Load Specifications
Load data in caliber 7.21 Firebird with .284 | 175gr | Woodleigh PP SN bullet and 42 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 Ramshot LRT.
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>> | 82% | 59,059 psi | 89% | 2900 fps | 100% |
| Accurate 8700 | <<locked>> | 98% | 57,029 psi | 85% | 2992 fps | 99.6% |
| ADI AR 2213 | <<locked>> | 82% | 58,943 psi | 88% | 3018 fps | 100% |
| ADI AR 2217 | <<locked>> | 90% | 59,495 psi | 89% | 3012 fps | 100% |
| ADI AR 2218 | <<locked>> | 92% | 56,695 psi | 85% | 3107 fps | 99.9% |
| ADI AR 2225 | <<locked>> | 92% | 60,133 psi | 90% | 3038 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 82% | 59,538 psi | 89% | 3009 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 82% | 58,030 psi | 87% | 2904 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 86% | 59,480 psi | 89% | 2992 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 90% | 58,769 psi | 88% | 3071 fps | 99.9% |
| Alliant Reloder-50 | <<locked>> | 94% | 59,669 psi | 89% | 3081 fps | 99.8% |
| Baschieri & Pellagri 109 | <<locked>> | 84% | 58,479 psi | 88% | 2982 fps | 99.9% |
| Bofors RP15 | <<locked>> | 84% | 59,103 psi | 89% | 3002 fps | 100% |
| Bofors RP30 | <<locked>> | 88% | 59,553 psi | 89% | 3028 fps | 100% |
| Bofors RP5 | <<locked>> | 82% | 59,538 psi | 89% | 3009 fps | 100% |
| Hodgdon H1000 | <<locked>> | 86% | 56,739 psi | 85% | 2972 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 82% | 59,843 psi | 90% | 2989 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 86% | 60,147 psi | 90% | 3100 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,305 psi | 57% | 1923 fps | 100% |
| Hodgdon US 869 | <<locked>> | 96% | 57,276 psi | 86% | 2995 fps | 96.8% |
| IMR 7828 SSC | <<locked>> | 82% | 57,899 psi | 87% | 3009 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 88% | 59,306 psi | 89% | 2946 fps | 98.3% |
| IMR 8133 Enduron | <<locked>> | 94% | 58,813 psi | 88% | 3031 fps | 100% |
| Lovex D100 | <<locked>> | 90% | 57,566 psi | 86% | 2949 fps | 97.3% |
| Lovex S071 | <<locked>> | 86% | 57,769 psi | 87% | 2884 fps | 100% |
| Norma 217 | <<locked>> | 92% | 56,797 psi | 85% | 2995 fps | 100% |
| Ramshot Grand | <<locked>> | 82% | 59,727 psi | 90% | 3031 fps | 100% |
| Ramshot LRT | <<locked>> | 94% | 60,162 psi | 90% | 3097 fps | 97.5% |
| Ramshot Magnum | <<locked>> | 84% | 58,088 psi | 87% | 2953 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,479 psi | 59% | 1969 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 84% | 56,623 psi | 85% | 3018 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 88% | 59,843 psi | 90% | 3064 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 90% | 57,566 psi | 86% | 2949 fps | 97.3% |
| SNPE Vectan SP 13 | <<locked>> | 98% | 58,320 psi | 87% | 2995 fps | 99.5% |
| Vihtavuori 20N29ᴾ | <<locked>> | 100% | 55,724 psi | 84% | 2976 fps | 98.2% |
| Vihtavuori 24N41 | <<locked>> | 94% | 57,595 psi | 86% | 2999 fps | 96.8% |
| Vihtavuori N165 | <<locked>> | 84% | 59,756 psi | 90% | 2930 fps | 100% |
| Vihtavuori N170 | <<locked>> | 88% | 59,538 psi | 89% | 2989 fps | 99.3% |
| Vihtavuori N565 | <<locked>> | 84% | 57,188 psi | 86% | 2982 fps | 100% |
| Vihtavuori N568 | <<locked>> | 88% | 59,915 psi | 90% | 3068 fps | 100% |
| Vihtavuori N570 | <<locked>> | 88% | 57,740 psi | 87% | 3081 fps | 99.7% |
| Winchester Supreme 780 | <<locked>> | 82% | 59,117 psi | 89% | 2936 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% | 55,390 psi | 83% | 2851 fps | 100% |
| Accurate 8700 | <<locked>> | 88% | 39,523 psi | 59% | 2671 fps | 95.9% |
| ADI AR 2213 | <<locked>> | 80% | 55,158 psi | 83% | 2959 fps | 100% |
| ADI AR 2217 | <<locked>> | 80% | 41,930 psi | 63% | 2723 fps | 99.7% |
