Load Specifications
Load data in caliber 7.21 Firebird with .284 | 150gr | Osprey Virtus bullet and 52 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>> | 86% | 58,392 psi | 88% | 3094 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 50,676 psi | 76% | 3068 fps | 97.5% |
| Accurate MAGPRO | <<locked>> | 84% | 57,885 psi | 87% | 3219 fps | 99.8% |
| ADI AR 2209 | <<locked>> | 84% | 59,625 psi | 89% | 3196 fps | 100% |
| ADI AR 2213 | <<locked>> | 86% | 58,537 psi | 88% | 3215 fps | 100% |
| ADI AR 2217 | <<locked>> | 94% | 58,102 psi | 87% | 3196 fps | 100% |
| ADI AR 2218 | <<locked>> | 98% | 59,132 psi | 89% | 3337 fps | 99.5% |
| ADI AR 2225 | <<locked>> | 96% | 57,798 psi | 87% | 3215 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 84% | 59,146 psi | 89% | 3182 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 86% | 58,914 psi | 88% | 3205 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 86% | 57,087 psi | 86% | 3100 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 90% | 58,044 psi | 87% | 3182 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 82% | 58,160 psi | 87% | 3192 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 94% | 56,826 psi | 85% | 3235 fps | 99% |
| Alliant Reloder-50 | <<locked>> | 98% | 56,884 psi | 85% | 3225 fps | 98.6% |
| Baschieri & Pellagri 109 | <<locked>> | 88% | 58,726 psi | 88% | 3173 fps | 99.3% |
| Bofors RP15 | <<locked>> | 88% | 58,276 psi | 87% | 3196 fps | 100% |
| Bofors RP30 | <<locked>> | 92% | 57,783 psi | 87% | 3205 fps | 100% |
| Bofors RP5 | <<locked>> | 86% | 58,914 psi | 88% | 3205 fps | 100% |
| Hodgdon H1000 | <<locked>> | 92% | 59,785 psi | 90% | 3219 fps | 100% |
| Hodgdon H4831 | <<locked>> | 84% | 57,000 psi | 85% | 3140 fps | 99.9% |
| Hodgdon H4831 SC | <<locked>> | 86% | 59,915 psi | 90% | 3186 fps | 100% |
| Hodgdon Hybrid 100V | <<locked>> | 82% | 59,669 psi | 89% | 3084 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 90% | 57,870 psi | 87% | 3284 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,855 psi | 57% | 2051 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 84% | 57,072 psi | 86% | 3117 fps | 99.9% |
| IMR 7828 SSC | <<locked>> | 86% | 57,174 psi | 86% | 3202 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 92% | 59,567 psi | 89% | 3123 fps | 96.8% |
| IMR 8133 Enduron | <<locked>> | 98% | 56,391 psi | 85% | 3199 fps | 100% |
| Lovex S071 | <<locked>> | 90% | 56,652 psi | 85% | 3071 fps | 100% |
| Norma 217 | <<locked>> | 98% | 58,044 psi | 87% | 3219 fps | 100% |
| Norma MRP | <<locked>> | 84% | 59,393 psi | 89% | 3222 fps | 100% |
| Ramshot Grand | <<locked>> | 86% | 58,740 psi | 88% | 3225 fps | 100% |
| Ramshot Magnum | <<locked>> | 88% | 57,101 psi | 86% | 3140 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,928 psi | 58% | 2100 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 90% | 58,958 psi | 88% | 3264 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 92% | 57,914 psi | 87% | 3235 fps | 99.9% |
| Rottweil R 904 | <<locked>> | 84% | 59,799 psi | 90% | 3163 fps | 100% |
| Rottweil R 905 | <<locked>> | 84% | 58,914 psi | 88% | 3173 fps | 100% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 52,431 psi | 79% | 3077 fps | 97.5% |
| SNPE Vectan Tubal 8000 | <<locked>> | 84% | 58,537 psi | 88% | 3169 fps | 100% |
| Somchem S361 | <<locked>> | 82% | 57,261 psi | 86% | 3087 fps | 99.9% |
| Somchem S385 | <<locked>> | 84% | 59,117 psi | 89% | 3136 fps | 100% |
| Vihtavuori N165 | <<locked>> | 88% | 59,393 psi | 89% | 3123 fps | 100% |
| Vihtavuori N170 | <<locked>> | 92% | 58,943 psi | 88% | 3159 fps | 98.1% |
| Vihtavuori N555 | <<locked>> | 84% | 58,581 psi | 88% | 3127 fps | 100% |
| Vihtavuori N560 | <<locked>> | 84% | 58,639 psi | 88% | 3228 fps | 100% |
| Vihtavuori N565 | <<locked>> | 90% | 59,915 psi | 90% | 3222 fps | 100% |
| Vihtavuori N568 | <<locked>> | 92% | 58,233 psi | 87% | 3238 fps | 99.8% |
| Vihtavuori N570 | <<locked>> | 94% | 59,944 psi | 90% | 3314 fps | 99.1% |
| Winchester StaBALL HD | <<locked>> | 86% | 58,378 psi | 88% | 3196 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 86% | 59,292 psi | 89% | 3136 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% | 47,442 psi | 71% | 2923 fps | 100% |
| Accurate 8700 | <<locked>> | 96% | 43,482 psi | 65% | 2927 fps | 95.4% |
| Accurate MAGPRO | <<locked>> | 80% | 50,067 psi | 75% | 3081 fps | 99% |
