Load Specifications
Load data in caliber 7.21 Firebird with .284 | 165gr | Remington SP Core-Lokt bullet and 44 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% | 57,928 psi | 87% | 2963 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 59,756 psi | 90% | 3104 fps | 99.6% |
| ADI AR 2213 | <<locked>> | 82% | 57,711 psi | 87% | 3077 fps | 100% |
| ADI AR 2217 | <<locked>> | 90% | 58,073 psi | 87% | 3068 fps | 100% |
| ADI AR 2218 | <<locked>> | 94% | 59,509 psi | 89% | 3222 fps | 99.9% |
| ADI AR 2225 | <<locked>> | 92% | 58,479 psi | 88% | 3091 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 82% | 58,305 psi | 87% | 3068 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 82% | 56,710 psi | 85% | 2963 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 86% | 58,218 psi | 87% | 3051 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 90% | 57,319 psi | 86% | 3120 fps | 99.6% |
| Alliant Reloder-50 | <<locked>> | 94% | 58,044 psi | 87% | 3123 fps | 99.4% |
| Baschieri & Pellagri 109 | <<locked>> | 84% | 57,406 psi | 86% | 3035 fps | 99.7% |
| Bofors RP15 | <<locked>> | 84% | 57,885 psi | 87% | 3061 fps | 100% |
| Bofors RP30 | <<locked>> | 88% | 58,030 psi | 87% | 3084 fps | 100% |
| Bofors RP5 | <<locked>> | 82% | 58,305 psi | 87% | 3068 fps | 100% |
| Hodgdon H1000 | <<locked>> | 88% | 59,292 psi | 89% | 3084 fps | 100% |
| Hodgdon H4831 | <<locked>> | 82% | 59,814 psi | 90% | 3061 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 82% | 58,653 psi | 88% | 3045 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 86% | 58,436 psi | 88% | 3153 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,334 psi | 57% | 1982 fps | 100% |
| Hodgdon US 869 | <<locked>> | 98% | 59,901 psi | 90% | 3100 fps | 96.8% |
| IMR 4955 Enduron | <<locked>> | 82% | 59,277 psi | 89% | 3031 fps | 100% |
| IMR 7828 SSC | <<locked>> | 82% | 56,463 psi | 85% | 3061 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 88% | 58,131 psi | 87% | 2995 fps | 97.7% |
| IMR 8133 Enduron | <<locked>> | 94% | 57,435 psi | 86% | 3084 fps | 100% |
| Lovex D100 | <<locked>> | 90% | 56,434 psi | 85% | 2995 fps | 96.5% |
| Lovex S071 | <<locked>> | 88% | 60,162 psi | 90% | 2992 fps | 100% |
| Norma 217 | <<locked>> | 94% | 59,219 psi | 89% | 3104 fps | 100% |
| Ramshot Grand | <<locked>> | 82% | 58,218 psi | 87% | 3084 fps | 100% |
| Ramshot LRT | <<locked>> | 94% | 58,697 psi | 88% | 3143 fps | 96.7% |
| Ramshot Magnum | <<locked>> | 84% | 56,710 psi | 85% | 3009 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,320 psi | 59% | 2024 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 86% | 59,495 psi | 89% | 3136 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 88% | 58,276 psi | 87% | 3114 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 90% | 56,434 psi | 85% | 2995 fps | 96.5% |
| SNPE Vectan SP 13 | <<locked>> | 98% | 56,927 psi | 85% | 3041 fps | 99.1% |
| Vihtavuori 20N29ᴾ | <<locked>> | 100% | 54,331 psi | 81% | 3015 fps | 97.5% |
| Vihtavuori N165 | <<locked>> | 84% | 58,552 psi | 88% | 2989 fps | 100% |
| Vihtavuori N170 | <<locked>> | 88% | 58,204 psi | 87% | 3038 fps | 98.8% |
| Vihtavuori N565 | <<locked>> | 86% | 59,785 psi | 90% | 3094 fps | 100% |
| Vihtavuori N568 | <<locked>> | 88% | 58,363 psi | 87% | 3117 fps | 100% |
| Vihtavuori N570 | <<locked>> | 90% | 60,321 psi | 90% | 3196 fps | 99.7% |
| Winchester StaBALL HD | <<locked>> | 82% | 59,132 psi | 89% | 3064 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 82% | 57,943 psi | 87% | 2995 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% | 54,201 psi | 81% | 2907 fps | 100% |
| Accurate 8700 | <<locked>> | 90% | 41,292 psi | 62% | 2769 fps | 95.9% |
| ADI AR 2213 | <<locked>> | 80% | 53,867 psi | 81% | 3015 fps | 100% |
