Load Specifications
Load data in caliber 7.21 Firebird with .284 | 160gr | Sierra Tipped MatchKing bullet and 53 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>> | 84% | 58,987 psi | 88% | 3015 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 55,753 psi | 84% | 3077 fps | 98.9% |
| Accurate MAGPRO | <<locked>> | 82% | 58,349 psi | 87% | 3143 fps | 100% |
| ADI AR 2209 | <<locked>> | 82% | 59,582 psi | 89% | 3107 fps | 100% |
| ADI AR 2213 | <<locked>> | 84% | 58,769 psi | 88% | 3133 fps | 100% |
| ADI AR 2217 | <<locked>> | 92% | 58,798 psi | 88% | 3120 fps | 100% |
| ADI AR 2218 | <<locked>> | 96% | 59,988 psi | 90% | 3271 fps | 99.9% |
| ADI AR 2225 | <<locked>> | 94% | 58,784 psi | 88% | 3143 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 82% | 59,016 psi | 88% | 3094 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 84% | 59,306 psi | 89% | 3123 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 84% | 57,551 psi | 86% | 3018 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 88% | 58,711 psi | 88% | 3100 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 92% | 57,754 psi | 87% | 3169 fps | 99.5% |
| Alliant Reloder-50 | <<locked>> | 96% | 58,320 psi | 87% | 3169 fps | 99.3% |
| Baschieri & Pellagri 109 | <<locked>> | 86% | 58,494 psi | 88% | 3091 fps | 99.6% |
| Bofors RP15 | <<locked>> | 86% | 58,856 psi | 88% | 3117 fps | 100% |
| Bofors RP30 | <<locked>> | 90% | 58,827 psi | 88% | 3136 fps | 100% |
| Bofors RP5 | <<locked>> | 84% | 59,306 psi | 89% | 3123 fps | 100% |
| Hodgdon H1000 | <<locked>> | 90% | 60,234 psi | 90% | 3136 fps | 100% |
| Hodgdon H4831 | <<locked>> | 82% | 57,014 psi | 85% | 3058 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 84% | 59,915 psi | 90% | 3104 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 88% | 58,914 psi | 88% | 3209 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,130 psi | 57% | 1998 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 82% | 56,884 psi | 85% | 3031 fps | 100% |
| IMR 7828 SSC | <<locked>> | 84% | 57,348 psi | 86% | 3117 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 90% | 59,451 psi | 89% | 3051 fps | 97.5% |
| IMR 8133 Enduron | <<locked>> | 96% | 57,624 psi | 86% | 3130 fps | 100% |
| Lovex D100 | <<locked>> | 92% | 57,348 psi | 86% | 3045 fps | 96.2% |
| Lovex S071 | <<locked>> | 88% | 57,464 psi | 86% | 2995 fps | 100% |
| Norma 217 | <<locked>> | 96% | 59,509 psi | 89% | 3153 fps | 100% |
| Norma MRP | <<locked>> | 82% | 59,727 psi | 90% | 3136 fps | 100% |
| Ramshot Grand | <<locked>> | 84% | 59,146 psi | 89% | 3143 fps | 100% |
| Ramshot LRT | <<locked>> | 96% | 59,234 psi | 89% | 3189 fps | 96.4% |
| Ramshot Magnum | <<locked>> | 86% | 57,580 psi | 86% | 3064 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,262 psi | 59% | 2044 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 88% | 59,973 psi | 90% | 3189 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 90% | 58,929 psi | 88% | 3169 fps | 100% |
| Rottweil R 904 | <<locked>> | 82% | 59,582 psi | 89% | 3074 fps | 100% |
| Rottweil R 905 | <<locked>> | 82% | 59,088 psi | 89% | 3087 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 92% | 57,348 psi | 86% | 3045 fps | 96.2% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 57,305 psi | 86% | 3084 fps | 98.9% |
| SNPE Vectan Tubal 8000 | <<locked>> | 82% | 58,726 psi | 88% | 3087 fps | 100% |
| Somchem S385 | <<locked>> | 82% | 59,161 psi | 89% | 3051 fps | 100% |
| Vihtavuori 20N29ᴾ | <<locked>> | 100% | 50,676 psi | 76% | 2989 fps | 96.2% |
| Vihtavuori N165 | <<locked>> | 86% | 59,553 psi | 89% | 3041 fps | 100% |
| Vihtavuori N170 | <<locked>> | 90% | 59,161 psi | 89% | 3087 fps | 98.7% |
| Vihtavuori N555 | <<locked>> | 82% | 59,146 psi | 89% | 3048 fps | 100% |
| Vihtavuori N560 | <<locked>> | 82% | 58,900 psi | 88% | 3150 fps | 100% |
| Vihtavuori N565 | <<locked>> | 86% | 56,695 psi | 85% | 3087 fps | 100% |
| Vihtavuori N568 | <<locked>> | 90% | 58,987 psi | 88% | 3169 fps | 100% |
| Vihtavuori N570 | <<locked>> | 90% | 56,623 psi | 85% | 3176 fps | 99.1% |
| Winchester StaBALL HD | <<locked>> | 84% | 59,669 psi | 89% | 3120 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 84% | 59,176 psi | 89% | 3051 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% | 51,561 psi | 77% | 2907 fps | 100% |
| Accurate 8700 | <<locked>> | 92% | 41,539 psi | 62% | 2812 fps | 95.6% |