| ADI AR 2218 | 87.3 gr | 80% | 36,100 psi | 54% | 2667 fps | 95% |
| ADI AR 2225 | <<locked>> | 80% | 39,334 psi | 59% | 2697 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 55,840 psi | 84% | 2953 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 80% | 54,418 psi | 82% | 2854 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 48,602 psi | 73% | 2828 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 80% | 40,567 psi | 61% | 2733 fps | 96.7% |
| Alliant Reloder-50 | <<locked>> | 82% | 38,435 psi | 58% | 2671 fps | 95.3% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 51,372 psi | 77% | 2864 fps | 99.3% |
| Bofors RP15 | <<locked>> | 80% | 51,996 psi | 78% | 2894 fps | 100% |
| Bofors RP30 | <<locked>> | 80% | 45,542 psi | 68% | 2799 fps | 99.9% |
| Bofors RP5 | <<locked>> | 80% | 55,840 psi | 84% | 2953 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 45,774 psi | 69% | 2792 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 80% | 56,086 psi | 84% | 2930 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 80% | 48,501 psi | 73% | 2920 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,834 psi | 43% | 1722 fps | 100% |
| Hodgdon US 869 | <<locked>> | 94% | 53,359 psi | 80% | 2927 fps | 95.8% |
| IMR 7828 SSC | <<locked>> | 80% | 53,983 psi | 81% | 2946 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 80% | 45,847 psi | 69% | 2713 fps | 95.4% |
| IMR 8133 Enduron | <<locked>> | 80% | 36,695 psi | 55% | 2621 fps | 98.5% |
| Lovex D100 | <<locked>> | 86% | 49,966 psi | 75% | 2818 fps | 95.5% |
| Lovex S071 | <<locked>> | 80% | 47,834 psi | 72% | 2736 fps | 100% |
| Norma 217 | <<locked>> | 80% | 37,565 psi | 56% | 2651 fps | 99.8% |
| Ramshot Grand | <<locked>> | 80% | 55,564 psi | 83% | 2972 fps | 100% |
| Ramshot LRT | 98 gr | 90% | 52,069 psi | 78% | 2959 fps | 95.6% |
| Ramshot Magnum | <<locked>> | 80% | 50,212 psi | 75% | 2835 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,805 psi | 45% | 1765 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 48,631 psi | 73% | 2894 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 44,440 psi | 67% | 2802 fps | 99.3% |
| Shooters World 50 BMG | <<locked>> | 86% | 49,966 psi | 75% | 2818 fps | 95.5% |
| SNPE Vectan SP 13 | <<locked>> | 86% | 38,667 psi | 58% | 2628 fps | 95.1% |
| Vihtavuori 20N29 | <<locked>> | 94% | 45,020 psi | 67% | 2782 fps | 95.6% |
| Vihtavuori 24N41 | <<locked>> | 92% | 53,780 psi | 81% | 2936 fps | 95.9% |
| Vihtavuori N165 | <<locked>> | 80% | 52,460 psi | 79% | 2825 fps | 100% |
| Vihtavuori N170 | <<locked>> | 80% | 45,426 psi | 68% | 2743 fps | 96.8% |
| Vihtavuori N565 | <<locked>> | 80% | 49,995 psi | 75% | 2864 fps | 100% |
| Vihtavuori N568 | <<locked>> | 80% | 45,165 psi | 68% | 2815 fps | 99.1% |
| Vihtavuori N570 | 85.5 gr | 80% | 43,265 psi | 65% | 2812 fps | 97.1% |
| Winchester Supreme 780 | <<locked>> | 80% | 55,230 psi | 83% | 2881 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 43 powders for 7.21 Firebird loaded with the .284 | 175gr | Woodleigh PP SN. ADI AR 2218 delivers the highest muzzle velocity at 3,107 fps; across all powders the maximum-charge window runs from 1,923 fps to 3,107 fps. Hodgdon TrailBoss gives the best case fill at 100 %, and 43 of the 43 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 175.0 gr projectile in 0.284" calls for a 1:11.5 twist; slower twists will usually not stabilise this weight. Hodgdon TrailBoss, ReloadSwiss RS 14, Vihtavuori 20N29 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, Ramshot LRT rank at the top here: for 7.21 Firebird with the .284 | 175gr | Woodleigh PP SN 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.