Load Specifications
Load data in caliber 7.21 Firebird with .284 | 145gr | Hasler ARIETE bullet and 53 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Hodgdon Retumbo, ADI AR 2218 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% | 57,232 psi | 86% | 3120 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 49,226 psi | 74% | 3077 fps | 96.8% |
| Accurate MAGPRO | <<locked>> | 84% | 56,608 psi | 85% | 3241 fps | 99.6% |
| ADI AR 2209 | <<locked>> | 84% | 58,479 psi | 88% | 3222 fps | 100% |
| ADI AR 2213 | <<locked>> | 86% | 57,305 psi | 86% | 3241 fps | 100% |
| ADI AR 2217 | <<locked>> | 94% | 56,666 psi | 85% | 3215 fps | 100% |
| ADI AR 2218 | <<locked>> | 98% | 57,537 psi | 86% | 3350 fps | 99.2% |
| ADI AR 2225 | <<locked>> | 96% | 56,231 psi | 84% | 3238 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 84% | 57,856 psi | 87% | 3209 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 86% | 57,682 psi | 86% | 3228 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 88% | 59,553 psi | 89% | 3179 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 90% | 56,695 psi | 85% | 3209 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 82% | 56,536 psi | 85% | 3215 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 96% | 59,727 psi | 90% | 3323 fps | 99.1% |
| Alliant Reloder-50ᴾ | <<locked>> | 100% | 59,538 psi | 89% | 3310 fps | 98.8% |
| Baschieri & Pellagri 109 | <<locked>> | 88% | 57,638 psi | 86% | 3192 fps | 98.9% |
| Bofors RP15 | <<locked>> | 88% | 57,058 psi | 86% | 3219 fps | 100% |
| Bofors RP30 | <<locked>> | 92% | 56,434 psi | 85% | 3228 fps | 100% |
| Bofors RP5 | <<locked>> | 86% | 57,682 psi | 86% | 3228 fps | 100% |
| Hodgdon H1000 | <<locked>> | 92% | 58,160 psi | 87% | 3238 fps | 100% |
| Hodgdon H4831 | <<locked>> | 86% | 59,973 psi | 90% | 3228 fps | 99.9% |
| Hodgdon H4831 SC | <<locked>> | 86% | 58,798 psi | 88% | 3212 fps | 99.9% |
| Hodgdon Hybrid 100V | <<locked>> | 82% | 58,407 psi | 88% | 3110 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 90% | 56,333 psi | 84% | 3307 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,840 psi | 57% | 2083 fps | 100% |
| IMR 4350 | <<locked>> | 82% | 60,249 psi | 90% | 3186 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 86% | 59,814 psi | 90% | 3202 fps | 99.9% |
| IMR 7828 SSC | <<locked>> | 88% | 59,959 psi | 90% | 3287 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 92% | 58,523 psi | 88% | 3146 fps | 96.3% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 58,900 psi | 88% | 3278 fps | 100% |
| Lovex S071 | <<locked>> | 92% | 59,205 psi | 89% | 3150 fps | 100% |
| Norma 217 | <<locked>> | 98% | 56,463 psi | 85% | 3241 fps | 100% |
| Norma MRP | <<locked>> | 84% | 57,870 psi | 87% | 3241 fps | 100% |
| Ramshot Grand | <<locked>> | 86% | 57,319 psi | 86% | 3245 fps | 100% |
| Ramshot Magnum | <<locked>> | 90% | 60,046 psi | 90% | 3228 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,740 psi | 58% | 2129 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 90% | 57,319 psi | 86% | 3287 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 92% | 56,376 psi | 85% | 3251 fps | 99.7% |
| Rottweil R 904 | <<locked>> | 84% | 58,566 psi | 88% | 3186 fps | 100% |
| Rottweil R 905 | <<locked>> | 84% | 57,754 psi | 87% | 3199 fps | 100% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 51,097 psi | 77% | 3091 fps | 96.8% |
| SNPE Vectan Tubal 8000 | <<locked>> | 84% | 57,392 psi | 86% | 3196 fps | 100% |
| Somchem S361 | <<locked>> | 84% | 60,292 psi | 90% | 3176 fps | 99.9% |
| Somchem S385 | <<locked>> | 84% | 58,001 psi | 87% | 3163 fps | 100% |
| Vihtavuori N165 | <<locked>> | 88% | 58,218 psi | 87% | 3150 fps | 100% |
| Vihtavuori N170 | <<locked>> | 92% | 57,725 psi | 87% | 3179 fps | 97.6% |
| Vihtavuori N555 | <<locked>> | 84% | 57,392 psi | 86% | 3156 fps | 100% |
| Vihtavuori N560 | <<locked>> | 84% | 57,217 psi | 86% | 3251 fps | 99.8% |
| Vihtavuori N565 | <<locked>> | 90% | 58,581 psi | 88% | 3245 fps | 100% |
| Vihtavuori N568 | <<locked>> | 92% | 56,797 psi | 85% | 3258 fps | 99.5% |
| Vihtavuori N570 | <<locked>> | 94% | 58,392 psi | 88% | 3330 fps | 98.7% |
| Winchester StaBALL HD | <<locked>> | 86% | 56,869 psi | 85% | 3222 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 86% | 57,943 psi | 87% | 3163 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% | 46,456 psi | 70% | 2946 fps | 100% |
| Accurate 8700 | <<locked>> | 98% | 45,585 psi | 68% | 3005 fps | 95.7% |
| Accurate MAGPRO | <<locked>> | 80% | 48,921 psi | 73% | 3097 fps | 98.6% |