| Accurate MAGPRO | <<locked>> | 80% | 54,273 psi | 81% | 3077 fps | 99.8% |
| ADI AR 2209 | <<locked>> | 80% | 55,753 psi | 84% | 3051 fps | 100% |
| ADI AR 2213 | <<locked>> | 80% | 51,140 psi | 77% | 3009 fps | 99.9% |
| ADI AR 2217 | <<locked>> | 80% | 38,392 psi | 58% | 2749 fps | 98.5% |
| ADI AR 2218 | 93 gr | 86% | 41,176 psi | 62% | 2897 fps | 96% |
| ADI AR 2225 | <<locked>> | 80% | 35,868 psi | 54% | 2726 fps | 99.8% |
| Alliant Reloder-19 | <<locked>> | 80% | 55,376 psi | 83% | 3038 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 51,866 psi | 78% | 3005 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 80% | 50,444 psi | 76% | 2913 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 44,773 psi | 67% | 2881 fps | 100% |
| Alliant Reloder-33 | 90.3 gr | 82% | 39,726 psi | 60% | 2815 fps | 95.3% |
| Alliant Reloder-50 | <<locked>> | 88% | 43,308 psi | 65% | 2884 fps | 96% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 48,095 psi | 72% | 2910 fps | 98.1% |
| Bofors RP15 | <<locked>> | 80% | 48,225 psi | 72% | 2940 fps | 100% |
| Bofors RP30 | <<locked>> | 80% | 41,800 psi | 63% | 2828 fps | 99.1% |
| Bofors RP5 | <<locked>> | 80% | 51,866 psi | 78% | 3005 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 41,930 psi | 63% | 2828 fps | 99.5% |
| Hodgdon H4831 | <<locked>> | 80% | 53,229 psi | 80% | 2995 fps | 99.8% |
| Hodgdon H4831 SC | <<locked>> | 80% | 52,344 psi | 78% | 2982 fps | 99.8% |
| Hodgdon Retumbo | <<locked>> | 80% | 44,135 psi | 66% | 2956 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,732 psi | 43% | 1791 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 53,432 psi | 80% | 2976 fps | 99.9% |
| IMR 7828 SSC | <<locked>> | 80% | 50,053 psi | 75% | 2995 fps | 99.9% |
| IMR 7977 Enduron | <<locked>> | 84% | 48,849 psi | 73% | 2867 fps | 95.1% |
| IMR 8133 Enduron | <<locked>> | 80% | 33,301 psi | 50% | 2638 fps | 96.5% |
| Lovex D100 | <<locked>> | 90% | 53,388 psi | 80% | 2976 fps | 95.3% |
| Lovex S071 | <<locked>> | 80% | 44,527 psi | 67% | 2785 fps | 100% |
| Norma 217 | <<locked>> | 80% | 34,040 psi | 51% | 2671 fps | 98.7% |
| Norma MRP | <<locked>> | 80% | 55,564 psi | 83% | 3077 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 51,010 psi | 76% | 3015 fps | 100% |
| Ramshot LRT | <<locked>> | 94% | 55,013 psi | 82% | 3117 fps | 95.3% |
| Ramshot Magnum | <<locked>> | 80% | 46,122 psi | 69% | 2877 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,515 psi | 44% | 1834 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 44,034 psi | 66% | 2930 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 40,437 psi | 61% | 2822 fps | 97.7% |
| Rottweil R 904 | <<locked>> | 80% | 55,869 psi | 84% | 3018 fps | 100% |
| Rottweil R 905 | <<locked>> | 80% | 55,332 psi | 83% | 3031 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 90% | 53,388 psi | 80% | 2976 fps | 95.3% |
| SNPE Vectan SP 13 | <<locked>> | 92% | 43,497 psi | 65% | 2831 fps | 95.8% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 54,969 psi | 82% | 3028 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 55,535 psi | 83% | 2995 fps | 100% |
| Vihtavuori 20N29 | <<locked>> | 98% | 47,195 psi | 71% | 2920 fps | 95.2% |
| Vihtavuori N165 | <<locked>> | 80% | 48,892 psi | 73% | 2877 fps | 100% |
| Vihtavuori N170 | <<locked>> | 82% | 45,266 psi | 68% | 2838 fps | 95.7% |
| Vihtavuori N555 | <<locked>> | 80% | 55,448 psi | 83% | 2992 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 54,824 psi | 82% | 3084 fps | 100% |
| Vihtavuori N565 | <<locked>> | 80% | 46,166 psi | 69% | 2904 fps | 99.3% |
| Vihtavuori N568 | <<locked>> | 80% | 41,292 psi | 62% | 2838 fps | 97.4% |
| Vihtavuori N570 | 86.9 gr | 82% | 42,496 psi | 64% | 2897 fps | 95.8% |
| Winchester StaBALL HD | <<locked>> | 80% | 51,430 psi | 77% | 3005 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 51,677 psi | 77% | 2936 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 53 powders for 7.21 Firebird loaded with the .284 | 160gr | Sierra Tipped MatchKing. ADI AR 2218 delivers the highest muzzle velocity at 3,271 fps; across all powders the maximum-charge window runs from 1,998 fps to 3,271 fps. Accurate 8700 gives the best case fill at 100 %, and 53 of the 53 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 1:10.0 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 | 160gr | Sierra Tipped MatchKing 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.