Load Specifications
Load data in caliber 7.21 Firebird with .284 | 150gr | Sierra MatchKing bullet and 50 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are ADI AR 2218, Hodgdon Retumbo and Vihtavuori N570.
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% | 58,088 psi | 87% | 3087 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 54,839 psi | 82% | 3133 fps | 98.4% |
| Accurate MAGPRO | <<locked>> | 82% | 57,435 psi | 86% | 3205 fps | 99.8% |
| ADI AR 2209 | <<locked>> | 82% | 58,639 psi | 88% | 3176 fps | 100% |
| ADI AR 2213 | <<locked>> | 84% | 57,783 psi | 87% | 3202 fps | 100% |
| ADI AR 2217 | <<locked>> | 92% | 57,798 psi | 87% | 3186 fps | 100% |
| ADI AR 2218 | <<locked>> | 96% | 58,900 psi | 88% | 3330 fps | 99.6% |
| ADI AR 2225 | <<locked>> | 94% | 57,957 psi | 87% | 3212 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 82% | 58,291 psi | 87% | 3166 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 84% | 58,320 psi | 87% | 3192 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 84% | 56,753 psi | 85% | 3091 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 88% | 57,943 psi | 87% | 3176 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 92% | 56,884 psi | 85% | 3228 fps | 99.1% |
| Alliant Reloder-50 | <<locked>> | 96% | 57,392 psi | 86% | 3228 fps | 98.8% |
| Baschieri & Pellagri 109 | <<locked>> | 86% | 57,914 psi | 87% | 3159 fps | 99.3% |
| Bofors RP15 | <<locked>> | 86% | 57,885 psi | 87% | 3186 fps | 100% |
| Bofors RP30 | <<locked>> | 90% | 57,725 psi | 87% | 3199 fps | 100% |
| Bofors RP5 | <<locked>> | 84% | 58,320 psi | 87% | 3192 fps | 100% |
| Hodgdon H1000 | <<locked>> | 90% | 59,277 psi | 89% | 3205 fps | 100% |
| Hodgdon H4831 | <<locked>> | 84% | 60,133 psi | 90% | 3189 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 84% | 58,987 psi | 88% | 3169 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 88% | 57,928 psi | 87% | 3278 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,116 psi | 57% | 2064 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 84% | 59,814 psi | 90% | 3159 fps | 100% |
| IMR 7828 SSC | <<locked>> | 84% | 56,608 psi | 85% | 3189 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 90% | 58,624 psi | 88% | 3114 fps | 96.9% |
| IMR 8133 Enduron | <<locked>> | 96% | 56,681 psi | 85% | 3196 fps | 100% |
| Lovex S071 | <<locked>> | 90% | 60,176 psi | 90% | 3117 fps | 100% |
| Norma 217 | <<locked>> | 96% | 58,421 psi | 88% | 3215 fps | 100% |
| Norma MRP | <<locked>> | 82% | 58,711 psi | 88% | 3209 fps | 100% |
| Ramshot Grand | <<locked>> | 84% | 58,146 psi | 87% | 3209 fps | 100% |
| Ramshot Magnum | <<locked>> | 86% | 56,623 psi | 85% | 3127 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,204 psi | 59% | 2113 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 88% | 58,827 psi | 88% | 3255 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 90% | 57,928 psi | 87% | 3228 fps | 99.9% |
| Rottweil R 904 | <<locked>> | 82% | 58,769 psi | 88% | 3146 fps | 100% |
| Rottweil R 905 | <<locked>> | 82% | 58,146 psi | 87% | 3159 fps | 100% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 56,536 psi | 85% | 3146 fps | 98.4% |
| SNPE Vectan Tubal 8000 | <<locked>> | 82% | 57,783 psi | 87% | 3156 fps | 100% |
| Somchem S361 | <<locked>> | 82% | 60,336 psi | 90% | 3136 fps | 100% |
| Somchem S385 | <<locked>> | 82% | 58,407 psi | 88% | 3123 fps | 100% |
| Vihtavuori N165 | <<locked>> | 86% | 58,798 psi | 88% | 3114 fps | 100% |
| Vihtavuori N170 | <<locked>> | 90% | 58,363 psi | 87% | 3153 fps | 98.2% |
| Vihtavuori N555 | <<locked>> | 82% | 58,276 psi | 87% | 3120 fps | 100% |
| Vihtavuori N560 | <<locked>> | 82% | 57,870 psi | 87% | 3215 fps | 100% |
| Vihtavuori N565 | <<locked>> | 88% | 59,756 psi | 90% | 3215 fps | 100% |
| Vihtavuori N568 | <<locked>> | 90% | 58,001 psi | 87% | 3232 fps | 99.8% |
| Vihtavuori N570 | <<locked>> | 92% | 59,843 psi | 90% | 3307 fps | 99.2% |
| Winchester StaBALL HD | <<locked>> | 84% | 58,349 psi | 87% | 3186 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 84% | 58,407 psi | 88% | 3120 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% | 50,778 psi | 76% | 2972 fps | 100% |
| Accurate 8700 | <<locked>> | 94% | 43,845 psi | 66% | 2927 fps | 95.7% |
