Load Specifications
Load data in caliber 7.21 Firebird with .284 | 150gr | Prvi Partizan HP BT 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>> | 84% | 57,638 psi | 86% | 3077 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 54,128 psi | 81% | 3120 fps | 98.3% |
| Accurate MAGPRO | <<locked>> | 82% | 56,956 psi | 85% | 3199 fps | 99.8% |
| ADI AR 2209 | <<locked>> | 82% | 58,175 psi | 87% | 3169 fps | 100% |
| ADI AR 2213 | <<locked>> | 84% | 57,290 psi | 86% | 3192 fps | 100% |
| ADI AR 2217 | <<locked>> | 92% | 57,174 psi | 86% | 3176 fps | 100% |
| ADI AR 2218 | <<locked>> | 96% | 58,305 psi | 87% | 3320 fps | 99.5% |
| ADI AR 2225 | <<locked>> | 94% | 57,305 psi | 86% | 3199 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 82% | 57,827 psi | 87% | 3159 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 84% | 57,856 psi | 87% | 3186 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 86% | 59,988 psi | 90% | 3136 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 88% | 57,261 psi | 86% | 3163 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 92% | 56,130 psi | 84% | 3215 fps | 98.9% |
| Alliant Reloder-50 | <<locked>> | 96% | 56,623 psi | 85% | 3212 fps | 98.7% |
| Baschieri & Pellagri 109 | <<locked>> | 86% | 57,392 psi | 86% | 3146 fps | 99.2% |
| Bofors RP15 | <<locked>> | 86% | 57,435 psi | 86% | 3179 fps | 100% |
| Bofors RP30 | <<locked>> | 90% | 57,246 psi | 86% | 3192 fps | 100% |
| Bofors RP5 | <<locked>> | 84% | 57,856 psi | 87% | 3186 fps | 100% |
| Hodgdon H1000 | <<locked>> | 90% | 58,581 psi | 88% | 3196 fps | 100% |
| Hodgdon H4831 | <<locked>> | 84% | 59,712 psi | 90% | 3179 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 84% | 58,566 psi | 88% | 3163 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 88% | 57,188 psi | 86% | 3264 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,072 psi | 57% | 2060 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 84% | 59,408 psi | 89% | 3150 fps | 100% |
| IMR 7828 SSC | <<locked>> | 86% | 59,973 psi | 90% | 3238 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 90% | 58,262 psi | 87% | 3107 fps | 96.8% |
| IMR 8133 Enduron | <<locked>> | 98% | 60,089 psi | 90% | 3245 fps | 100% |
| Lovex D100 | <<locked>> | 94% | 60,104 psi | 90% | 3159 fps | 96.2% |
| Lovex S071 | <<locked>> | 90% | 59,712 psi | 90% | 3110 fps | 100% |
| Norma 217 | <<locked>> | 96% | 57,769 psi | 87% | 3209 fps | 100% |
| Norma MRP | <<locked>> | 82% | 58,218 psi | 87% | 3199 fps | 100% |
| Ramshot Grand | <<locked>> | 84% | 57,609 psi | 86% | 3202 fps | 100% |
| Ramshot Magnum | <<locked>> | 86% | 56,188 psi | 84% | 3120 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,160 psi | 59% | 2110 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 88% | 58,131 psi | 87% | 3245 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 90% | 57,290 psi | 86% | 3219 fps | 99.9% |
| Rottweil R 904 | <<locked>> | 82% | 58,305 psi | 87% | 3136 fps | 100% |
| Rottweil R 905 | <<locked>> | 82% | 57,841 psi | 87% | 3153 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 94% | 60,104 psi | 90% | 3159 fps | 96.2% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 55,840 psi | 84% | 3133 fps | 98.2% |
| SNPE Vectan Tubal 8000 | <<locked>> | 82% | 57,479 psi | 86% | 3150 fps | 100% |
| Somchem S361 | <<locked>> | 82% | 59,756 psi | 90% | 3123 fps | 100% |
| Somchem S385 | <<locked>> | 82% | 57,943 psi | 87% | 3114 fps | 100% |
| Vihtavuori N165 | <<locked>> | 86% | 58,160 psi | 87% | 3100 fps | 100% |
| Vihtavuori N170 | <<locked>> | 90% | 57,856 psi | 87% | 3140 fps | 98% |
| Vihtavuori N555 | <<locked>> | 82% | 57,740 psi | 87% | 3114 fps | 100% |
| Vihtavuori N560 | <<locked>> | 82% | 57,421 psi | 86% | 3205 fps | 99.9% |
| Vihtavuori N565 | <<locked>> | 88% | 59,103 psi | 89% | 3205 fps | 100% |
| Vihtavuori N568 | <<locked>> | 90% | 57,377 psi | 86% | 3219 fps | 99.7% |
| Vihtavuori N570 | <<locked>> | 92% | 59,219 psi | 89% | 3297 fps | 99.1% |
| Winchester StaBALL HD | <<locked>> | 84% | 57,798 psi | 87% | 3179 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 84% | 58,001 psi | 87% | 3114 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% | 50,285 psi | 75% | 2966 fps | 100% |
| Accurate 8700 | <<locked>> | 94% | 43,352 psi | 65% | 2917 fps | 95.5% |
