Load Specifications
Load data in caliber 7.21 Firebird with .284 | 174gr | Prvi Partizan FMJ BT 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% | 59,437 psi | 89% | 2913 fps | 100% |
| Accurate 8700 | <<locked>> | 98% | 57,363 psi | 86% | 3005 fps | 99.6% |
| ADI AR 2213 | <<locked>> | 82% | 59,306 psi | 89% | 3031 fps | 100% |
| ADI AR 2217 | <<locked>> | 90% | 59,799 psi | 90% | 3025 fps | 100% |
| ADI AR 2218 | <<locked>> | 92% | 57,101 psi | 86% | 3117 fps | 99.9% |
| ADI AR 2225 | <<locked>> | 90% | 56,333 psi | 84% | 2992 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 82% | 59,901 psi | 90% | 3022 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 82% | 58,247 psi | 87% | 2913 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 86% | 59,843 psi | 90% | 3002 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 90% | 59,161 psi | 89% | 3087 fps | 99.9% |
| Alliant Reloder-50 | <<locked>> | 94% | 60,075 psi | 90% | 3091 fps | 99.8% |
| Baschieri & Pellagri 109 | <<locked>> | 84% | 58,885 psi | 88% | 2995 fps | 99.9% |
| Bofors RP15 | <<locked>> | 84% | 59,480 psi | 89% | 3015 fps | 100% |
| Bofors RP30 | <<locked>> | 88% | 59,901 psi | 90% | 3041 fps | 100% |
| Bofors RP5 | <<locked>> | 82% | 59,901 psi | 90% | 3022 fps | 100% |
| Hodgdon H1000 | <<locked>> | 86% | 57,058 psi | 86% | 2982 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 82% | 60,162 psi | 90% | 3002 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 84% | 56,376 psi | 85% | 3051 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,305 psi | 57% | 1929 fps | 100% |
| Hodgdon US 869 | <<locked>> | 96% | 57,551 psi | 86% | 3005 fps | 96.8% |
| IMR 7828 SSC | <<locked>> | 82% | 58,102 psi | 87% | 3018 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 88% | 59,567 psi | 89% | 2959 fps | 98.3% |
| IMR 8133 Enduron | <<locked>> | 94% | 59,277 psi | 89% | 3045 fps | 100% |
| Lovex D100 | <<locked>> | 90% | 57,914 psi | 87% | 2959 fps | 97.3% |
| Lovex S071 | <<locked>> | 86% | 58,146 psi | 87% | 2897 fps | 100% |
| Norma 217 | <<locked>> | 92% | 57,334 psi | 86% | 3009 fps | 100% |
| Ramshot Grand | <<locked>> | 82% | 60,104 psi | 90% | 3045 fps | 100% |
| Ramshot LRT | <<locked>> | 92% | 56,333 psi | 84% | 3041 fps | 96.7% |
| Ramshot Magnum | <<locked>> | 84% | 58,610 psi | 88% | 2966 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,465 psi | 59% | 1975 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 84% | 56,942 psi | 85% | 3028 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 88% | 60,249 psi | 90% | 3077 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 90% | 57,914 psi | 87% | 2959 fps | 97.3% |
| SNPE Vectan SP 13 | <<locked>> | 98% | 58,668 psi | 88% | 3005 fps | 99.5% |
| Vihtavuori 20N29ᴾ | <<locked>> | 100% | 56,188 psi | 84% | 2989 fps | 98.3% |
| Vihtavuori 24N41 | <<locked>> | 94% | 58,117 psi | 87% | 3015 fps | 96.9% |
| Vihtavuori N165 | <<locked>> | 84% | 59,886 psi | 90% | 2940 fps | 100% |
| Vihtavuori N170 | <<locked>> | 88% | 59,741 psi | 90% | 2999 fps | 99.3% |
| Vihtavuori N565 | <<locked>> | 84% | 57,508 psi | 86% | 2995 fps | 100% |
| Vihtavuori N568 | <<locked>> | 88% | 60,191 psi | 90% | 3077 fps | 100% |
| Vihtavuori N570 | <<locked>> | 88% | 58,030 psi | 87% | 3091 fps | 99.7% |
| Winchester Supreme 780 | <<locked>> | 82% | 59,451 psi | 89% | 2949 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% | 55,579 psi | 83% | 2861 fps | 100% |
| Accurate 8700 | <<locked>> | 88% | 39,769 psi | 60% | 2680 fps | 96% |
| ADI AR 2213 | <<locked>> | 80% | 55,361 psi | 83% | 2969 fps | 100% |
