Load Specifications
Load data in caliber 7.21 Firebird with .284 | 160gr | Speer Hot-Cor bullet and 49 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 Alliant Reloder-50.
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% | 60,104 psi | 90% | 3031 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 57,464 psi | 86% | 3104 fps | 99.2% |
| Accurate MAGPRO | <<locked>> | 82% | 59,596 psi | 89% | 3159 fps | 100% |
| ADI AR 2213 | <<locked>> | 84% | 60,060 psi | 90% | 3150 fps | 100% |
| ADI AR 2217 | <<locked>> | 92% | 60,263 psi | 90% | 3140 fps | 100% |
| ADI AR 2218 | <<locked>> | 94% | 57,159 psi | 86% | 3222 fps | 99.7% |
| ADI AR 2225 | <<locked>> | 92% | 56,362 psi | 84% | 3104 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 82% | 60,292 psi | 90% | 3110 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 82% | 56,695 psi | 85% | 3084 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 84% | 58,769 psi | 88% | 3031 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 88% | 60,263 psi | 90% | 3120 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 92% | 59,437 psi | 89% | 3196 fps | 99.6% |
| Alliant Reloder-50 | <<locked>> | 96% | 60,176 psi | 90% | 3196 fps | 99.5% |
| Baschieri & Pellagri 109 | <<locked>> | 86% | 59,814 psi | 90% | 3110 fps | 99.7% |
| Bofors RP15 | <<locked>> | 86% | 59,959 psi | 90% | 3130 fps | 100% |
| Bofors RP30 | <<locked>> | 90% | 60,234 psi | 90% | 3153 fps | 100% |
| Bofors RP5 | <<locked>> | 82% | 56,695 psi | 85% | 3084 fps | 100% |
| Hodgdon H1000 | <<locked>> | 88% | 57,479 psi | 86% | 3094 fps | 100% |
| Hodgdon H4831 | <<locked>> | 82% | 58,073 psi | 87% | 3074 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 82% | 57,145 psi | 86% | 3058 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 86% | 56,420 psi | 85% | 3166 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,174 psi | 57% | 2005 fps | 100% |
| Hodgdon US 869 | <<locked>> | 98% | 58,044 psi | 87% | 3104 fps | 96% |
| IMR 4955 Enduron | <<locked>> | 82% | 57,899 psi | 87% | 3048 fps | 100% |
| IMR 7828 SSC | <<locked>> | 84% | 58,740 psi | 88% | 3136 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 88% | 56,768 psi | 85% | 3009 fps | 97.1% |
| IMR 8133 Enduron | <<locked>> | 96% | 59,234 psi | 89% | 3153 fps | 100% |
| Lovex D100 | <<locked>> | 92% | 58,784 psi | 88% | 3068 fps | 96.6% |
| Lovex S071 | <<locked>> | 88% | 58,581 psi | 88% | 3012 fps | 100% |
| Norma 217 | <<locked>> | 94% | 57,116 psi | 86% | 3114 fps | 100% |
| Ramshot Grand | <<locked>> | 82% | 56,391 psi | 85% | 3100 fps | 100% |
| Ramshot Magnum | <<locked>> | 86% | 59,016 psi | 88% | 3081 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,291 psi | 59% | 2051 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 86% | 57,261 psi | 86% | 3146 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 88% | 56,231 psi | 84% | 3123 fps | 100% |
| Rottweil R 905 | <<locked>> | 82% | 60,249 psi | 90% | 3107 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 92% | 58,784 psi | 88% | 3068 fps | 96.6% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 58,972 psi | 88% | 3110 fps | 99.1% |
| SNPE Vectan Tubal 8000 | <<locked>> | 82% | 59,886 psi | 90% | 3104 fps | 100% |
| Vihtavuori 20N29ᴾ | <<locked>> | 100% | 52,228 psi | 78% | 3012 fps | 96.7% |
| Vihtavuori 24N41 | <<locked>> | 96% | 58,595 psi | 88% | 3117 fps | 96.1% |
| Vihtavuori N165 | <<locked>> | 84% | 56,884 psi | 85% | 3002 fps | 100% |
| Vihtavuori N170 | <<locked>> | 88% | 56,550 psi | 85% | 3045 fps | 98.4% |
| Vihtavuori N560 | <<locked>> | 82% | 60,205 psi | 90% | 3169 fps | 100% |
| Vihtavuori N565 | <<locked>> | 86% | 57,914 psi | 87% | 3107 fps | 100% |
| Vihtavuori N568 | <<locked>> | 88% | 56,376 psi | 85% | 3123 fps | 99.9% |
| Vihtavuori N570 | <<locked>> | 90% | 58,218 psi | 87% | 3199 fps | 99.3% |
| Winchester StaBALL HD | <<locked>> | 82% | 56,884 psi | 85% | 3077 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 84% | 60,365 psi | 90% | 3068 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% | 52,678 psi | 79% | 2923 fps | 100% |
| Accurate 8700 | <<locked>> | 92% | 42,786 psi | 64% | 2835 fps | 96.1% |
| Accurate MAGPRO | <<locked>> | 80% | 55,579 psi | 83% | 3097 fps | 99.9% |
