Load Specifications
Load data in caliber 7.21 Firebird with .284 | 145gr | Barnes LRX BT bullet and 55 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% | 58,160 psi | 87% | 3133 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 50,575 psi | 76% | 3100 fps | 97.2% |
| Accurate High Country | <<locked>> | 82% | 56,623 psi | 85% | 3248 fps | 100% |
| Accurate MAGPRO | <<locked>> | 84% | 57,682 psi | 86% | 3258 fps | 99.7% |
| ADI AR 2209 | <<locked>> | 84% | 59,437 psi | 89% | 3238 fps | 100% |
| ADI AR 2213 | <<locked>> | 86% | 58,436 psi | 88% | 3258 fps | 100% |
| ADI AR 2217 | <<locked>> | 94% | 57,943 psi | 87% | 3235 fps | 100% |
| ADI AR 2218 | <<locked>> | 98% | 59,016 psi | 88% | 3373 fps | 99.4% |
| ADI AR 2225 | <<locked>> | 96% | 57,725 psi | 87% | 3258 fps | 100% |
| Alliant Power Pro Varmint | <<locked>> | 84% | 58,653 psi | 88% | 3219 fps | 100% |
| Alliant Power Pro Varmint | <<locked>> | 84% | 59,596 psi | 89% | 3232 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 84% | 58,958 psi | 88% | 3222 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 86% | 58,784 psi | 88% | 3245 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 86% | 56,869 psi | 85% | 3140 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 90% | 57,827 psi | 87% | 3222 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 82% | 57,783 psi | 87% | 3228 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 94% | 56,782 psi | 85% | 3271 fps | 98.8% |
| Alliant Reloder-50 | <<locked>> | 98% | 56,724 psi | 85% | 3258 fps | 98.4% |
| Baschieri & Pellagri 109 | <<locked>> | 88% | 58,639 psi | 88% | 3212 fps | 99.1% |
| Bofors RP15 | <<locked>> | 88% | 58,146 psi | 87% | 3235 fps | 100% |
| Bofors RP30 | <<locked>> | 92% | 57,711 psi | 87% | 3245 fps | 100% |
| Bofors RP5 | <<locked>> | 86% | 58,784 psi | 88% | 3245 fps | 100% |
| Hodgdon H1000 | <<locked>> | 92% | 59,451 psi | 89% | 3255 fps | 100% |
| Hodgdon H4831 | <<locked>> | 84% | 56,927 psi | 85% | 3182 fps | 99.8% |
| Hodgdon H4831 SC | <<locked>> | 86% | 59,843 psi | 90% | 3228 fps | 99.9% |
| Hodgdon Hybrid 100V | <<locked>> | 82% | 59,451 psi | 89% | 3127 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 90% | 57,798 psi | 87% | 3323 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,768 psi | 57% | 2087 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 84% | 56,927 psi | 85% | 3156 fps | 99.8% |
| IMR 7828 SSC | <<locked>> | 86% | 56,884 psi | 85% | 3238 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 92% | 59,524 psi | 89% | 3166 fps | 96.6% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 60,350 psi | 90% | 3301 fps | 100% |
| Lovex S071 | <<locked>> | 92% | 60,307 psi | 90% | 3166 fps | 100% |
| Norma 217 | <<locked>> | 98% | 57,769 psi | 87% | 3255 fps | 100% |
| Norma MRP | <<locked>> | 84% | 59,016 psi | 88% | 3261 fps | 100% |
| Ramshot Grand | <<locked>> | 86% | 58,523 psi | 88% | 3261 fps | 100% |
| Ramshot Magnum | <<locked>> | 88% | 56,942 psi | 85% | 3179 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,812 psi | 58% | 2136 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 90% | 58,871 psi | 88% | 3307 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 92% | 57,798 psi | 87% | 3271 fps | 99.8% |
| Rottweil R 904 | <<locked>> | 84% | 59,625 psi | 89% | 3202 fps | 100% |
| Rottweil R 905 | <<locked>> | 84% | 58,726 psi | 88% | 3215 fps | 100% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 52,417 psi | 79% | 3114 fps | 97.2% |
| SNPE Vectan Tubal 8000 | <<locked>> | 84% | 58,349 psi | 87% | 3212 fps | 100% |
| Somchem S361 | <<locked>> | 82% | 57,174 psi | 86% | 3130 fps | 99.8% |
| Somchem S385 | <<locked>> | 84% | 58,900 psi | 88% | 3176 fps | 100% |
| Vihtavuori N165 | <<locked>> | 88% | 59,263 psi | 89% | 3166 fps | 100% |
| Vihtavuori N170 | <<locked>> | 92% | 58,740 psi | 88% | 3199 fps | 97.9% |
| Vihtavuori N555 | <<locked>> | 84% | 58,436 psi | 88% | 3169 fps | 100% |
| Vihtavuori N560 | <<locked>> | 84% | 58,320 psi | 87% | 3268 fps | 99.9% |
| Vihtavuori N565 | <<locked>> | 90% | 59,814 psi | 90% | 3264 fps | 100% |
| Vihtavuori N568 | <<locked>> | 92% | 57,972 psi | 87% | 3274 fps | 99.7% |
| Vihtavuori N570 | <<locked>> | 94% | 59,843 psi | 90% | 3353 fps | 98.9% |
| Winchester StaBALL HD | <<locked>> | 86% | 58,189 psi | 87% | 3235 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 86% | 59,146 psi | 89% | 3179 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% | 47,369 psi | 71% | 2959 fps | 100% |
| Accurate 8700 | <<locked>> | 96% | 43,323 psi | 65% | 2953 fps | 95% |
| Accurate High Country | <<locked>> | 80% | 52,605 psi | 79% | 3179 fps | 99.8% |
