22 | <<locked>> | 80% | 49,124 psi | 74% | 3117 fps | 99.8% |
| Alliant Reloder-23 | <<locked>> | 80% | 47,747 psi | 72% | 3035 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 41,974 psi | 63% | 2982 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 80% | 55,303 psi | 83% | 3232 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 86% | 43,120 psi | 65% | 3035 fps | 95.1% |
| Alliant Reloder-50 | <<locked>> | 92% | 46,963 psi | 70% | 3100 fps | 95.8% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 45,818 psi | 69% | 3012 fps | 96.4% |
| Bofors RP15 | <<locked>> | 80% | 45,600 psi | 68% | 3045 fps | 99.3% |
| Bofors RP30 | <<locked>> | 80% | 39,131 psi | 59% | 2913 fps | 97.5% |
| Bofors RP5 | <<locked>> | 80% | 49,124 psi | 74% | 3117 fps | 99.8% |
| Hodgdon H1000 | <<locked>> | 80% | 39,378 psi | 59% | 2917 fps | 98.2% |
| Hodgdon H4831 | <<locked>> | 80% | 50,633 psi | 76% | 3110 fps | 99.1% |
| Hodgdon H4831 SC | <<locked>> | 80% | 49,806 psi | 75% | 3094 fps | 99% |
| Hodgdon Retumbo | 84.7 gr | 80% | 41,046 psi | 62% | 3041 fps | 99.4% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,529 psi | 43% | 1913 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 51,010 psi | 76% | 3091 fps | 99.2% |
| IMR 7828 SSC | <<locked>> | 80% | 47,094 psi | 71% | 3097 fps | 99% |
| IMR 8133 Enduron | <<locked>> | 84% | 35,723 psi | 54% | 2838 fps | 96.1% |
| Lovex S071 | <<locked>> | 80% | 42,148 psi | 63% | 2894 fps | 99.9% |
| Norma 217 | <<locked>> | 80% | 31,473 psi | 47% | 2733 fps | 96.5% |
| Norma MRP | <<locked>> | 80% | 52,547 psi | 79% | 3192 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 47,950 psi | 72% | 3117 fps | 99.3% |
| Ramshot Magnum | <<locked>> | 80% | 43,279 psi | 65% | 2972 fps | 99.6% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,254 psi | 44% | 1955 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 40,930 psi | 61% | 3018 fps | 99.8% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 37,681 psi | 56% | 2894 fps | 95.3% |
| Rottweil R 904 | <<locked>> | 80% | 53,330 psi | 80% | 3140 fps | 99.7% |
| Rottweil R 905 | <<locked>> | 80% | 52,504 psi | 79% | 3153 fps | 100% |
| SNPE Vectan SP 13 | <<locked>> | 96% | 46,992 psi | 70% | 3041 fps | 95.5% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 52,156 psi | 78% | 3146 fps | 99.9% |
| Somchem S361 | <<locked>> | 80% | 54,534 psi | 82% | 3123 fps | 99.5% |
| Somchem S385 | <<locked>> | 80% | 52,910 psi | 79% | 3120 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 46,340 psi | 69% | 2986 fps | 99.7% |
| Vihtavuori N170 | <<locked>> | 86% | 49,124 psi | 74% | 3058 fps | 95.5% |
| Vihtavuori N555 | <<locked>> | 80% | 52,620 psi | 79% | 3120 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 51,909 psi | 78% | 3196 fps | 99.3% |
| Vihtavuori N565 | <<locked>> | 80% | 43,468 psi | 65% | 2992 fps | 98% |
| Vihtavuori N568 | <<locked>> | 80% | 38,653 psi | 58% | 2913 fps | 95.1% |
| Vihtavuori N570 | 94.5 gr | 86% | 45,948 psi | 69% | 3120 fps | 95.6% |
| Winchester StaBALL HD | <<locked>> | 80% | 47,834 psi | 72% | 3114 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 49,066 psi | 74% | 3051 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 57 powders for 7.21 Firebird loaded with the .284 | 140gr | Sierra Pro-Hunter. 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 57 of the 57 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 1:12.5 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 | 140gr | Sierra Pro-Hunter they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Hodgdon US 869, Vihtavuori 20N29, Vihtavuori 24N41 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.