Load Specifications
Load data in caliber 7.21 Firebird with .284 | 160gr | Speer Magnum Tip Soft Point bullet and 46 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-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 3100 | <<locked>> | 82% | 56,695 psi | 85% | 2982 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 58,218 psi | 87% | 3114 fps | 99.3% |
| Accurate MAGPRO | <<locked>> | 82% | 60,104 psi | 90% | 3166 fps | 100% |
| ADI AR 2213 | <<locked>> | 82% | 56,594 psi | 85% | 3097 fps | 100% |
| ADI AR 2217 | <<locked>> | 90% | 56,782 psi | 85% | 3087 fps | 100% |
| ADI AR 2218 | <<locked>> | 94% | 57,986 psi | 87% | 3235 fps | 99.8% |
| ADI AR 2225 | <<locked>> | 92% | 57,043 psi | 86% | 3110 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 82% | 57,188 psi | 86% | 3091 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 84% | 59,292 psi | 89% | 3038 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 86% | 56,797 psi | 85% | 3071 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 92% | 60,118 psi | 90% | 3205 fps | 99.7% |
| Alliant Reloder-50 | <<locked>> | 94% | 56,579 psi | 85% | 3133 fps | 99.1% |
| Baschieri & Pellagri 109 | <<locked>> | 86% | 60,176 psi | 90% | 3114 fps | 99.7% |
| Bofors RP15 | <<locked>> | 84% | 56,782 psi | 85% | 3084 fps | 100% |
| Bofors RP30 | <<locked>> | 88% | 56,811 psi | 85% | 3104 fps | 100% |
| Bofors RP5 | <<locked>> | 82% | 57,188 psi | 86% | 3091 fps | 100% |
| Hodgdon H1000 | <<locked>> | 88% | 58,015 psi | 87% | 3104 fps | 100% |
| Hodgdon H4831 | <<locked>> | 82% | 58,566 psi | 88% | 3084 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 82% | 57,653 psi | 86% | 3068 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 86% | 57,029 psi | 85% | 3176 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,232 psi | 57% | 2008 fps | 100% |
| Hodgdon US 869 | <<locked>> | 98% | 58,537 psi | 88% | 3114 fps | 96.2% |
| IMR 4955 Enduron | <<locked>> | 82% | 58,349 psi | 87% | 3054 fps | 100% |
| IMR 7828 SSC | <<locked>> | 84% | 59,277 psi | 89% | 3146 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 88% | 57,159 psi | 86% | 3015 fps | 97.2% |
| IMR 8133 Enduron | <<locked>> | 96% | 59,886 psi | 90% | 3159 fps | 100% |
| Lovex D100 | <<locked>> | 92% | 59,306 psi | 89% | 3077 fps | 96.8% |
| Lovex S071 | <<locked>> | 88% | 59,059 psi | 89% | 3018 fps | 100% |
| Norma 217 | <<locked>> | 94% | 57,798 psi | 87% | 3123 fps | 100% |
| Ramshot Grand | <<locked>> | 82% | 56,913 psi | 85% | 3107 fps | 100% |
| Ramshot LRT | <<locked>> | 94% | 57,130 psi | 86% | 3153 fps | 96% |
| Ramshot Magnum | <<locked>> | 86% | 59,712 psi | 90% | 3091 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,349 psi | 59% | 2054 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 86% | 57,798 psi | 87% | 3153 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 88% | 56,855 psi | 85% | 3130 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 92% | 59,306 psi | 89% | 3077 fps | 96.8% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 59,495 psi | 89% | 3117 fps | 99.2% |
| Vihtavuori 20N29ᴾ | <<locked>> | 100% | 52,939 psi | 79% | 3025 fps | 96.9% |
| Vihtavuori 24N41 | <<locked>> | 96% | 59,117 psi | 89% | 3127 fps | 96.2% |
| Vihtavuori N165 | <<locked>> | 84% | 57,334 psi | 86% | 3009 fps | 100% |
| Vihtavuori N170 | <<locked>> | 88% | 57,101 psi | 86% | 3054 fps | 98.5% |
| Vihtavuori N565 | <<locked>> | 86% | 58,407 psi | 88% | 3114 fps | 100% |
| Vihtavuori N568 | <<locked>> | 88% | 57,043 psi | 86% | 3133 fps | 99.9% |
| Vihtavuori N570 | <<locked>> | 90% | 58,929 psi | 88% | 3212 fps | 99.4% |
| Winchester StaBALL HD | <<locked>> | 82% | 57,464 psi | 86% | 3084 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 82% | 56,913 psi | 85% | 3018 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% | 52,997 psi | 79% | 2930 fps | 100% |
| Accurate 8700 | <<locked>> | 90% | 40,205 psi | 60% | 2779 fps | 95.2% |
