Load Specifications
Load data in caliber 7.21 Firebird with .284 | 150gr | Swift Scirocco bullet and 51 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 Hodgdon Retumbo.
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% | 56,463 psi | 85% | 3064 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 52,707 psi | 79% | 3100 fps | 97.9% |
| Accurate MAGPRO | <<locked>> | 84% | 59,741 psi | 90% | 3245 fps | 99.9% |
| ADI AR 2209 | <<locked>> | 82% | 57,145 psi | 86% | 3153 fps | 100% |
| ADI AR 2213 | <<locked>> | 86% | 60,205 psi | 90% | 3238 fps | 100% |
| ADI AR 2217 | <<locked>> | 94% | 60,046 psi | 90% | 3222 fps | 100% |
| ADI AR 2218 | <<locked>> | 96% | 56,768 psi | 85% | 3294 fps | 99.3% |
| ADI AR 2225 | <<locked>> | 96% | 59,901 psi | 90% | 3241 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 82% | 56,840 psi | 85% | 3143 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 84% | 56,884 psi | 85% | 3169 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 86% | 58,943 psi | 88% | 3123 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 90% | 59,930 psi | 90% | 3205 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 82% | 60,234 psi | 90% | 3219 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 94% | 59,001 psi | 88% | 3268 fps | 99.3% |
| Alliant Reloder-50 | <<locked>> | 98% | 59,393 psi | 89% | 3264 fps | 99% |
| Baschieri & Pellagri 109 | <<locked>> | 88% | 60,234 psi | 90% | 3196 fps | 99.4% |
| Bofors RP15 | <<locked>> | 88% | 60,046 psi | 90% | 3219 fps | 100% |
| Bofors RP30 | <<locked>> | 92% | 59,944 psi | 90% | 3235 fps | 100% |
| Bofors RP5 | <<locked>> | 84% | 56,884 psi | 85% | 3169 fps | 100% |
| Hodgdon H1000 | <<locked>> | 90% | 57,203 psi | 86% | 3179 fps | 100% |
| Hodgdon H4831 | <<locked>> | 84% | 58,581 psi | 88% | 3163 fps | 99.9% |
| Hodgdon H4831 SC | <<locked>> | 84% | 57,624 psi | 86% | 3146 fps | 99.9% |
| Hodgdon Retumbo | <<locked>> | 90% | 59,857 psi | 90% | 3310 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,058 psi | 57% | 2054 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 84% | 58,508 psi | 88% | 3136 fps | 100% |
| IMR 7828 SSC | <<locked>> | 86% | 58,711 psi | 88% | 3222 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 90% | 57,174 psi | 86% | 3087 fps | 96.4% |
| IMR 8133 Enduron | <<locked>> | 98% | 58,595 psi | 88% | 3228 fps | 100% |
| Lovex S071 | <<locked>> | 90% | 58,726 psi | 88% | 3097 fps | 100% |
| Norma 217 | <<locked>> | 96% | 56,405 psi | 85% | 3192 fps | 100% |
| Norma MRP | <<locked>> | 82% | 56,971 psi | 85% | 3182 fps | 100% |
| Ramshot Grand | <<locked>> | 84% | 56,318 psi | 84% | 3182 fps | 100% |
| Ramshot Magnum | <<locked>> | 88% | 59,190 psi | 89% | 3169 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,001 psi | 58% | 2100 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 88% | 56,666 psi | 85% | 3228 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 92% | 60,220 psi | 90% | 3268 fps | 100% |
| Rottweil R 904 | <<locked>> | 82% | 57,348 psi | 86% | 3123 fps | 100% |
| Rottweil R 905 | <<locked>> | 82% | 56,797 psi | 85% | 3136 fps | 100% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 54,476 psi | 82% | 3110 fps | 97.9% |
| SNPE Vectan Tubal 8000 | <<locked>> | 84% | 60,278 psi | 90% | 3192 fps | 100% |
| Somchem S361 | <<locked>> | 82% | 58,769 psi | 88% | 3110 fps | 99.9% |
| Somchem S385 | <<locked>> | 82% | 57,000 psi | 85% | 3100 fps | 100% |
| Vihtavuori N165 | <<locked>> | 86% | 57,246 psi | 86% | 3091 fps | 100% |
| Vihtavuori N170 | <<locked>> | 90% | 56,753 psi | 85% | 3123 fps | 97.8% |
| Vihtavuori N555 | <<locked>> | 82% | 56,811 psi | 85% | 3097 fps | 100% |
| Vihtavuori N560 | <<locked>> | 84% | 60,220 psi | 90% | 3251 fps | 100% |
| Vihtavuori N565 | <<locked>> | 88% | 57,841 psi | 87% | 3186 fps | 100% |
| Vihtavuori N568 | <<locked>> | 92% | 60,205 psi | 90% | 3268 fps | 99.9% |
| Vihtavuori N570 | <<locked>> | 92% | 57,696 psi | 86% | 3274 fps | 98.8% |
| Winchester StaBALL HD | <<locked>> | 84% | 56,347 psi | 84% | 3163 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 84% | 56,884 psi | 85% | 3100 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% | 49,443 psi | 74% | 2953 fps | 100% |
| Accurate 8700 | <<locked>> | 94% | 42,177 psi | 63% | 2894 fps | 95% |
| Accurate MAGPRO | <<locked>> | 80% | 51,924 psi | 78% | 3110 fps | 99.3% |
| ADI AR 2209 | <<locked>> | 80% | 53,447 psi | 80% | 3094 fps | 100% |
