Load Specifications
Load data in caliber 7.21 Firebird with .284 | 175gr | Speer Deep Curl Soft Point 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% | 59,350 psi | 89% | 2907 fps | 100% |
| Accurate 8700 | <<locked>> | 98% | 57,377 psi | 86% | 2999 fps | 99.6% |
| ADI AR 2213 | <<locked>> | 82% | 59,234 psi | 89% | 3022 fps | 100% |
| ADI AR 2217 | <<locked>> | 90% | 59,727 psi | 90% | 3015 fps | 100% |
| ADI AR 2218 | <<locked>> | 92% | 57,072 psi | 86% | 3110 fps | 99.9% |
| ADI AR 2225 | <<locked>> | 90% | 56,478 psi | 85% | 2989 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 82% | 59,785 psi | 90% | 3015 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 82% | 58,305 psi | 87% | 2907 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 86% | 59,930 psi | 90% | 2995 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 90% | 59,132 psi | 89% | 3077 fps | 99.9% |
| Alliant Reloder-50 | <<locked>> | 94% | 60,104 psi | 90% | 3087 fps | 99.8% |
| Baschieri & Pellagri 109 | <<locked>> | 84% | 58,827 psi | 88% | 2989 fps | 99.9% |
| Bofors RP15 | <<locked>> | 84% | 59,364 psi | 89% | 3005 fps | 100% |
| Bofors RP30 | <<locked>> | 88% | 59,814 psi | 90% | 3031 fps | 100% |
| Bofors RP5 | <<locked>> | 82% | 59,785 psi | 90% | 3015 fps | 100% |
| Hodgdon H1000 | <<locked>> | 86% | 56,956 psi | 85% | 2972 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 82% | 60,075 psi | 90% | 2992 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 84% | 56,275 psi | 84% | 3041 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,363 psi | 57% | 1926 fps | 100% |
| Hodgdon US 869 | <<locked>> | 96% | 57,595 psi | 86% | 2995 fps | 96.9% |
| IMR 7828 SSC | <<locked>> | 82% | 58,189 psi | 87% | 3012 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 88% | 59,480 psi | 89% | 2949 fps | 98.4% |
| IMR 8133 Enduron | <<locked>> | 94% | 59,234 psi | 89% | 3038 fps | 100% |
| Lovex D100 | <<locked>> | 90% | 57,928 psi | 87% | 2953 fps | 97.3% |
| Lovex S071 | <<locked>> | 86% | 58,030 psi | 87% | 2887 fps | 100% |
| Norma 217 | <<locked>> | 92% | 57,276 psi | 86% | 3002 fps | 100% |
| Ramshot Grand | <<locked>> | 82% | 60,205 psi | 90% | 3038 fps | 100% |
| Ramshot LRT | <<locked>> | 92% | 56,362 psi | 84% | 3035 fps | 96.7% |
| Ramshot Magnum | <<locked>> | 84% | 58,523 psi | 88% | 2959 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,537 psi | 59% | 1972 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 84% | 57,087 psi | 86% | 3025 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 88% | 60,234 psi | 90% | 3071 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 90% | 57,928 psi | 87% | 2953 fps | 97.3% |
| SNPE Vectan SP 13 | <<locked>> | 98% | 58,682 psi | 88% | 2999 fps | 99.5% |
| Vihtavuori 20N29ᴾ | <<locked>> | 100% | 56,072 psi | 84% | 2979 fps | 98.3% |
| Vihtavuori 24N41 | <<locked>> | 94% | 57,943 psi | 87% | 3005 fps | 96.9% |
| Vihtavuori N165 | <<locked>> | 84% | 59,973 psi | 90% | 2933 fps | 100% |
| Vihtavuori N170 | <<locked>> | 88% | 59,727 psi | 90% | 2992 fps | 99.3% |
| Vihtavuori N565 | <<locked>> | 84% | 57,406 psi | 86% | 2986 fps | 100% |
| Vihtavuori N568 | <<locked>> | 88% | 60,147 psi | 90% | 3071 fps | 100% |
| Vihtavuori N570 | <<locked>> | 88% | 57,972 psi | 87% | 3084 fps | 99.7% |
| Winchester Supreme 780 | <<locked>> | 82% | 59,350 psi | 89% | 2943 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% | 55,651 psi | 83% | 2854 fps | 100% |
| Accurate 8700 | <<locked>> | 88% | 39,726 psi | 60% | 2674 fps | 96% |