| Accurate MAGPRO | <<locked>> | 80% | 50,009 psi | 75% | 3120 fps | 98.8% |
| ADI AR 2209 | <<locked>> | 80% | 51,822 psi | 78% | 3110 fps | 99.9% |
| ADI AR 2213 | <<locked>> | 80% | 47,181 psi | 71% | 3058 fps | 99.1% |
| ADI AR 2217 | <<locked>> | 80% | 34,969 psi | 52% | 2769 fps | 96.3% |
| ADI AR 2218 | 98.6 gr | 90% | 43,410 psi | 65% | 3054 fps | 95.6% |
| ADI AR 2225 | <<locked>> | 80% | 32,184 psi | 48% | 2730 fps | 98.1% |
| Alliant Power Pro Varmint | <<locked>> | 80% | 51,198 psi | 77% | 3094 fps | 99.9% |
| Alliant Power Pro Varmint | <<locked>> | 80% | 52,156 psi | 78% | 3107 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 80% | 51,619 psi | 77% | 3100 fps | 99.9% |
| Alliant Reloder-22 | <<locked>> | 80% | 47,834 psi | 72% | 3058 fps | 99.8% |
| Alliant Reloder-23 | <<locked>> | 80% | 46,470 psi | 70% | 2976 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 40,611 psi | 61% | 2917 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 80% | 53,577 psi | 80% | 3166 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 88% | 45,005 psi | 67% | 3041 fps | 96.1% |
| Alliant Reloder-50 | <<locked>> | 92% | 44,947 psi | 67% | 3028 fps | 95.4% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 44,846 psi | 67% | 2953 fps | 96.4% |
| Bofors RP15 | <<locked>> | 80% | 44,425 psi | 67% | 2982 fps | 99.3% |
| Bofors RP30 | <<locked>> | 80% | 37,840 psi | 57% | 2848 fps | 97.3% |
| Bofors RP5 | <<locked>> | 80% | 47,834 psi | 72% | 3058 fps | 99.8% |
| Hodgdon H1000 | <<locked>> | 80% | 38,189 psi | 57% | 2854 fps | 98% |
| Hodgdon H4831 | <<locked>> | 80% | 49,487 psi | 74% | 3048 fps | 99.1% |
| Hodgdon H4831 SC | <<locked>> | 80% | 48,660 psi | 73% | 3035 fps | 98.9% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 55,651 psi | 83% | 3074 fps | 100% |
| Hodgdon Retumbo | 82.7 gr | 80% | 39,711 psi | 60% | 2979 fps | 99.3% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,369 psi | 43% | 1873 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 49,951 psi | 75% | 3035 fps | 99.2% |
| IMR 7828 SSC | <<locked>> | 80% | 45,847 psi | 69% | 3035 fps | 98.9% |
| IMR 7977 Enduron | <<locked>> | 90% | 55,622 psi | 83% | 3100 fps | 95.8% |
| IMR 8133 Enduron | <<locked>> | 84% | 34,316 psi | 51% | 2769 fps | 95.7% |
| Lovex S071 | <<locked>> | 80% | 40,625 psi | 61% | 2825 fps | 99.9% |
| Norma 217 | <<locked>> | 80% | 29,965 psi | 45% | 2657 fps | 96% |
| Norma MRP | <<locked>> | 80% | 51,082 psi | 77% | 3130 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 46,499 psi | 70% | 3051 fps | 99.3% |
| Ramshot Magnum | <<locked>> | 80% | 41,829 psi | 63% | 2910 fps | 99.5% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,211 psi | 44% | 1919 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 39,349 psi | 59% | 2946 fps | 99.8% |
| ReloadSwiss RS 80 | <<locked>> | 82% | 39,131 psi | 59% | 2900 fps | 96.2% |
| Rottweil R 904 | <<locked>> | 80% | 52,199 psi | 78% | 3081 fps | 99.7% |
| Rottweil R 905 | <<locked>> | 80% | 51,227 psi | 77% | 3091 fps | 100% |
| SNPE Vectan SP 13 | <<locked>> | 96% | 45,411 psi | 68% | 2976 fps | 95.3% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 50,879 psi | 76% | 3084 fps | 99.9% |
| Somchem S361 | <<locked>> | 80% | 53,388 psi | 80% | 3068 fps | 99.5% |
| Somchem S385 | <<locked>> | 80% | 51,605 psi | 77% | 3058 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 45,252 psi | 68% | 2930 fps | 99.7% |
| Vihtavuori N170 | <<locked>> | 86% | 47,732 psi | 72% | 2995 fps | 95.3% |
| Vihtavuori N555 | <<locked>> | 80% | 51,184 psi | 77% | 3058 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 50,546 psi | 76% | 3130 fps | 99.3% |
| Vihtavuori N565 | <<locked>> | 80% | 42,061 psi | 63% | 2930 fps | 97.8% |
| Vihtavuori N568 | <<locked>> | 82% | 40,030 psi | 60% | 2920 fps | 96% |
| Vihtavuori N570 | 92.3 gr | 86% | 44,425 psi | 67% | 3051 fps | 95.3% |
| Winchester StaBALL HD | <<locked>> | 80% | 46,108 psi | 69% | 3048 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 47,718 psi | 72% | 2986 fps | 99.7% |
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 55 powders for 7.21 Firebird loaded with the .284 | 145gr | Barnes LRX BT. ADI AR 2218 delivers the highest muzzle velocity at 3,373 fps; across all powders the maximum-charge window runs from 2,087 fps to 3,373 fps. Accurate 8700 gives the best case fill at 100 %, and 55 of the 55 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 1:9.5 twist; slower twists will usually not stabilise this weight. Accurate 8700, Hodgdon TrailBoss, IMR 8133 Enduron 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 | Barnes LRX 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.