| ADI AR 2213 | <<locked>> | 80% | 48,936 psi | 73% | 3048 fps | 99.5% |
| ADI AR 2217 | <<locked>> | 80% | 36,579 psi | 55% | 2776 fps | 97.3% |
| ADI AR 2218 | 95.3 gr | 88% | 42,003 psi | 63% | 2982 fps | 95.5% |
| ADI AR 2225 | <<locked>> | 80% | 33,910 psi | 51% | 2743 fps | 99% |
| Alliant Reloder-19 | <<locked>> | 80% | 53,301 psi | 80% | 3084 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 49,690 psi | 74% | 3045 fps | 99.9% |
| Alliant Reloder-23 | <<locked>> | 80% | 48,312 psi | 72% | 2963 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 42,467 psi | 64% | 2917 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 80% | 55,912 psi | 84% | 3156 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 86% | 43,685 psi | 65% | 2976 fps | 96% |
| Alliant Reloder-50 | <<locked>> | 90% | 44,005 psi | 66% | 2972 fps | 95.5% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 46,282 psi | 69% | 2943 fps | 97.1% |
| Bofors RP15 | <<locked>> | 80% | 46,195 psi | 69% | 2979 fps | 99.7% |
| Bofors RP30 | <<locked>> | 80% | 39,755 psi | 60% | 2858 fps | 98.2% |
| Bofors RP5 | <<locked>> | 80% | 49,690 psi | 74% | 3045 fps | 99.9% |
| Hodgdon H1000 | <<locked>> | 80% | 39,900 psi | 60% | 2858 fps | 98.7% |
| Hodgdon H4831 | <<locked>> | 80% | 51,169 psi | 77% | 3038 fps | 99.4% |
| Hodgdon H4831 SC | <<locked>> | 80% | 50,314 psi | 75% | 3022 fps | 99.3% |
| Hodgdon Retumbo | 81.8 gr | 80% | 41,611 psi | 62% | 2982 fps | 99.7% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,543 psi | 43% | 1841 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 51,430 psi | 77% | 3015 fps | 99.5% |
| IMR 7828 SSC | <<locked>> | 80% | 47,645 psi | 71% | 3028 fps | 99.4% |
| IMR 7977 Enduron | <<locked>> | 88% | 53,621 psi | 80% | 3025 fps | 95.6% |
| IMR 8133 Enduron | <<locked>> | 82% | 33,808 psi | 51% | 2720 fps | 95.9% |
| Lovex S071 | <<locked>> | 80% | 42,554 psi | 64% | 2825 fps | 100% |
| Norma 217 | <<locked>> | 80% | 31,937 psi | 48% | 2684 fps | 97.4% |
| Norma MRP | <<locked>> | 80% | 53,127 psi | 80% | 3120 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 48,515 psi | 73% | 3048 fps | 99.7% |
| Ramshot Magnum | <<locked>> | 80% | 43,845 psi | 66% | 2910 fps | 99.8% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,312 psi | 44% | 1883 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 41,481 psi | 62% | 2956 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 38,203 psi | 57% | 2838 fps | 96.2% |
| Rottweil R 904 | <<locked>> | 80% | 53,766 psi | 81% | 3064 fps | 99.9% |
| Rottweil R 905 | <<locked>> | 80% | 52,997 psi | 79% | 3077 fps | 100% |
| SNPE Vectan SP 13 | <<locked>> | 94% | 44,280 psi | 66% | 2917 fps | 95.3% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 52,649 psi | 79% | 3071 fps | 100% |
| Somchem S361 | <<locked>> | 80% | 55,114 psi | 83% | 3051 fps | 99.8% |
| Somchem S385 | <<locked>> | 80% | 53,461 psi | 80% | 3045 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 46,949 psi | 70% | 2917 fps | 99.9% |
| Vihtavuori N170 | <<locked>> | 84% | 46,238 psi | 69% | 2927 fps | 95.2% |
| Vihtavuori N555 | <<locked>> | 80% | 53,243 psi | 80% | 3045 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 52,475 psi | 79% | 3123 fps | 99.6% |
| Vihtavuori N565 | <<locked>> | 80% | 44,077 psi | 66% | 2933 fps | 98.6% |
| Vihtavuori N568 | <<locked>> | 80% | 39,044 psi | 59% | 2858 fps | 96% |
| Vihtavuori N570 | 89.1 gr | 84% | 43,134 psi | 65% | 2986 fps | 95.3% |
| Winchester StaBALL HD | <<locked>> | 80% | 48,428 psi | 73% | 3041 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 49,472 psi | 74% | 2979 fps | 99.9% |
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 58 powders for 7.21 Firebird loaded with the .284 | 150gr | Swift Scirocco. Hodgdon Retumbo delivers the highest muzzle velocity at 3,310 fps; across all powders the maximum-charge window runs from 2,054 fps to 3,310 fps. Accurate 8700 gives the best case fill at 100 %, and 58 of the 58 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 1:9.5 twist; slower twists will usually not stabilise this weight. Accurate 8700, Hodgdon TrailBoss, Hodgdon US 869 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, Hodgdon Retumbo rank at the top here: for 7.21 Firebird with the .284 | 150gr | Swift Scirocco they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Hodgdon 50BMG, Ramshot LRT, Vihtavuori 20N29 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.