| ADI AR 2217 | <<locked>> | 80% | 42,148 psi | 63% | 2730 fps | 99.7% |
| ADI AR 2218 | 88.1 gr | 80% | 36,347 psi | 54% | 2680 fps | 95.1% |
| ADI AR 2225 | <<locked>> | 80% | 39,711 psi | 60% | 2710 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 56,028 psi | 84% | 2963 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 80% | 54,621 psi | 82% | 2864 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 48,994 psi | 73% | 2841 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 80% | 40,843 psi | 61% | 2746 fps | 96.8% |
| Alliant Reloder-50 | <<locked>> | 82% | 38,696 psi | 58% | 2684 fps | 95.4% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 51,634 psi | 77% | 2877 fps | 99.3% |
| Bofors RP15 | <<locked>> | 80% | 52,214 psi | 78% | 2904 fps | 100% |
| Bofors RP30 | <<locked>> | 80% | 45,716 psi | 69% | 2808 fps | 99.9% |
| Bofors RP5 | <<locked>> | 80% | 56,028 psi | 84% | 2963 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 45,992 psi | 69% | 2802 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 80% | 56,246 psi | 84% | 2940 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 80% | 48,921 psi | 73% | 2930 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,906 psi | 43% | 1729 fps | 100% |
| Hodgdon US 869 | <<locked>> | 94% | 53,664 psi | 80% | 2940 fps | 95.9% |
| IMR 7828 SSC | <<locked>> | 80% | 54,375 psi | 82% | 2959 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 80% | 45,977 psi | 69% | 2723 fps | 95.4% |
| IMR 8133 Enduron | <<locked>> | 80% | 36,883 psi | 55% | 2635 fps | 98.6% |
| Lovex D100 | <<locked>> | 86% | 50,343 psi | 75% | 2835 fps | 95.6% |
| Lovex S071 | <<locked>> | 80% | 48,066 psi | 72% | 2746 fps | 100% |
| Norma 217 | <<locked>> | 80% | 37,797 psi | 57% | 2657 fps | 99.8% |
| Ramshot Grand | <<locked>> | 80% | 55,941 psi | 84% | 2982 fps | 100% |
| Ramshot LRT | 98.9 gr | 90% | 52,460 psi | 79% | 2972 fps | 95.7% |
| Ramshot Magnum | <<locked>> | 80% | 50,560 psi | 76% | 2848 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,733 psi | 45% | 1772 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 48,979 psi | 73% | 2907 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 44,730 psi | 67% | 2815 fps | 99.3% |
| Shooters World 50 BMG | <<locked>> | 86% | 50,343 psi | 75% | 2835 fps | 95.6% |
| SNPE Vectan SP 13 | <<locked>> | 86% | 38,928 psi | 58% | 2638 fps | 95.2% |
| Vihtavuori 20N29 | <<locked>> | 94% | 45,382 psi | 68% | 2792 fps | 95.7% |
| Vihtavuori 24N41 | <<locked>> | 92% | 54,114 psi | 81% | 2949 fps | 96% |
| Vihtavuori N165 | <<locked>> | 80% | 52,649 psi | 79% | 2835 fps | 100% |
| Vihtavuori N170 | <<locked>> | 80% | 45,687 psi | 68% | 2753 fps | 96.8% |
| Vihtavuori N565 | <<locked>> | 80% | 50,183 psi | 75% | 2874 fps | 100% |
| Vihtavuori N568 | <<locked>> | 80% | 45,324 psi | 68% | 2822 fps | 99.1% |
| Vihtavuori N570 | 86.3 gr | 80% | 43,584 psi | 65% | 2822 fps | 97.2% |
| Winchester Supreme 780 | <<locked>> | 80% | 55,579 psi | 83% | 2894 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 42 powders for 7.21 Firebird loaded with the .284 | 174gr | Prvi Partizan FMJ BT. ADI AR 2218 delivers the highest muzzle velocity at 3,117 fps; across all powders the maximum-charge window runs from 1,929 fps to 3,117 fps. Hodgdon TrailBoss gives the best case fill at 100 %, and 42 of the 42 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 174.0 gr projectile in 0.284" calls for a 1:12.0 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 | 174gr | Prvi Partizan FMJ BT 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.