| ADI AR 2213 | <<locked>> | 80% | 55,419 psi | 83% | 2966 fps | 100% |
| ADI AR 2217 | <<locked>> | 80% | 42,177 psi | 63% | 2726 fps | 99.7% |
| ADI AR 2218 | 87.7 gr | 80% | 36,289 psi | 54% | 2674 fps | 95.1% |
| ADI AR 2225 | <<locked>> | 80% | 39,624 psi | 59% | 2700 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 56,101 psi | 84% | 2959 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 80% | 54,665 psi | 82% | 2858 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 48,878 psi | 73% | 2835 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 80% | 40,799 psi | 61% | 2736 fps | 96.8% |
| Alliant Reloder-50 | <<locked>> | 82% | 38,653 psi | 58% | 2677 fps | 95.4% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 51,561 psi | 77% | 2867 fps | 99.3% |
| Bofors RP15 | <<locked>> | 80% | 52,272 psi | 78% | 2897 fps | 100% |
| Bofors RP30 | <<locked>> | 80% | 45,788 psi | 69% | 2802 fps | 99.9% |
| Bofors RP5 | <<locked>> | 80% | 56,101 psi | 84% | 2959 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 46,035 psi | 69% | 2799 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 80% | 56,333 psi | 84% | 2936 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 80% | 48,805 psi | 73% | 2923 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,935 psi | 43% | 1726 fps | 100% |
| Hodgdon US 869 | <<locked>> | 92% | 50,024 psi | 75% | 2867 fps | 95% |
| IMR 7828 SSC | <<locked>> | 80% | 54,259 psi | 81% | 2953 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 80% | 46,021 psi | 69% | 2717 fps | 95.5% |
| IMR 8133 Enduron | <<locked>> | 80% | 36,941 psi | 55% | 2628 fps | 98.6% |
| Lovex D100 | <<locked>> | 86% | 50,328 psi | 75% | 2828 fps | 95.6% |
| Lovex S071 | <<locked>> | 80% | 48,124 psi | 72% | 2740 fps | 100% |
| Norma 217 | <<locked>> | 80% | 37,826 psi | 57% | 2654 fps | 99.9% |
| Ramshot Grand | <<locked>> | 80% | 55,840 psi | 84% | 2976 fps | 100% |
| Ramshot LRT | 98.5 gr | 90% | 52,446 psi | 79% | 2969 fps | 95.8% |
| Ramshot Magnum | <<locked>> | 80% | 50,459 psi | 76% | 2841 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,762 psi | 45% | 1765 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 48,892 psi | 73% | 2897 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 44,672 psi | 67% | 2808 fps | 99.3% |
| Shooters World 50 BMG | <<locked>> | 86% | 50,328 psi | 75% | 2828 fps | 95.6% |
| SNPE Vectan SP 13 | <<locked>> | 86% | 38,986 psi | 58% | 2635 fps | 95.3% |
| Vihtavuori 20N29 | <<locked>> | 94% | 45,353 psi | 68% | 2785 fps | 95.7% |
| Vihtavuori 24N41 | <<locked>> | 90% | 50,357 psi | 75% | 2874 fps | 95% |
| Vihtavuori N165 | <<locked>> | 80% | 52,692 psi | 79% | 2828 fps | 100% |
| Vihtavuori N170 | <<locked>> | 80% | 45,643 psi | 68% | 2746 fps | 96.9% |
| Vihtavuori N565 | <<locked>> | 80% | 50,241 psi | 75% | 2867 fps | 100% |
| Vihtavuori N568 | <<locked>> | 80% | 45,397 psi | 68% | 2818 fps | 99.1% |
| Vihtavuori N570 | 85.9 gr | 80% | 43,526 psi | 65% | 2815 fps | 97.2% |
| Winchester Supreme 780 | <<locked>> | 80% | 55,463 psi | 83% | 2884 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 | Speer Deep Curl Soft Point. ADI AR 2218 delivers the highest muzzle velocity at 3,110 fps; across all powders the maximum-charge window runs from 1,926 fps to 3,110 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 | Speer Deep Curl Soft Point they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Hodgdon 50BMG 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.