Load Specifications
Load data in caliber 7.21 Firebird with .284 | 152gr | Hasler ARIETE 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, Vihtavuori N570 and Alliant Reloder-33.
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% | 58,595 psi | 88% | 3081 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 51,068 psi | 77% | 3061 fps | 97.7% |
| Accurate MAGPRO | <<locked>> | 84% | 58,146 psi | 87% | 3209 fps | 99.9% |
| ADI AR 2209 | <<locked>> | 84% | 59,988 psi | 90% | 3186 fps | 100% |
| ADI AR 2213 | <<locked>> | 86% | 58,943 psi | 88% | 3205 fps | 100% |
| ADI AR 2217 | <<locked>> | 94% | 58,407 psi | 88% | 3182 fps | 100% |
| ADI AR 2218 | <<locked>> | 98% | 59,538 psi | 89% | 3330 fps | 99.6% |
| ADI AR 2225 | <<locked>> | 96% | 58,117 psi | 87% | 3205 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 84% | 59,321 psi | 89% | 3169 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 86% | 59,306 psi | 89% | 3196 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 86% | 57,261 psi | 86% | 3084 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 90% | 58,494 psi | 88% | 3173 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 82% | 58,392 psi | 88% | 3179 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 94% | 57,188 psi | 86% | 3225 fps | 99.1% |
| Alliant Reloder-50 | <<locked>> | 98% | 57,145 psi | 86% | 3215 fps | 98.8% |
| Baschieri & Pellagri 109 | <<locked>> | 88% | 58,958 psi | 88% | 3159 fps | 99.3% |
| Bofors RP15 | <<locked>> | 88% | 58,668 psi | 88% | 3182 fps | 100% |
| Bofors RP30 | <<locked>> | 92% | 58,276 psi | 87% | 3196 fps | 100% |
| Bofors RP5 | <<locked>> | 86% | 59,306 psi | 89% | 3196 fps | 100% |
| Hodgdon H1000 | <<locked>> | 92% | 60,089 psi | 90% | 3205 fps | 100% |
| Hodgdon H4831 | <<locked>> | 84% | 57,348 psi | 86% | 3130 fps | 99.9% |
| Hodgdon H4831 SC | <<locked>> | 86% | 60,321 psi | 90% | 3176 fps | 100% |
| Hodgdon Hybrid 100V | <<locked>> | 82% | 59,814 psi | 90% | 3068 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 90% | 58,189 psi | 87% | 3271 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,942 psi | 57% | 2037 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 84% | 57,392 psi | 86% | 3104 fps | 99.9% |
| IMR 7828 SSC | <<locked>> | 86% | 57,377 psi | 86% | 3186 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 92% | 59,973 psi | 90% | 3117 fps | 97% |
| IMR 8133 Enduron | <<locked>> | 98% | 56,724 psi | 85% | 3186 fps | 100% |
| Lovex S071 | <<locked>> | 90% | 56,840 psi | 85% | 3058 fps | 100% |
| Norma 217 | <<locked>> | 98% | 58,407 psi | 88% | 3209 fps | 100% |
| Norma MRP | <<locked>> | 84% | 59,611 psi | 89% | 3205 fps | 100% |
| Ramshot Grand | <<locked>> | 86% | 59,001 psi | 88% | 3209 fps | 100% |
| Ramshot Magnum | <<locked>> | 88% | 57,377 psi | 86% | 3130 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,870 psi | 58% | 2083 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 90% | 59,350 psi | 89% | 3255 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 92% | 58,305 psi | 87% | 3228 fps | 99.9% |
| Rottweil R 904 | <<locked>> | 84% | 59,944 psi | 90% | 3146 fps | 100% |
| Rottweil R 905 | <<locked>> | 84% | 59,277 psi | 89% | 3163 fps | 100% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 52,779 psi | 79% | 3068 fps | 97.6% |
| SNPE Vectan Tubal 8000 | <<locked>> | 84% | 58,900 psi | 88% | 3159 fps | 100% |
| Somchem S361 | <<locked>> | 82% | 57,638 psi | 86% | 3077 fps | 99.9% |
| Somchem S385 | <<locked>> | 84% | 59,292 psi | 89% | 3120 fps | 100% |
| Vihtavuori N165 | <<locked>> | 88% | 59,611 psi | 89% | 3110 fps | 100% |
| Vihtavuori N170 | <<locked>> | 92% | 59,234 psi | 89% | 3150 fps | 98.2% |
| Vihtavuori N555 | <<locked>> | 84% | 58,943 psi | 88% | 3117 fps | 100% |
| Vihtavuori N560 | <<locked>> | 84% | 58,871 psi | 88% | 3219 fps | 100% |
| Vihtavuori N565 | <<locked>> | 90% | 60,191 psi | 90% | 3209 fps | 100% |
| Vihtavuori N568 | <<locked>> | 92% | 58,566 psi | 88% | 3228 fps | 99.8% |
| Vihtavuori N570 | <<locked>> | 94% | 60,321 psi | 90% | 3304 fps | 99.2% |
| Winchester StaBALL HD | <<locked>> | 86% | 58,668 psi | 88% | 3182 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 86% | 59,480 psi | 89% | 3123 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% | 47,732 psi | 72% | 2910 fps | 100% |
| Accurate 8700 | <<locked>> | 96% | 43,772 psi | 66% | 2917 fps | 95.6% |
| Accurate MAGPRO | <<locked>> | 80% | 50,430 psi | 76% | 3071 fps | 99.1% |
| ADI AR 2209 | <<locked>> | 80% | 52,330 psi | 78% | 3061 fps | 100% |
