Load Specifications
Load data in caliber 7.21 Firebird with .284 | 165gr | Norma Bondstrike bullet and 54 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 IMR 8133 Enduron.
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% | 59,756 psi | 90% | 2989 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 56,811 psi | 85% | 3058 fps | 99.2% |
| Accurate MAGPRO | <<locked>> | 82% | 59,190 psi | 89% | 3117 fps | 100% |
| ADI AR 2209 | <<locked>> | 82% | 60,292 psi | 90% | 3077 fps | 100% |
| ADI AR 2213 | <<locked>> | 84% | 59,596 psi | 89% | 3107 fps | 100% |
| ADI AR 2217 | <<locked>> | 92% | 59,611 psi | 89% | 3094 fps | 100% |
| ADI AR 2218 | <<locked>> | 94% | 56,492 psi | 85% | 3176 fps | 99.7% |
| ADI AR 2225 | <<locked>> | 94% | 59,930 psi | 90% | 3117 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 82% | 59,901 psi | 90% | 3068 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 84% | 60,118 psi | 90% | 3097 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 84% | 58,349 psi | 87% | 2989 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 88% | 59,669 psi | 89% | 3074 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 92% | 58,813 psi | 88% | 3150 fps | 99.7% |
| Alliant Reloder-50 | <<locked>> | 96% | 59,422 psi | 89% | 3150 fps | 99.5% |
| Baschieri & Pellagri 109 | <<locked>> | 86% | 59,292 psi | 89% | 3064 fps | 99.7% |
| Bofors RP15 | <<locked>> | 86% | 59,683 psi | 89% | 3091 fps | 100% |
| Bofors RP30 | <<locked>> | 90% | 59,567 psi | 89% | 3107 fps | 100% |
| Bofors RP5 | <<locked>> | 84% | 60,118 psi | 90% | 3097 fps | 100% |
| Hodgdon H1000 | <<locked>> | 88% | 56,971 psi | 85% | 3051 fps | 100% |
| Hodgdon H4831 | <<locked>> | 82% | 57,769 psi | 87% | 3031 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 82% | 56,826 psi | 85% | 3015 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 88% | 60,031 psi | 90% | 3182 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,232 psi | 57% | 1969 fps | 100% |
| Hodgdon US 869 | <<locked>> | 98% | 57,261 psi | 86% | 3058 fps | 96% |
| IMR 4955 Enduron | <<locked>> | 82% | 57,522 psi | 86% | 3005 fps | 100% |
| IMR 7828 SSC | <<locked>> | 84% | 58,407 psi | 88% | 3094 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 90% | 60,031 psi | 90% | 3025 fps | 97.8% |
| IMR 8133 Enduron | <<locked>> | 96% | 58,682 psi | 88% | 3107 fps | 100% |
| Lovex D100 | <<locked>> | 92% | 58,160 psi | 87% | 3025 fps | 96.7% |
| Lovex S071 | <<locked>> | 88% | 58,204 psi | 87% | 2966 fps | 100% |
| Norma 217 | <<locked>> | 94% | 56,507 psi | 85% | 3068 fps | 100% |
| Ramshot Grand | <<locked>> | 84% | 60,133 psi | 90% | 3117 fps | 100% |
| Ramshot LRT | <<locked>> | 96% | 60,249 psi | 90% | 3169 fps | 96.8% |
| Ramshot Magnum | <<locked>> | 86% | 58,552 psi | 88% | 3038 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,233 psi | 59% | 2011 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 86% | 56,608 psi | 85% | 3100 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 90% | 59,886 psi | 90% | 3143 fps | 100% |
| Rottweil R 904 | <<locked>> | 82% | 60,263 psi | 90% | 3045 fps | 100% |
| Rottweil R 905 | <<locked>> | 82% | 59,814 psi | 90% | 3061 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 92% | 58,160 psi | 87% | 3025 fps | 96.7% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 58,262 psi | 87% | 3064 fps | 99.1% |
| SNPE Vectan Tubal 8000 | <<locked>> | 82% | 59,451 psi | 89% | 3054 fps | 100% |
| Somchem S385 | <<locked>> | 82% | 60,104 psi | 90% | 3022 fps | 100% |
| Vihtavuori 20N29ᴾ | <<locked>> | 100% | 51,648 psi | 77% | 2972 fps | 96.7% |
| Vihtavuori 24N41 | <<locked>> | 96% | 57,856 psi | 87% | 3071 fps | 96.1% |
| Vihtavuori N165 | <<locked>> | 86% | 60,350 psi | 90% | 3012 fps | 100% |
| Vihtavuori N170 | <<locked>> | 90% | 60,104 psi | 90% | 3068 fps | 99% |
| Vihtavuori N555 | <<locked>> | 82% | 60,133 psi | 90% | 3018 fps | 100% |
| Vihtavuori N560 | <<locked>> | 82% | 59,756 psi | 90% | 3123 fps | 100% |
| Vihtavuori N565 | <<locked>> | 86% | 57,580 psi | 86% | 3061 fps | 100% |
| Vihtavuori N568 | <<locked>> | 90% | 60,060 psi | 90% | 3146 fps | 100% |
| Vihtavuori N570 | <<locked>> | 90% | 57,711 psi | 87% | 3156 fps | 99.4% |
| Winchester StaBALL HD | <<locked>> | 82% | 56,492 psi | 85% | 3035 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 84% | 59,959 psi | 90% | 3025 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% | 52,388 psi | 79% | 2881 fps | 100% |
| Accurate 8700 | <<locked>> | 90% | 39,262 psi | 59% | 2730 fps | 95% |
| Accurate MAGPRO | <<locked>> | 80% | 55,114 psi | 83% | 3051 fps | 99.9% |