| Accurate MAGPRO | <<locked>> | 80% | 53,040 psi | 80% | 3130 fps | 99.5% |
| ADI AR 2209 | <<locked>> | 80% | 54,505 psi | 82% | 3110 fps | 100% |
| ADI AR 2213 | <<locked>> | 80% | 49,792 psi | 75% | 3061 fps | 99.6% |
| ADI AR 2217 | <<locked>> | 80% | 37,289 psi | 56% | 2789 fps | 97.6% |
| ADI AR 2218 | 97.1 gr | 88% | 43,120 psi | 65% | 3009 fps | 96% |
| ADI AR 2225 | <<locked>> | 80% | 34,737 psi | 52% | 2762 fps | 99.2% |
| Alliant Reloder-19 | <<locked>> | 80% | 54,114 psi | 81% | 3097 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 50,531 psi | 76% | 3061 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 80% | 49,211 psi | 74% | 2972 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 43,511 psi | 65% | 2933 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 84% | 41,452 psi | 62% | 2920 fps | 95.2% |
| Alliant Reloder-50 | <<locked>> | 90% | 45,295 psi | 68% | 2995 fps | 96% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 47,036 psi | 71% | 2959 fps | 97.4% |
| Bofors RP15 | <<locked>> | 80% | 47,021 psi | 70% | 2992 fps | 99.8% |
| Bofors RP30 | <<locked>> | 80% | 40,567 psi | 61% | 2871 fps | 98.4% |
| Bofors RP5 | <<locked>> | 80% | 50,531 psi | 76% | 3061 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 40,669 psi | 61% | 2871 fps | 98.9% |
| Hodgdon H4831 | <<locked>> | 80% | 52,112 psi | 78% | 3054 fps | 99.6% |
| Hodgdon H4831 SC | <<locked>> | 80% | 51,097 psi | 77% | 3038 fps | 99.5% |
| Hodgdon Retumbo | 83.3 gr | 80% | 42,699 psi | 64% | 3002 fps | 99.9% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,587 psi | 43% | 1847 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 52,315 psi | 78% | 3031 fps | 99.6% |
| IMR 7828 SSC | <<locked>> | 80% | 48,660 psi | 73% | 3045 fps | 99.5% |
| IMR 7977 Enduron | <<locked>> | 86% | 51,169 psi | 77% | 2982 fps | 95.1% |
| IMR 8133 Enduron | <<locked>> | 80% | 32,242 psi | 48% | 2674 fps | 95.2% |
| Lovex D100 | <<locked>> | 92% | 55,999 psi | 84% | 3091 fps | 95.3% |
| Lovex S071 | <<locked>> | 80% | 43,366 psi | 65% | 2838 fps | 100% |
| Norma 217 | <<locked>> | 80% | 32,880 psi | 49% | 2703 fps | 97.8% |
| Norma MRP | <<locked>> | 80% | 54,201 psi | 81% | 3136 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 49,632 psi | 74% | 3068 fps | 99.8% |
| Ramshot Magnum | <<locked>> | 80% | 44,817 psi | 67% | 2927 fps | 99.9% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,486 psi | 44% | 1893 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 42,496 psi | 64% | 2972 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 39,233 psi | 59% | 2861 fps | 96.7% |
| Rottweil R 904 | <<locked>> | 80% | 54,708 psi | 82% | 3077 fps | 99.9% |
| Rottweil R 905 | <<locked>> | 80% | 54,027 psi | 81% | 3091 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 92% | 55,999 psi | 84% | 3091 fps | 95.3% |
| SNPE Vectan SP 13 | <<locked>> | 94% | 45,310 psi | 68% | 2933 fps | 95.7% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 53,679 psi | 80% | 3087 fps | 100% |
| Somchem S361 | <<locked>> | 80% | 55,927 psi | 84% | 3064 fps | 99.8% |
| Somchem S385 | <<locked>> | 80% | 54,259 psi | 81% | 3058 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 47,703 psi | 72% | 2930 fps | 100% |
| Vihtavuori N170 | <<locked>> | 84% | 47,311 psi | 71% | 2946 fps | 95.7% |
| Vihtavuori N555 | <<locked>> | 80% | 54,157 psi | 81% | 3058 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 53,490 psi | 80% | 3140 fps | 99.7% |
| Vihtavuori N565 | <<locked>> | 80% | 45,020 psi | 67% | 2949 fps | 98.8% |
| Vihtavuori N568 | <<locked>> | 80% | 40,074 psi | 60% | 2877 fps | 96.4% |
| Vihtavuori N570 | 90.8 gr | 84% | 44,338 psi | 66% | 3009 fps | 95.8% |
| Winchester StaBALL HD | <<locked>> | 80% | 49,705 psi | 75% | 3058 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 50,386 psi | 76% | 2992 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 52 powders for 7.21 Firebird loaded with the .284 | 150gr | Prvi Partizan HP BT. ADI AR 2218 delivers the highest muzzle velocity at 3,320 fps; across all powders the maximum-charge window runs from 2,060 fps to 3,320 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 1:11.5 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 | Prvi Partizan HP BT 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.