| ADI AR 2213 | <<locked>> | 80% | 47,616 psi | 71% | 3009 fps | 99.4% |
| ADI AR 2217 | <<locked>> | 80% | 35,259 psi | 53% | 2730 fps | 96.8% |
| ADI AR 2218 | 96.3 gr | 90% | 43,714 psi | 66% | 3012 fps | 96.2% |
| ADI AR 2225 | <<locked>> | 80% | 32,489 psi | 49% | 2694 fps | 98.6% |
| Alliant Reloder-19 | <<locked>> | 80% | 52,011 psi | 78% | 3048 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 48,240 psi | 72% | 3005 fps | 99.9% |
| Alliant Reloder-23 | <<locked>> | 80% | 46,789 psi | 70% | 2923 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 41,147 psi | 62% | 2877 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 80% | 54,099 psi | 81% | 3114 fps | 100% |
| Alliant Reloder-33 | 93.8 gr | 86% | 42,061 psi | 63% | 2930 fps | 95.5% |
| Alliant Reloder-50 | <<locked>> | 92% | 45,382 psi | 68% | 2989 fps | 96% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 45,281 psi | 68% | 2910 fps | 96.9% |
| Bofors RP15 | <<locked>> | 80% | 44,759 psi | 67% | 2936 fps | 99.5% |
| Bofors RP30 | <<locked>> | 80% | 38,218 psi | 57% | 2808 fps | 97.8% |
| Bofors RP5 | <<locked>> | 80% | 48,240 psi | 72% | 3005 fps | 99.9% |
| Hodgdon H1000 | <<locked>> | 80% | 38,551 psi | 58% | 2812 fps | 98.5% |
| Hodgdon H4831 | <<locked>> | 80% | 49,893 psi | 75% | 3002 fps | 99.3% |
| Hodgdon H4831 SC | <<locked>> | 80% | 49,037 psi | 74% | 2986 fps | 99.2% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 56,115 psi | 84% | 3015 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 80% | 40,147 psi | 60% | 2936 fps | 99.6% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,442 psi | 43% | 1827 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 50,415 psi | 76% | 2986 fps | 99.4% |
| IMR 7828 SSC | <<locked>> | 80% | 46,253 psi | 69% | 2989 fps | 99.2% |
| IMR 7977 Enduron | <<locked>> | 88% | 52,547 psi | 79% | 2992 fps | 95.4% |
| IMR 8133 Enduron | <<locked>> | 82% | 32,256 psi | 48% | 2667 fps | 95.2% |
| Lovex S071 | <<locked>> | 80% | 40,959 psi | 61% | 2779 fps | 100% |
| Norma 217 | <<locked>> | 80% | 30,400 psi | 46% | 2628 fps | 96.7% |
| Norma MRP | <<locked>> | 80% | 51,634 psi | 77% | 3081 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 47,050 psi | 71% | 3009 fps | 99.5% |
| Ramshot Magnum | <<locked>> | 80% | 42,351 psi | 63% | 2871 fps | 99.7% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,182 psi | 44% | 1870 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 39,813 psi | 60% | 2907 fps | 99.9% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 36,477 psi | 55% | 2785 fps | 95.6% |
| Rottweil R 904 | <<locked>> | 80% | 52,692 psi | 79% | 3031 fps | 99.8% |
| Rottweil R 905 | <<locked>> | 80% | 51,735 psi | 78% | 3041 fps | 100% |
| SNPE Vectan SP 13 | <<locked>> | 96% | 45,774 psi | 69% | 2936 fps | 95.8% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 51,401 psi | 77% | 3038 fps | 100% |
| Somchem S361 | <<locked>> | 80% | 53,751 psi | 81% | 3015 fps | 99.7% |
| Somchem S385 | <<locked>> | 80% | 51,996 psi | 78% | 3009 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 45,614 psi | 68% | 2881 fps | 99.9% |
| Vihtavuori N170 | <<locked>> | 86% | 48,109 psi | 72% | 2953 fps | 95.8% |
| Vihtavuori N555 | <<locked>> | 80% | 51,532 psi | 77% | 3005 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 51,082 psi | 77% | 3084 fps | 99.5% |
| Vihtavuori N565 | <<locked>> | 80% | 42,496 psi | 64% | 2887 fps | 98.3% |
| Vihtavuori N568 | <<locked>> | 80% | 37,550 psi | 56% | 2808 fps | 95.4% |
| Vihtavuori N570 | 90.2 gr | 86% | 44,860 psi | 67% | 3012 fps | 96% |
| Winchester StaBALL HD | <<locked>> | 80% | 46,659 psi | 70% | 2999 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 48,138 psi | 72% | 2940 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 59 powders for 7.21 Firebird loaded with the .284 | 152gr | Hasler ARIETE. ADI AR 2218 delivers the highest muzzle velocity at 3,330 fps; across all powders the maximum-charge window runs from 2,037 fps to 3,330 fps. Accurate 8700 gives the best case fill at 100 %, and 59 of the 59 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 152.0 gr projectile in 0.284" calls for a 1:9.0 twist; slower twists will usually not stabilise this weight. Accurate 8700, Hodgdon TrailBoss, 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, Alliant Reloder-33 rank at the top here: for 7.21 Firebird with the .284 | 152gr | Hasler ARIETE they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Hodgdon 50BMG, Hodgdon US 869, 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.