| ADI AR 2209 | <<locked>> | 80% | 56,434 psi | 85% | 3022 fps | 100% |
| ADI AR 2213 | <<locked>> | 80% | 51,851 psi | 78% | 2982 fps | 100% |
| ADI AR 2217 | <<locked>> | 80% | 39,146 psi | 59% | 2733 fps | 98.9% |
| ADI AR 2218 | 90.2 gr | 84% | 38,914 psi | 58% | 2808 fps | 95.4% |
| ADI AR 2225 | <<locked>> | 80% | 36,477 psi | 55% | 2707 fps | 99.9% |
| Alliant Reloder-19 | <<locked>> | 80% | 56,188 psi | 84% | 3012 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 52,562 psi | 79% | 2979 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 80% | 51,300 psi | 77% | 2884 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 45,469 psi | 68% | 2854 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 82% | 40,524 psi | 61% | 2802 fps | 96% |
| Alliant Reloder-50 | <<locked>> | 86% | 41,075 psi | 62% | 2802 fps | 95.6% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 48,704 psi | 73% | 2884 fps | 98.4% |
| Bofors RP15 | <<locked>> | 80% | 49,037 psi | 74% | 2917 fps | 100% |
| Bofors RP30 | <<locked>> | 80% | 42,598 psi | 64% | 2812 fps | 99.4% |
| Bofors RP5 | <<locked>> | 80% | 52,562 psi | 79% | 2979 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 42,598 psi | 64% | 2805 fps | 99.7% |
| Hodgdon H4831 | <<locked>> | 80% | 54,070 psi | 81% | 2972 fps | 99.9% |
| Hodgdon H4831 SC | <<locked>> | 80% | 53,011 psi | 79% | 2956 fps | 99.9% |
| Hodgdon Retumbo | <<locked>> | 80% | 44,947 psi | 67% | 2936 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,747 psi | 43% | 1762 fps | 100% |
| Hodgdon US 869 | <<locked>> | 96% | 53,432 psi | 80% | 2995 fps | 95.1% |
| IMR 4955 Enduron | <<locked>> | 80% | 54,012 psi | 81% | 2946 fps | 100% |
| IMR 7828 SSC | <<locked>> | 80% | 50,778 psi | 76% | 2969 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 84% | 49,617 psi | 74% | 2848 fps | 95.6% |
| IMR 8133 Enduron | 78.9 gr | 80% | 33,997 psi | 51% | 2625 fps | 97.1% |
| Lovex D100 | <<locked>> | 90% | 54,099 psi | 81% | 2956 fps | 95.8% |
| Lovex S071 | <<locked>> | 80% | 45,223 psi | 68% | 2762 fps | 100% |
| Norma 217 | <<locked>> | 80% | 34,693 psi | 52% | 2651 fps | 99.1% |
| Ramshot Grand | <<locked>> | 80% | 52,040 psi | 78% | 2992 fps | 100% |
| Ramshot LRT | <<locked>> | 94% | 55,927 psi | 84% | 3097 fps | 95.9% |
| Ramshot Magnum | <<locked>> | 80% | 46,905 psi | 70% | 2854 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,573 psi | 44% | 1804 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 44,918 psi | 67% | 2907 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 41,234 psi | 62% | 2805 fps | 98.2% |
| Rottweil R 904 | <<locked>> | 80% | 56,478 psi | 85% | 2989 fps | 100% |
| Rottweil R 905 | <<locked>> | 80% | 56,014 psi | 84% | 3002 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 90% | 54,099 psi | 81% | 2956 fps | 95.8% |
| SNPE Vectan SP 13 | <<locked>> | 90% | 41,321 psi | 62% | 2753 fps | 95.4% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 55,666 psi | 83% | 2999 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 56,217 psi | 84% | 2969 fps | 100% |
| Vihtavuori 20N29 | <<locked>> | 98% | 48,051 psi | 72% | 2907 fps | 95.8% |
| Vihtavuori 24N41 | <<locked>> | 94% | 53,925 psi | 81% | 3005 fps | 95.1% |
| Vihtavuori N165 | <<locked>> | 80% | 49,676 psi | 74% | 2851 fps | 100% |
| Vihtavuori N170 | <<locked>> | 80% | 42,902 psi | 64% | 2753 fps | 95.3% |
| Vihtavuori N555 | <<locked>> | 80% | 56,347 psi | 84% | 2966 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 55,782 psi | 84% | 3061 fps | 100% |
| Vihtavuori N565 | <<locked>> | 80% | 46,876 psi | 70% | 2877 fps | 99.6% |
| Vihtavuori N568 | <<locked>> | 80% | 42,047 psi | 63% | 2822 fps | 97.9% |
| Vihtavuori N570 | 84.2 gr | 80% | 40,219 psi | 60% | 2808 fps | 95.3% |
| Winchester StaBALL HD | <<locked>> | 80% | 52,431 psi | 79% | 2979 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 52,359 psi | 78% | 2910 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 55 powders for 7.21 Firebird loaded with the .284 | 165gr | Norma Bondstrike. Hodgdon Retumbo delivers the highest muzzle velocity at 3,182 fps; across all powders the maximum-charge window runs from 1,969 fps to 3,182 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 165.0 gr projectile in 0.284" calls for a 1:9.5 twist; slower twists will usually not stabilise this weight. Accurate 8700, Hodgdon TrailBoss, 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, IMR 8133 Enduron rank at the top here: for 7.21 Firebird with the .284 | 165gr | Norma Bondstrike they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Hodgdon 50BMG 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.