| ADI AR 2209 | <<locked>> | 80% | 52,040 psi | 78% | 3071 fps | 100% |
| ADI AR 2213 | <<locked>> | 80% | 47,297 psi | 71% | 3018 fps | 99.3% |
| ADI AR 2217 | <<locked>> | 80% | 35,128 psi | 53% | 2740 fps | 96.6% |
| ADI AR 2218 | 96.7 gr | 90% | 43,453 psi | 65% | 3022 fps | 96% |
| ADI AR 2225 | <<locked>> | 80% | 32,387 psi | 49% | 2703 fps | 98.5% |
| Alliant Reloder-19 | <<locked>> | 80% | 51,706 psi | 78% | 3061 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 47,935 psi | 72% | 3018 fps | 99.8% |
| Alliant Reloder-23 | <<locked>> | 80% | 46,644 psi | 70% | 2936 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 40,814 psi | 61% | 2884 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 80% | 53,853 psi | 81% | 3127 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 86% | 41,640 psi | 62% | 2933 fps | 95.2% |
| Alliant Reloder-50 | <<locked>> | 92% | 45,078 psi | 68% | 2999 fps | 95.8% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 45,020 psi | 67% | 2920 fps | 96.7% |
| Bofors RP15 | <<locked>> | 80% | 44,628 psi | 67% | 2949 fps | 99.4% |
| Bofors RP30 | <<locked>> | 80% | 37,913 psi | 57% | 2815 fps | 97.6% |
| Bofors RP5 | <<locked>> | 80% | 47,935 psi | 72% | 3018 fps | 99.8% |
| Hodgdon H1000 | <<locked>> | 80% | 38,276 psi | 57% | 2822 fps | 98.3% |
| Hodgdon H4831 | <<locked>> | 80% | 49,574 psi | 74% | 3012 fps | 99.2% |
| Hodgdon H4831 SC | <<locked>> | 80% | 48,747 psi | 73% | 2995 fps | 99.1% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 55,796 psi | 84% | 3028 fps | 100% |
| Hodgdon Retumbo | 81.2 gr | 80% | 39,958 psi | 60% | 2946 fps | 99.5% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,413 psi | 43% | 1837 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 50,169 psi | 75% | 2995 fps | 99.4% |
| IMR 7828 SSC | <<locked>> | 80% | 46,093 psi | 69% | 3002 fps | 99.1% |
| IMR 7977 Enduron | <<locked>> | 88% | 52,199 psi | 78% | 3002 fps | 95.2% |
| IMR 8133 Enduron | <<locked>> | 82% | 32,111 psi | 48% | 2677 fps | 95% |
| Lovex S071 | <<locked>> | 80% | 40,698 psi | 61% | 2789 fps | 99.9% |
| Norma 217 | <<locked>> | 80% | 30,153 psi | 45% | 2635 fps | 96.4% |
| Norma MRP | <<locked>> | 80% | 51,285 psi | 77% | 3091 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 46,673 psi | 70% | 3015 fps | 99.4% |
| Ramshot Magnum | <<locked>> | 80% | 42,032 psi | 63% | 2877 fps | 99.7% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,138 psi | 44% | 1880 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 39,610 psi | 59% | 2917 fps | 99.9% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 36,289 psi | 54% | 2795 fps | 95.4% |
| Rottweil R 904 | <<locked>> | 80% | 52,402 psi | 79% | 3041 fps | 99.8% |
| Rottweil R 905 | <<locked>> | 80% | 51,445 psi | 77% | 3051 fps | 100% |
| SNPE Vectan SP 13 | <<locked>> | 96% | 45,527 psi | 68% | 2946 fps | 95.6% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 51,097 psi | 77% | 3048 fps | 100% |
| Somchem S361 | <<locked>> | 80% | 53,577 psi | 80% | 3028 fps | 99.6% |
| Somchem S385 | <<locked>> | 80% | 51,692 psi | 77% | 3018 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 45,310 psi | 68% | 2890 fps | 99.8% |
| Vihtavuori N170 | <<locked>> | 86% | 47,921 psi | 72% | 2966 fps | 95.7% |
| Vihtavuori N555 | <<locked>> | 80% | 51,387 psi | 77% | 3018 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 50,720 psi | 76% | 3094 fps | 99.4% |
| Vihtavuori N565 | <<locked>> | 80% | 42,177 psi | 63% | 2894 fps | 98.1% |
| Vihtavuori N568 | <<locked>> | 80% | 37,376 psi | 56% | 2818 fps | 95.2% |
| Vihtavuori N570 | 90.6 gr | 86% | 44,628 psi | 67% | 3022 fps | 95.8% |
| Winchester StaBALL HD | <<locked>> | 80% | 46,456 psi | 70% | 3012 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 48,008 psi | 72% | 2953 fps | 99.8% |
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 52 powders for 7.21 Firebird loaded with the .284 | 150gr | Osprey Virtus. ADI AR 2218 delivers the highest muzzle velocity at 3,337 fps; across all powders the maximum-charge window runs from 2,051 fps to 3,337 fps. Accurate 8700 gives the best case fill at 100 %, and 52 of the 52 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 1:9.0 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, Hodgdon Retumbo, Vihtavuori N570 rank at the top here: for 7.21 Firebird with the .284 | 150gr | Osprey Virtus 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.