| ADI AR 2209 | <<locked>> | 80% | 50,850 psi | 76% | 3094 fps | 99.9% |
| ADI AR 2213 | <<locked>> | 80% | 46,267 psi | 69% | 3038 fps | 98.9% |
| ADI AR 2217 | <<locked>> | 80% | 34,200 psi | 51% | 2749 fps | 95.8% |
| ADI AR 2218 | 96.9 gr | 90% | 42,337 psi | 63% | 3025 fps | 95% |
| ADI AR 2225 | <<locked>> | 80% | 31,444 psi | 47% | 2710 fps | 97.7% |
| Alliant Reloder-19 | <<locked>> | 80% | 50,734 psi | 76% | 3087 fps | 99.9% |
| Alliant Reloder-22 | <<locked>> | 80% | 46,905 psi | 70% | 3038 fps | 99.6% |
| Alliant Reloder-23 | <<locked>> | 80% | 45,498 psi | 68% | 2959 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 39,668 psi | 59% | 2900 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 80% | 52,547 psi | 79% | 3153 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 88% | 43,772 psi | 66% | 3022 fps | 95.6% |
| Alliant Reloder-50 | <<locked>> | 92% | 43,700 psi | 66% | 3005 fps | 95% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 44,150 psi | 66% | 2936 fps | 96.1% |
| Bofors RP15 | <<locked>> | 80% | 43,540 psi | 65% | 2969 fps | 99.1% |
| Bofors RP30 | <<locked>> | 80% | 36,985 psi | 55% | 2831 fps | 97% |
| Bofors RP5 | <<locked>> | 80% | 46,905 psi | 70% | 3038 fps | 99.6% |
| Hodgdon H1000 | <<locked>> | 80% | 37,362 psi | 56% | 2835 fps | 97.7% |
| Hodgdon H4831 | <<locked>> | 80% | 48,631 psi | 73% | 3031 fps | 98.9% |
| Hodgdon H4831 SC | <<locked>> | 80% | 47,790 psi | 72% | 3015 fps | 98.7% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 54,592 psi | 82% | 3058 fps | 100% |
| Hodgdon Retumbo | 81.3 gr | 80% | 38,769 psi | 58% | 2956 fps | 99% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,413 psi | 43% | 1867 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 56,333 psi | 84% | 3127 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 49,139 psi | 74% | 3018 fps | 99% |
| IMR 7828 SSC | <<locked>> | 80% | 44,889 psi | 67% | 3015 fps | 98.7% |
| IMR 7977 Enduron | <<locked>> | 90% | 54,781 psi | 82% | 3084 fps | 95.4% |
| IMR 8133 Enduron | <<locked>> | 84% | 33,504 psi | 50% | 2753 fps | 95.3% |
| Lovex S071 | <<locked>> | 80% | 39,842 psi | 60% | 2812 fps | 99.8% |
| Norma 217 | <<locked>> | 80% | 29,225 psi | 44% | 2644 fps | 95.6% |
| Norma MRP | <<locked>> | 80% | 50,140 psi | 75% | 3114 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 45,513 psi | 68% | 3035 fps | 99.1% |
| Ramshot Magnum | <<locked>> | 80% | 40,973 psi | 61% | 2894 fps | 99.3% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,124 psi | 44% | 1913 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 38,348 psi | 57% | 2927 fps | 99.6% |
| ReloadSwiss RS 80 | <<locked>> | 82% | 38,043 psi | 57% | 2874 fps | 95.7% |
| Rottweil R 904 | <<locked>> | 80% | 51,314 psi | 77% | 3061 fps | 99.6% |
| Rottweil R 905 | <<locked>> | 80% | 50,430 psi | 76% | 3077 fps | 99.9% |
| SNPE Vectan SP 13 | <<locked>> | 98% | 47,500 psi | 71% | 3022 fps | 95.8% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 50,082 psi | 75% | 3071 fps | 99.9% |
| Somchem S361 | <<locked>> | 80% | 52,649 psi | 79% | 3051 fps | 99.4% |
| Somchem S385 | <<locked>> | 80% | 50,705 psi | 76% | 3045 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 44,396 psi | 67% | 2913 fps | 99.6% |
| Vihtavuori N170 | <<locked>> | 88% | 50,111 psi | 75% | 3045 fps | 95.9% |
| Vihtavuori N555 | <<locked>> | 80% | 50,183 psi | 75% | 3045 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 49,617 psi | 74% | 3114 fps | 99.1% |
| Vihtavuori N565 | <<locked>> | 80% | 41,205 psi | 62% | 2913 fps | 97.6% |
| Vihtavuori N568 | <<locked>> | 82% | 39,218 psi | 59% | 2900 fps | 95.6% |
| Vihtavuori N570 | 92.8 gr | 88% | 46,630 psi | 70% | 3104 fps | 96% |
| Winchester StaBALL HD | <<locked>> | 80% | 44,933 psi | 67% | 3028 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 46,876 psi | 70% | 2972 fps | 99.6% |
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 | 145gr | Hasler ARIETE. ADI AR 2218 delivers the highest muzzle velocity at 3,350 fps; across all powders the maximum-charge window runs from 2,083 fps to 3,350 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 145.0 gr projectile in 0.284" calls for a 1:9.0 twist; slower twists will usually not stabilise this weight. Accurate 8700, Alliant Reloder-50, Hodgdon TrailBoss 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. Hodgdon Retumbo, ADI AR 2218, Vihtavuori N570 rank at the top here: for 7.21 Firebird with the .284 | 145gr | Hasler ARIETE 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.