| ADI AR 2217 | <<locked>> | 80% | 40,828 psi | 61% | 2766 fps | 99.2% |
| ADI AR 2218 | 91.1 gr | 82% | 37,782 psi | 57% | 2772 fps | 95% |
| ADI AR 2225 | <<locked>> | 80% | 38,159 psi | 57% | 2736 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 54,563 psi | 82% | 3009 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 80% | 53,200 psi | 80% | 2910 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 47,369 psi | 71% | 2881 fps | 100% |
| Alliant Reloder-33 | 90.6 gr | 80% | 39,450 psi | 59% | 2769 fps | 95.7% |
| Alliant Reloder-50 | <<locked>> | 84% | 40,118 psi | 60% | 2772 fps | 95.3% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 50,357 psi | 75% | 2917 fps | 98.8% |
| Bofors RP15 | <<locked>> | 80% | 50,836 psi | 76% | 2946 fps | 100% |
| Bofors RP30 | <<locked>> | 80% | 44,353 psi | 66% | 2841 fps | 99.7% |
| Bofors RP5 | <<locked>> | 80% | 54,563 psi | 82% | 3009 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 44,527 psi | 67% | 2838 fps | 99.9% |
| Hodgdon H4831 | <<locked>> | 80% | 55,767 psi | 84% | 2999 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 80% | 54,868 psi | 82% | 2986 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 80% | 47,036 psi | 71% | 2966 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,761 psi | 43% | 1772 fps | 100% |
| Hodgdon US 869 | <<locked>> | 96% | 55,840 psi | 84% | 3035 fps | 95.9% |
| IMR 4955 Enduron | <<locked>> | 80% | 55,593 psi | 83% | 2976 fps | 100% |
| IMR 7828 SSC | <<locked>> | 80% | 52,663 psi | 79% | 2999 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 82% | 47,848 psi | 72% | 2815 fps | 95.4% |
| IMR 8133 Enduron | <<locked>> | 80% | 35,665 psi | 53% | 2657 fps | 97.7% |
| Lovex D100 | <<locked>> | 88% | 52,446 psi | 79% | 2927 fps | 95.6% |
| Lovex S071 | <<locked>> | 80% | 46,746 psi | 70% | 2789 fps | 100% |
| Norma 217 | <<locked>> | 80% | 36,434 psi | 55% | 2687 fps | 99.5% |
| Ramshot Grand | <<locked>> | 80% | 54,186 psi | 81% | 3025 fps | 100% |
| Ramshot LRT | <<locked>> | 92% | 54,636 psi | 82% | 3074 fps | 95.7% |
| Ramshot Magnum | <<locked>> | 80% | 48,936 psi | 73% | 2887 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,689 psi | 45% | 1818 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 47,137 psi | 71% | 2940 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 43,279 psi | 65% | 2844 fps | 98.7% |
| Shooters World 50 BMG | <<locked>> | 88% | 52,446 psi | 79% | 2927 fps | 95.6% |
| SNPE Vectan SP 13 | <<locked>> | 88% | 40,335 psi | 60% | 2726 fps | 95.1% |
| Vihtavuori 20N29 | <<locked>> | 96% | 46,992 psi | 70% | 2881 fps | 95.6% |
| Vihtavuori N165 | <<locked>> | 80% | 51,314 psi | 77% | 2881 fps | 100% |
| Vihtavuori N170 | <<locked>> | 80% | 44,454 psi | 67% | 2785 fps | 95.9% |
| Vihtavuori N565 | <<locked>> | 80% | 48,733 psi | 73% | 2913 fps | 99.8% |
| Vihtavuori N568 | <<locked>> | 80% | 43,976 psi | 66% | 2854 fps | 98.4% |
| Vihtavuori N570 | 87.1 gr | 80% | 42,076 psi | 63% | 2848 fps | 96.2% |
| Winchester StaBALL HD | <<locked>> | 80% | 54,868 psi | 82% | 3005 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 54,186 psi | 81% | 2940 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 44 powders for 7.21 Firebird loaded with the .284 | 165gr | Remington SP Core-Lokt. ADI AR 2218 delivers the highest muzzle velocity at 3,222 fps; across all powders the maximum-charge window runs from 1,982 fps to 3,222 fps. Accurate 8700 gives the best case fill at 100 %, and 44 of the 44 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 165.0 gr projectile in 0.284" calls for a 1:12.5 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 | 165gr | Remington SP Core-Lokt 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.