Load Specifications
Load data in caliber 7.21 Firebird with .284 | 175gr | Barnes Solid RN bullet and 45 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-33.
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% | 58,552 psi | 88% | 2897 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 60,350 psi | 90% | 3041 fps | 99.8% |
| ADI AR 2213 | <<locked>> | 82% | 58,407 psi | 88% | 3012 fps | 100% |
| ADI AR 2217 | <<locked>> | 90% | 58,755 psi | 88% | 3005 fps | 100% |
| ADI AR 2218 | <<locked>> | 94% | 60,162 psi | 90% | 3163 fps | 100% |
| ADI AR 2225 | <<locked>> | 92% | 59,190 psi | 89% | 3028 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 82% | 58,972 psi | 88% | 3002 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 82% | 57,261 psi | 86% | 2894 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 86% | 58,711 psi | 88% | 2982 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 90% | 57,928 psi | 87% | 3061 fps | 99.8% |
| Alliant Reloder-50 | <<locked>> | 94% | 58,711 psi | 88% | 3068 fps | 99.7% |
| Baschieri & Pellagri 109 | <<locked>> | 84% | 57,885 psi | 87% | 2972 fps | 99.8% |
| Bofors RP15 | <<locked>> | 84% | 58,566 psi | 88% | 2995 fps | 100% |
| Bofors RP30 | <<locked>> | 88% | 58,653 psi | 88% | 3018 fps | 100% |
| Bofors RP5 | <<locked>> | 82% | 58,972 psi | 88% | 3002 fps | 100% |
| Hodgdon H1000 | <<locked>> | 88% | 60,002 psi | 90% | 3015 fps | 100% |
| Hodgdon H4831 | <<locked>> | 82% | 60,307 psi | 90% | 2995 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 82% | 59,306 psi | 89% | 2979 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 86% | 59,292 psi | 89% | 3087 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,276 psi | 57% | 1916 fps | 100% |
| Hodgdon US 869 | <<locked>> | 96% | 56,434 psi | 85% | 2979 fps | 96.5% |
| IMR 4955 Enduron | <<locked>> | 82% | 59,799 psi | 90% | 2963 fps | 100% |
| IMR 7828 SSC | <<locked>> | 82% | 57,116 psi | 86% | 2999 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 88% | 58,740 psi | 88% | 2936 fps | 98.2% |
| IMR 8133 Enduron | <<locked>> | 94% | 57,914 psi | 87% | 3018 fps | 100% |
| Lovex D100 | <<locked>> | 90% | 56,869 psi | 85% | 2936 fps | 97% |
| Lovex S071 | <<locked>> | 86% | 57,232 psi | 86% | 2877 fps | 100% |
| Norma 217 | <<locked>> | 94% | 59,988 psi | 90% | 3038 fps | 100% |
| Ramshot Grand | <<locked>> | 82% | 58,900 psi | 88% | 3022 fps | 100% |
| Ramshot LRT | <<locked>> | 94% | 59,205 psi | 89% | 3084 fps | 97.3% |
| Ramshot Magnum | <<locked>> | 84% | 57,377 psi | 86% | 2943 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,450 psi | 59% | 1962 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 86% | 60,075 psi | 90% | 3068 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 88% | 58,943 psi | 88% | 3051 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 90% | 56,869 psi | 85% | 2936 fps | 97% |
| SNPE Vectan SP 13 | <<locked>> | 98% | 57,421 psi | 86% | 2979 fps | 99.4% |
| Vihtavuori 20N29ᴾ | <<locked>> | 100% | 54,868 psi | 82% | 2963 fps | 98% |
| Vihtavuori 24N41 | <<locked>> | 94% | 56,913 psi | 85% | 2989 fps | 96.6% |
| Vihtavuori N165 | <<locked>> | 84% | 59,059 psi | 89% | 2920 fps | 100% |
| Vihtavuori N170 | <<locked>> | 88% | 58,784 psi | 88% | 2976 fps | 99.2% |
| Vihtavuori N565 | <<locked>> | 84% | 56,478 psi | 85% | 2969 fps | 100% |
| Vihtavuori N568 | <<locked>> | 88% | 59,045 psi | 89% | 3054 fps | 100% |
| Vihtavuori N570 | <<locked>> | 88% | 56,811 psi | 85% | 3068 fps | 99.6% |
| Winchester StaBALL HD | <<locked>> | 82% | 59,886 psi | 90% | 2995 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 82% | 58,421 psi | 88% | 2930 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% | 54,650 psi | 82% | 2841 fps | 100% |
| Accurate 8700 | <<locked>> | 88% | 38,841 psi | 58% | 2654 fps | 95.6% |
