Load Specifications
Load data in caliber 7.21 Firebird with .284 | 155gr | Federal Terminal Ascent Component 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 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% | 56,724 psi | 85% | 3025 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 52,866 psi | 79% | 3071 fps | 98.2% |
| Accurate MAGPRO | <<locked>> | 84% | 60,031 psi | 90% | 3209 fps | 100% |
| ADI AR 2209 | <<locked>> | 82% | 57,334 psi | 86% | 3114 fps | 100% |
| ADI AR 2213 | <<locked>> | 84% | 56,420 psi | 85% | 3140 fps | 100% |
| ADI AR 2217 | <<locked>> | 94% | 60,278 psi | 90% | 3186 fps | 100% |
| ADI AR 2218 | <<locked>> | 96% | 56,869 psi | 85% | 3261 fps | 99.5% |
| ADI AR 2225 | <<locked>> | 96% | 60,075 psi | 90% | 3205 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 82% | 57,058 psi | 86% | 3107 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 84% | 57,000 psi | 85% | 3130 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 86% | 59,030 psi | 88% | 3081 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 90% | 60,205 psi | 90% | 3166 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 82% | 60,292 psi | 90% | 3176 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 94% | 59,088 psi | 89% | 3232 fps | 99.4% |
| Alliant Reloder-50 | <<locked>> | 98% | 59,393 psi | 89% | 3228 fps | 99.2% |
| Baschieri & Pellagri 109 | <<locked>> | 86% | 56,623 psi | 85% | 3097 fps | 99.2% |
| Bofors RP15 | <<locked>> | 88% | 60,234 psi | 90% | 3179 fps | 100% |
| Bofors RP30 | <<locked>> | 92% | 60,118 psi | 90% | 3199 fps | 100% |
| Bofors RP5 | <<locked>> | 84% | 57,000 psi | 85% | 3130 fps | 100% |
| Hodgdon H1000 | <<locked>> | 90% | 57,537 psi | 86% | 3143 fps | 100% |
| Hodgdon H4831 | <<locked>> | 84% | 58,697 psi | 88% | 3123 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 84% | 57,754 psi | 87% | 3107 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 90% | 60,249 psi | 90% | 3274 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,101 psi | 57% | 2021 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 84% | 58,581 psi | 88% | 3097 fps | 100% |
| IMR 7828 SSC | <<locked>> | 86% | 59,103 psi | 89% | 3186 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 90% | 57,377 psi | 86% | 3051 fps | 96.7% |
| IMR 8133 Enduron | <<locked>> | 98% | 58,682 psi | 88% | 3189 fps | 100% |
| Lovex D100 | <<locked>> | 94% | 59,016 psi | 88% | 3104 fps | 96.1% |
| Lovex S071 | <<locked>> | 90% | 58,871 psi | 88% | 3054 fps | 100% |
| Norma 217 | <<locked>> | 96% | 56,478 psi | 85% | 3153 fps | 100% |
| Norma MRP | <<locked>> | 82% | 57,319 psi | 86% | 3146 fps | 100% |
| Ramshot Grand | <<locked>> | 84% | 56,536 psi | 85% | 3146 fps | 100% |
| Ramshot Magnum | <<locked>> | 88% | 59,408 psi | 89% | 3130 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,073 psi | 59% | 2067 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 88% | 56,971 psi | 85% | 3192 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 90% | 56,028 psi | 84% | 3166 fps | 99.9% |
| Rottweil R 904 | <<locked>> | 82% | 57,493 psi | 86% | 3084 fps | 100% |
| Rottweil R 905 | <<locked>> | 82% | 56,985 psi | 85% | 3100 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 94% | 59,016 psi | 88% | 3104 fps | 96.1% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 54,549 psi | 82% | 3077 fps | 98.1% |
| SNPE Vectan Tubal 8000 | <<locked>> | 84% | 60,350 psi | 90% | 3150 fps | 100% |
| Somchem S361 | <<locked>> | 82% | 58,958 psi | 88% | 3071 fps | 100% |
| Somchem S385 | <<locked>> | 82% | 57,203 psi | 86% | 3064 fps | 100% |
| Vihtavuori N165 | <<locked>> | 86% | 57,435 psi | 86% | 3051 fps | 100% |
| Vihtavuori N170 | <<locked>> | 90% | 56,956 psi | 85% | 3091 fps | 98% |
| Vihtavuori N555 | <<locked>> | 82% | 57,000 psi | 85% | 3061 fps | 100% |
| Vihtavuori N560 | <<locked>> | 82% | 56,579 psi | 85% | 3156 fps | 100% |
| Vihtavuori N565 | <<locked>> | 88% | 58,131 psi | 87% | 3150 fps | 100% |
| Vihtavuori N568 | <<locked>> | 90% | 56,362 psi | 84% | 3166 fps | 99.7% |
| Vihtavuori N570 | <<locked>> | 92% | 57,986 psi | 87% | 3241 fps | 99% |
| Winchester StaBALL HD | <<locked>> | 84% | 56,550 psi | 85% | 3123 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 84% | 57,029 psi | 85% | 3061 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% | 49,603 psi | 74% | 2917 fps | 100% |
| Accurate 8700 | <<locked>> | 94% | 42,337 psi | 63% | 2864 fps | 95.3% |