| Accurate MAGPRO | <<locked>> | 80% | 56,086 psi | 84% | 3104 fps | 99.9% |
| ADI AR 2213 | <<locked>> | 80% | 52,605 psi | 79% | 3031 fps | 100% |
| ADI AR 2217 | <<locked>> | 80% | 39,726 psi | 60% | 2776 fps | 98.8% |
| ADI AR 2218 | 93.4 gr | 84% | 39,668 psi | 59% | 2854 fps | 95.5% |
| ADI AR 2225 | <<locked>> | 80% | 37,188 psi | 56% | 2749 fps | 99.9% |
| Alliant Reloder-22 | <<locked>> | 80% | 53,316 psi | 80% | 3028 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 80% | 52,025 psi | 78% | 2933 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 46,325 psi | 69% | 2900 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 82% | 41,379 psi | 62% | 2848 fps | 96% |
| Alliant Reloder-50 | 97.1 gr | 86% | 41,959 psi | 63% | 2848 fps | 95.6% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 49,487 psi | 74% | 2933 fps | 98.5% |
| Bofors RP15 | <<locked>> | 80% | 49,690 psi | 74% | 2966 fps | 100% |
| Bofors RP30 | <<locked>> | 80% | 43,192 psi | 65% | 2854 fps | 99.4% |
| Bofors RP5 | <<locked>> | 80% | 53,316 psi | 80% | 3028 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 43,497 psi | 65% | 2854 fps | 99.7% |
| Hodgdon H4831 | <<locked>> | 80% | 54,752 psi | 82% | 3022 fps | 99.9% |
| Hodgdon H4831 SC | <<locked>> | 80% | 53,722 psi | 81% | 3005 fps | 99.9% |
| Hodgdon Retumbo | <<locked>> | 80% | 45,847 psi | 69% | 2982 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,674 psi | 43% | 1798 fps | 100% |
| Hodgdon US 869 | <<locked>> | 96% | 54,563 psi | 82% | 3045 fps | 95.2% |
| IMR 4955 Enduron | <<locked>> | 80% | 54,708 psi | 82% | 2995 fps | 100% |
| IMR 7828 SSC | <<locked>> | 80% | 51,590 psi | 77% | 3022 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 84% | 50,285 psi | 75% | 2894 fps | 95.7% |
| IMR 8133 Enduron | <<locked>> | 80% | 34,635 psi | 52% | 2667 fps | 97.1% |
| Lovex D100 | <<locked>> | 90% | 55,100 psi | 83% | 3005 fps | 95.9% |
| Lovex S071 | <<locked>> | 80% | 45,847 psi | 69% | 2808 fps | 100% |
| Norma 217 | <<locked>> | 80% | 35,476 psi | 53% | 2697 fps | 99.1% |
| Ramshot Grand | <<locked>> | 80% | 52,808 psi | 79% | 3041 fps | 100% |
| Ramshot LRT | <<locked>> | 92% | 53,200 psi | 80% | 3081 fps | 95% |
| Ramshot Magnum | <<locked>> | 80% | 47,834 psi | 72% | 2904 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,602 psi | 44% | 1841 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 45,890 psi | 69% | 2956 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 42,047 psi | 63% | 2851 fps | 98.2% |
| Shooters World 50 BMG | <<locked>> | 90% | 55,100 psi | 83% | 3005 fps | 95.9% |
| SNPE Vectan SP 13 | <<locked>> | 90% | 42,148 psi | 63% | 2799 fps | 95.4% |
| Vihtavuori 20N29 | <<locked>> | 98% | 49,226 psi | 74% | 2956 fps | 95.9% |
| Vihtavuori 24N41 | <<locked>> | 94% | 55,042 psi | 83% | 3058 fps | 95.3% |
| Vihtavuori N165 | <<locked>> | 80% | 50,241 psi | 75% | 2897 fps | 100% |
| Vihtavuori N170 | <<locked>> | 80% | 43,569 psi | 65% | 2802 fps | 95.3% |
| Vihtavuori N565 | <<locked>> | 80% | 47,703 psi | 72% | 2927 fps | 99.6% |
| Vihtavuori N568 | <<locked>> | 80% | 42,801 psi | 64% | 2867 fps | 97.9% |
| Vihtavuori N570 | 87.2 gr | 80% | 41,031 psi | 62% | 2858 fps | 95.4% |
| Winchester StaBALL HD | <<locked>> | 80% | 53,461 psi | 80% | 3028 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 53,011 psi | 79% | 2956 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 47 powders for 7.21 Firebird loaded with the .284 | 160gr | Speer Magnum Tip Soft Point. ADI AR 2218 delivers the highest muzzle velocity at 3,235 fps; across all powders the maximum-charge window runs from 2,008 fps to 3,235 fps. Accurate 8700 gives the best case fill at 100 %, and 47 of the 47 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 160.0 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-50 rank at the top here: for 7.21 Firebird with the .284 | 160gr | Speer Magnum Tip 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.