| ADI AR 2213 | <<locked>> | 80% | 54,404 psi | 82% | 2949 fps | 100% |
| ADI AR 2217 | <<locked>> | 80% | 41,263 psi | 62% | 2710 fps | 99.6% |
| ADI AR 2218 | 88.5 gr | 82% | 38,334 psi | 57% | 2730 fps | 96.1% |
| ADI AR 2225 | <<locked>> | 80% | 38,798 psi | 58% | 2687 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 55,085 psi | 83% | 2943 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 80% | 53,795 psi | 81% | 2844 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 48,037 psi | 72% | 2822 fps | 100% |
| Alliant Reloder-33 | 87.9 gr | 80% | 39,958 psi | 60% | 2720 fps | 96.5% |
| Alliant Reloder-50 | <<locked>> | 84% | 40,611 psi | 61% | 2726 fps | 96.1% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 50,792 psi | 76% | 2854 fps | 99.2% |
| Bofors RP15 | <<locked>> | 80% | 51,271 psi | 77% | 2881 fps | 100% |
| Bofors RP30 | <<locked>> | 80% | 44,831 psi | 67% | 2785 fps | 99.9% |
| Bofors RP5 | <<locked>> | 80% | 55,085 psi | 83% | 2943 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 45,063 psi | 68% | 2782 fps | 100% |
| Hodgdon H4831 | <<locked>> | 80% | 56,304 psi | 84% | 2933 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 80% | 55,405 psi | 83% | 2920 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 80% | 47,834 psi | 72% | 2910 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,834 psi | 43% | 1719 fps | 100% |
| Hodgdon US 869 | <<locked>> | 94% | 52,518 psi | 79% | 2913 fps | 95.6% |
| IMR 4955 Enduron | <<locked>> | 80% | 56,144 psi | 84% | 2910 fps | 100% |
| IMR 7828 SSC | <<locked>> | 80% | 53,374 psi | 80% | 2936 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 80% | 45,237 psi | 68% | 2700 fps | 95.1% |
| IMR 8133 Enduron | <<locked>> | 80% | 36,172 psi | 54% | 2612 fps | 98.4% |
| Lovex D100 | <<locked>> | 86% | 49,327 psi | 74% | 2805 fps | 95.2% |
| Lovex S071 | <<locked>> | 80% | 47,268 psi | 71% | 2726 fps | 100% |
| Norma 217 | <<locked>> | 80% | 36,999 psi | 55% | 2638 fps | 99.8% |
| Ramshot Grand | <<locked>> | 80% | 54,752 psi | 82% | 2959 fps | 100% |
| Ramshot LRT | <<locked>> | 90% | 51,343 psi | 77% | 2946 fps | 95.4% |
| Ramshot Magnum | <<locked>> | 80% | 49,516 psi | 74% | 2825 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,660 psi | 44% | 1759 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 47,863 psi | 72% | 2884 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 43,787 psi | 66% | 2792 fps | 99.2% |
| Shooters World 50 BMG | <<locked>> | 86% | 49,327 psi | 74% | 2805 fps | 95.2% |
| SNPE Vectan SP 13 | <<locked>> | 88% | 40,901 psi | 61% | 2677 fps | 95.9% |
| Vihtavuori 20N29 | <<locked>> | 94% | 44,208 psi | 66% | 2766 fps | 95.3% |
| Vihtavuori 24N41 | <<locked>> | 92% | 52,895 psi | 79% | 2920 fps | 95.6% |
| Vihtavuori N165 | <<locked>> | 80% | 51,764 psi | 78% | 2815 fps | 100% |
| Vihtavuori N170 | <<locked>> | 80% | 45,005 psi | 67% | 2736 fps | 96.6% |
| Vihtavuori N565 | <<locked>> | 80% | 49,284 psi | 74% | 2851 fps | 99.9% |
| Vihtavuori N568 | <<locked>> | 80% | 44,512 psi | 67% | 2802 fps | 98.9% |
| Vihtavuori N570 | 84.6 gr | 80% | 42,728 psi | 64% | 2799 fps | 96.9% |
| Winchester StaBALL HD | <<locked>> | 80% | 55,608 psi | 83% | 2940 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 54,708 psi | 82% | 2874 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 46 powders for 7.21 Firebird loaded with the .284 | 175gr | Barnes Solid RN. ADI AR 2218 delivers the highest muzzle velocity at 3,163 fps; across all powders the maximum-charge window runs from 1,916 fps to 3,163 fps. Accurate 8700 gives the best case fill at 100 %, and 46 of the 46 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 1:10.5 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-33 rank at the top here: for 7.21 Firebird with the .284 | 175gr | Barnes Solid RN 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.