| Accurate MAGPRO | <<locked>> | 80% | 53,505 psi | 80% | 3140 fps | 99.5% |
| ADI AR 2209 | <<locked>> | 80% | 54,969 psi | 82% | 3120 fps | 100% |
| ADI AR 2213 | <<locked>> | 80% | 50,256 psi | 75% | 3071 fps | 99.7% |
| ADI AR 2217 | <<locked>> | 80% | 37,710 psi | 57% | 2802 fps | 97.8% |
| ADI AR 2218 | 97.9 gr | 88% | 43,627 psi | 65% | 3022 fps | 96.3% |
| ADI AR 2225 | <<locked>> | 80% | 35,128 psi | 53% | 2776 fps | 99.3% |
| Alliant Reloder-19 | <<locked>> | 80% | 54,578 psi | 82% | 3107 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 50,995 psi | 76% | 3071 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 80% | 49,719 psi | 75% | 2982 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 43,976 psi | 66% | 2943 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 84% | 42,018 psi | 63% | 2936 fps | 95.5% |
| Alliant Reloder-50 | <<locked>> | 88% | 42,467 psi | 64% | 2930 fps | 95% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 47,398 psi | 71% | 2966 fps | 97.5% |
| Bofors RP15 | <<locked>> | 80% | 47,514 psi | 71% | 3005 fps | 99.8% |
| Bofors RP30 | <<locked>> | 80% | 41,031 psi | 62% | 2884 fps | 98.6% |
| Bofors RP5 | <<locked>> | 80% | 50,995 psi | 76% | 3071 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 41,118 psi | 62% | 2881 fps | 99.1% |
| Hodgdon H4831 | <<locked>> | 80% | 52,547 psi | 79% | 3064 fps | 99.6% |
| Hodgdon H4831 SC | <<locked>> | 80% | 51,561 psi | 77% | 3045 fps | 99.5% |
| Hodgdon Retumbo | 84 gr | 80% | 43,192 psi | 65% | 3012 fps | 99.9% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,572 psi | 43% | 1850 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 52,736 psi | 79% | 3045 fps | 99.7% |
| IMR 7828 SSC | <<locked>> | 80% | 49,168 psi | 74% | 3058 fps | 99.6% |
| IMR 7977 Enduron | <<locked>> | 86% | 51,532 psi | 77% | 2989 fps | 95.3% |
| IMR 8133 Enduron | <<locked>> | 80% | 32,663 psi | 49% | 2684 fps | 95.5% |
| Lovex S071 | <<locked>> | 80% | 43,830 psi | 66% | 2848 fps | 100% |
| Norma 217 | <<locked>> | 80% | 33,199 psi | 50% | 2713 fps | 97.9% |
| Norma MRP | <<locked>> | 80% | 54,694 psi | 82% | 3143 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 50,140 psi | 75% | 3074 fps | 99.8% |
| Ramshot Magnum | <<locked>> | 80% | 45,252 psi | 68% | 2936 fps | 99.9% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,472 psi | 44% | 1896 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 43,134 psi | 65% | 2986 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 39,653 psi | 59% | 2871 fps | 96.9% |
| Rottweil R 904 | <<locked>> | 80% | 55,013 psi | 82% | 3084 fps | 100% |
| Rottweil R 905 | <<locked>> | 80% | 54,520 psi | 82% | 3104 fps | 100% |
| SNPE Vectan SP 13 | <<locked>> | 94% | 45,905 psi | 69% | 2949 fps | 95.9% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 54,201 psi | 81% | 3097 fps | 100% |
| Somchem S361 | <<locked>> | 80% | 56,463 psi | 85% | 3074 fps | 99.9% |
| Somchem S385 | <<locked>> | 80% | 54,694 psi | 82% | 3064 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 48,167 psi | 72% | 2940 fps | 100% |
| Vihtavuori N170 | <<locked>> | 84% | 47,688 psi | 71% | 2956 fps | 95.8% |
| Vihtavuori N555 | <<locked>> | 80% | 54,694 psi | 82% | 3064 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 53,969 psi | 81% | 3150 fps | 99.8% |
| Vihtavuori N565 | <<locked>> | 80% | 45,455 psi | 68% | 2959 fps | 98.9% |
| Vihtavuori N568 | <<locked>> | 80% | 40,524 psi | 61% | 2887 fps | 96.6% |
| Vihtavuori N570 | 91.5 gr | 84% | 44,788 psi | 67% | 3018 fps | 96% |
| Winchester StaBALL HD | <<locked>> | 80% | 50,270 psi | 75% | 3068 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 50,836 psi | 76% | 2999 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 50 powders for 7.21 Firebird loaded with the .284 | 150gr | Sierra MatchKing. ADI AR 2218 delivers the highest muzzle velocity at 3,330 fps; across all powders the maximum-charge window runs from 2,064 fps to 3,330 fps. Accurate 8700 gives the best case fill at 100 %, and 50 of the 50 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 150.0 gr projectile in 0.284" calls for a 1:11.5 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, Hodgdon Retumbo, Vihtavuori N570 rank at the top here: for 7.21 Firebird with the .284 | 150gr | Sierra 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.