| ADI AR 2213 | <<locked>> | 80% | 52,286 psi | 78% | 3025 fps | 100% |
| ADI AR 2217 | <<locked>> | 80% | 39,421 psi | 59% | 2769 fps | 98.8% |
| ADI AR 2218 | 92.7 gr | 84% | 39,291 psi | 59% | 2844 fps | 95.3% |
| ADI AR 2225 | <<locked>> | 80% | 36,753 psi | 55% | 2740 fps | 99.9% |
| Alliant Reloder-19 | <<locked>> | 80% | 56,463 psi | 85% | 3054 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 52,997 psi | 79% | 3022 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 80% | 51,663 psi | 77% | 2930 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 45,788 psi | 69% | 2894 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 82% | 40,973 psi | 61% | 2841 fps | 95.9% |
| Alliant Reloder-50 | 96.4 gr | 86% | 41,539 psi | 62% | 2838 fps | 95.4% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 49,095 psi | 74% | 2927 fps | 98.4% |
| Bofors RP15 | <<locked>> | 80% | 49,342 psi | 74% | 2959 fps | 100% |
| Bofors RP30 | <<locked>> | 80% | 42,859 psi | 64% | 2848 fps | 99.3% |
| Bofors RP5 | <<locked>> | 80% | 52,997 psi | 79% | 3022 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 43,018 psi | 64% | 2844 fps | 99.7% |
| Hodgdon H4831 | <<locked>> | 80% | 54,288 psi | 81% | 3015 fps | 99.9% |
| Hodgdon H4831 SC | <<locked>> | 80% | 53,403 psi | 80% | 2999 fps | 99.9% |
| Hodgdon Retumbo | <<locked>> | 80% | 45,252 psi | 68% | 2972 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,689 psi | 43% | 1795 fps | 100% |
| Hodgdon US 869 | <<locked>> | 96% | 54,085 psi | 81% | 3038 fps | 95% |
| IMR 4955 Enduron | <<locked>> | 80% | 54,259 psi | 81% | 2989 fps | 99.9% |
| IMR 7828 SSC | <<locked>> | 80% | 51,213 psi | 77% | 3012 fps | 99.9% |
| IMR 7977 Enduron | <<locked>> | 84% | 49,879 psi | 75% | 2887 fps | 95.5% |
| IMR 8133 Enduron | <<locked>> | 80% | 34,316 psi | 51% | 2661 fps | 96.9% |
| Lovex D100 | <<locked>> | 90% | 54,592 psi | 82% | 2999 fps | 95.7% |
| Lovex S071 | <<locked>> | 80% | 45,513 psi | 68% | 2802 fps | 100% |
| Norma 217 | <<locked>> | 80% | 34,998 psi | 52% | 2687 fps | 99% |
| Ramshot Grand | <<locked>> | 80% | 52,431 psi | 79% | 3035 fps | 100% |
| Ramshot Magnum | <<locked>> | 80% | 47,384 psi | 71% | 2897 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,602 psi | 44% | 1841 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 45,368 psi | 68% | 2949 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 41,568 psi | 62% | 2844 fps | 98.1% |
| Rottweil R 905 | <<locked>> | 80% | 56,507 psi | 85% | 3051 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 90% | 54,592 psi | 82% | 2999 fps | 95.7% |
| SNPE Vectan SP 13 | <<locked>> | 90% | 41,756 psi | 63% | 2792 fps | 95.3% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 56,159 psi | 84% | 3045 fps | 100% |
| Vihtavuori 20N29 | <<locked>> | 98% | 48,704 psi | 73% | 2946 fps | 95.7% |
| Vihtavuori 24N41 | <<locked>> | 94% | 54,520 psi | 82% | 3048 fps | 95.1% |
| Vihtavuori N165 | <<locked>> | 80% | 49,908 psi | 75% | 2894 fps | 100% |
| Vihtavuori N170 | <<locked>> | 80% | 43,163 psi | 65% | 2792 fps | 95.1% |
| Vihtavuori N560 | <<locked>> | 80% | 56,115 psi | 84% | 3104 fps | 100% |
| Vihtavuori N565 | <<locked>> | 80% | 47,239 psi | 71% | 2920 fps | 99.5% |
| Vihtavuori N568 | <<locked>> | 80% | 42,322 psi | 63% | 2858 fps | 97.8% |
| Vihtavuori N570 | 86.5 gr | 80% | 40,553 psi | 61% | 2848 fps | 95.2% |
| Winchester StaBALL HD | <<locked>> | 80% | 52,852 psi | 79% | 3018 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 52,736 psi | 79% | 2953 fps | 100% |
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 49 powders for 7.21 Firebird loaded with the .284 | 160gr | Speer Hot-Cor. ADI AR 2218 delivers the highest muzzle velocity at 3,222 fps; across all powders the maximum-charge window runs from 2,005 fps to 3,222 fps. Accurate 8700 gives the best case fill at 100 %, and 49 of the 49 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 160.0 gr projectile in 0.284" calls for a 1:12.0 twist; slower twists will usually not stabilise this weight. Accurate 8700, Hodgdon TrailBoss, 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, Alliant Reloder-50 rank at the top here: for 7.21 Firebird with the .284 | 160gr | Speer Hot-Cor 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.