Load Specifications
Load data in caliber 7.21 Firebird with .284 | 175gr | A-Square MONO RN bullet and 33 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are ADI AR 2218, Ramshot LRT 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 8700 | <<locked>> | 96% | 56,376 psi | 85% | 2979 fps | 99.6% |
| ADI AR 2217 | <<locked>> | 88% | 58,436 psi | 88% | 2995 fps | 100% |
| ADI AR 2218 | <<locked>> | 90% | 56,057 psi | 84% | 3087 fps | 99.9% |
| ADI AR 2225 | <<locked>> | 90% | 59,335 psi | 89% | 3018 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 84% | 58,581 psi | 88% | 2972 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 88% | 57,914 psi | 87% | 3054 fps | 99.9% |
| Alliant Reloder-50 | <<locked>> | 92% | 58,885 psi | 88% | 3061 fps | 99.8% |
| Baschieri & Pellagri 109 | <<locked>> | 82% | 57,159 psi | 86% | 2963 fps | 99.9% |
| Bofors RP15 | <<locked>> | 82% | 57,856 psi | 87% | 2982 fps | 100% |
| Bofors RP30 | <<locked>> | 86% | 58,523 psi | 88% | 3009 fps | 100% |
| Hodgdon H1000 | <<locked>> | 86% | 59,654 psi | 89% | 3009 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 84% | 59,190 psi | 89% | 3081 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,464 psi | 58% | 1939 fps | 100% |
| Hodgdon US 869 | <<locked>> | 94% | 56,333 psi | 84% | 2976 fps | 96.8% |
| IMR 7977 Enduron | <<locked>> | 86% | 57,812 psi | 87% | 2930 fps | 98.3% |
| IMR 8133 Enduron | <<locked>> | 92% | 58,175 psi | 87% | 3018 fps | 100% |
| Lovex D100 | <<locked>> | 88% | 56,347 psi | 84% | 2933 fps | 97.3% |
| Lovex S071 | <<locked>> | 86% | 60,321 psi | 90% | 2920 fps | 100% |
| Norma 217 | <<locked>> | 92% | 60,147 psi | 90% | 3035 fps | 100% |
| Ramshot LRT | <<locked>> | 92% | 59,146 psi | 89% | 3077 fps | 97.5% |
| Ramshot Magnum | <<locked>> | 82% | 56,927 psi | 85% | 2936 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,610 psi | 59% | 1985 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 84% | 60,133 psi | 90% | 3058 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 86% | 58,856 psi | 88% | 3045 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 88% | 56,347 psi | 84% | 2933 fps | 97.3% |
| SNPE Vectan SP 13 | <<locked>> | 96% | 57,522 psi | 86% | 2979 fps | 99.5% |
| Vihtavuori 20N29ᴾ | <<locked>> | 100% | 59,205 psi | 89% | 3025 fps | 98.9% |
| Vihtavuori 24N41 | <<locked>> | 92% | 56,739 psi | 85% | 2986 fps | 96.8% |
| Vihtavuori N165 | <<locked>> | 82% | 58,291 psi | 87% | 2910 fps | 100% |
| Vihtavuori N170 | <<locked>> | 86% | 58,233 psi | 87% | 2972 fps | 99.3% |
| Vihtavuori N565 | <<locked>> | 84% | 59,944 psi | 90% | 3018 fps | 100% |
| Vihtavuori N568 | <<locked>> | 86% | 58,871 psi | 88% | 3048 fps | 100% |
| Vihtavuori N570 | <<locked>> | 86% | 56,840 psi | 85% | 3061 fps | 99.7% |
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 8700 | <<locked>> | 86% | 39,088 psi | 59% | 2654 fps | 95.9% |
| ADI AR 2217 | <<locked>> | 80% | 44,121 psi | 66% | 2762 fps | 99.9% |
| ADI AR 2218 | 91.2 gr | 80% | 38,218 psi | 57% | 2723 fps | 96.2% |
| ADI AR 2225 | <<locked>> | 80% | 41,727 psi | 63% | 2736 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 51,140 psi | 77% | 2867 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 80% | 43,047 psi | 65% | 2782 fps | 97.6% |
| Alliant Reloder-50 | 92.6 gr | 80% | 37,927 psi | 57% | 2651 fps | 95.2% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 53,505 psi | 80% | 2904 fps | 99.6% |
| Bofors RP15 | <<locked>> | 80% | 54,230 psi | 81% | 2927 fps | 100% |
| Bofors RP30 | <<locked>> | 80% | 47,892 psi | 72% | 2838 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 48,182 psi | 72% | 2831 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 80% | 51,329 psi | 77% | 2959 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,993 psi | 43% | 1736 fps | 100% |
| Hodgdon US 869 | <<locked>> | 92% | 52,518 psi | 79% | 2910 fps | 95.9% |
| IMR 7977 Enduron | <<locked>> | 80% | 47,558 psi | 71% | 2749 fps | 96.1% |
| IMR 8133 Enduron | <<locked>> | 80% | 38,798 psi | 58% | 2664 fps | 99.1% |
| Lovex D100 | <<locked>> | 84% | 48,936 psi | 73% | 2802 fps | 95.5% |
| Lovex S071 | <<locked>> | 80% | 49,937 psi | 75% | 2769 fps | 100% |
| Norma 217 | <<locked>> | 80% | 39,958 psi | 60% | 2694 fps | 100% |
| Ramshot LRT | 100.2 gr | 88% | 51,372 psi | 77% | 2943 fps | 95.7% |
| Ramshot Magnum | <<locked>> | 80% | 52,852 psi | 79% | 2874 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,805 psi | 45% | 1778 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 51,706 psi | 78% | 2936 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 47,094 psi | 71% | 2848 fps | 99.7% |
| Shooters World 50 BMG | <<locked>> | 84% | 48,936 psi | 73% | 2802 fps | 95.5% |
| SNPE Vectan SP 13 | <<locked>> | 84% | 38,218 psi | 57% | 2612 fps | 95.1% |
| Vihtavuori 20N29 | <<locked>> | 92% | 44,657 psi | 67% | 2769 fps | 95.7% |
| Vihtavuori 24N41 | <<locked>> | 90% | 52,794 psi | 79% | 2917 fps | 95.9% |
| Vihtavuori N165 | <<locked>> | 80% | 54,679 psi | 82% | 2861 fps | 100% |
| Vihtavuori N170 | <<locked>> | 80% | 47,601 psi | 71% | 2785 fps | 97.5% |
| Vihtavuori N565 | <<locked>> | 80% | 52,446 psi | 79% | 2904 fps | 100% |
| Vihtavuori N568 | <<locked>> | 80% | 47,703 psi | 72% | 2858 fps | 99.5% |
| Vihtavuori N570 | <<locked>> | 80% | 45,876 psi | 69% | 2861 fps | 98% |
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 34 powders for 7.21 Firebird loaded with the .284 | 175gr | A-Square MONO RN. ADI AR 2218 delivers the highest muzzle velocity at 3,087 fps; across all powders the maximum-charge window runs from 1,939 fps to 3,087 fps. Hodgdon TrailBoss gives the best case fill at 100 %, and 34 of the 34 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (460 MPa), the top charges use 58–90 %, leaving at least 10 % headroom. The 175.0 gr projectile in 0.284" calls for a 1:16.5 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, Ramshot LRT, Alliant Reloder-50 rank at the top here: for 7.21 Firebird with the .284 | 175gr | A-Square MONO RN 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.