| Accurate MAGPRO | <<locked>> | 80% | 52,025 psi | 78% | 3077 fps | 99.4% |
| ADI AR 2209 | <<locked>> | 80% | 53,766 psi | 81% | 3058 fps | 100% |
| ADI AR 2213 | <<locked>> | 80% | 49,110 psi | 74% | 3012 fps | 99.6% |
| ADI AR 2217 | <<locked>> | 80% | 36,680 psi | 55% | 2743 fps | 97.6% |
| ADI AR 2218 | 93.6 gr | 88% | 42,163 psi | 63% | 2953 fps | 95.9% |
| ADI AR 2225 | <<locked>> | 80% | 34,040 psi | 51% | 2717 fps | 99.2% |
| Alliant Reloder-19 | <<locked>> | 80% | 53,417 psi | 80% | 3048 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 49,850 psi | 75% | 3012 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 80% | 48,573 psi | 73% | 2923 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 42,757 psi | 64% | 2884 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 80% | 56,130 psi | 84% | 3117 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 84% | 40,611 psi | 61% | 2874 fps | 95.2% |
| Alliant Reloder-50 | <<locked>> | 90% | 44,135 psi | 66% | 2943 fps | 95.9% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 46,369 psi | 70% | 2910 fps | 97.3% |
| Bofors RP15 | <<locked>> | 80% | 46,311 psi | 69% | 2943 fps | 99.8% |
| Bofors RP30 | <<locked>> | 80% | 39,885 psi | 60% | 2825 fps | 98.4% |
| Bofors RP5 | <<locked>> | 80% | 49,850 psi | 75% | 3012 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 40,089 psi | 60% | 2825 fps | 99% |
| Hodgdon H4831 | <<locked>> | 80% | 51,343 psi | 77% | 3002 fps | 99.6% |
| Hodgdon H4831 SC | <<locked>> | 80% | 50,473 psi | 76% | 2986 fps | 99.5% |
| Hodgdon Retumbo | 80.3 gr | 80% | 41,800 psi | 63% | 2949 fps | 99.8% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,558 psi | 43% | 1808 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 51,692 psi | 77% | 2982 fps | 99.6% |
| IMR 7828 SSC | <<locked>> | 80% | 47,819 psi | 72% | 2992 fps | 99.5% |
| IMR 7977 Enduron | <<locked>> | 86% | 50,531 psi | 76% | 2930 fps | 95.1% |
| IMR 8133 Enduron | <<locked>> | 80% | 31,705 psi | 48% | 2628 fps | 95.3% |
| Lovex D100 | <<locked>> | 92% | 54,998 psi | 82% | 3038 fps | 95.2% |
| Lovex S071 | <<locked>> | 80% | 42,844 psi | 64% | 2792 fps | 100% |
| Norma 217 | <<locked>> | 80% | 32,184 psi | 48% | 2661 fps | 97.8% |
| Norma MRP | <<locked>> | 80% | 53,403 psi | 80% | 3084 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 48,791 psi | 73% | 3015 fps | 99.8% |
| Ramshot Magnum | <<locked>> | 80% | 43,976 psi | 66% | 2877 fps | 99.9% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,341 psi | 44% | 1850 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 41,684 psi | 62% | 2923 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 38,363 psi | 57% | 2812 fps | 96.6% |
| Rottweil R 904 | <<locked>> | 80% | 54,012 psi | 81% | 3025 fps | 99.9% |
| Rottweil R 905 | <<locked>> | 80% | 53,316 psi | 80% | 3038 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 92% | 54,998 psi | 82% | 3038 fps | 95.2% |
| SNPE Vectan SP 13 | <<locked>> | 94% | 44,367 psi | 67% | 2884 fps | 95.6% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 52,953 psi | 79% | 3035 fps | 100% |
| Somchem S361 | <<locked>> | 80% | 55,201 psi | 83% | 3015 fps | 99.8% |
| Somchem S385 | <<locked>> | 80% | 53,621 psi | 80% | 3009 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 47,108 psi | 71% | 2884 fps | 100% |
| Vihtavuori N170 | <<locked>> | 84% | 46,412 psi | 70% | 2894 fps | 95.6% |
| Vihtavuori N555 | <<locked>> | 80% | 53,359 psi | 80% | 3005 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 52,736 psi | 79% | 3091 fps | 99.7% |
| Vihtavuori N565 | <<locked>> | 80% | 44,251 psi | 66% | 2900 fps | 98.8% |
| Vihtavuori N568 | <<locked>> | 80% | 39,291 psi | 59% | 2828 fps | 96.4% |
| Vihtavuori N570 | 87.5 gr | 84% | 43,308 psi | 65% | 2956 fps | 95.7% |
| Winchester StaBALL HD | <<locked>> | 80% | 48,704 psi | 73% | 3005 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 49,661 psi | 74% | 2943 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 | 155gr | Federal Terminal Ascent Component. Hodgdon Retumbo delivers the highest muzzle velocity at 3,274 fps; across all powders the maximum-charge window runs from 2,021 fps to 3,274 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 155.0 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, Vihtavuori N570, Hodgdon Retumbo rank at the top here: for 7.21 Firebird with the .284 | 155gr | Federal Terminal Ascent Component 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.