Load Specifications
Load data in caliber 7.21 Firebird with .284 | 160gr | NorthFork Bonded Core 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 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% | 58,929 psi | 88% | 3015 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 55,869 psi | 84% | 3081 fps | 98.9% |
| Accurate MAGPRO | <<locked>> | 82% | 58,247 psi | 87% | 3140 fps | 100% |
| ADI AR 2209 | <<locked>> | 82% | 59,524 psi | 89% | 3104 fps | 100% |
| ADI AR 2213 | <<locked>> | 84% | 58,871 psi | 88% | 3133 fps | 100% |
| ADI AR 2217 | <<locked>> | 92% | 58,726 psi | 88% | 3120 fps | 100% |
| ADI AR 2218 | <<locked>> | 96% | 60,089 psi | 90% | 3271 fps | 99.9% |
| ADI AR 2225 | <<locked>> | 94% | 58,914 psi | 88% | 3140 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 82% | 59,146 psi | 89% | 3094 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 84% | 59,437 psi | 89% | 3123 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 84% | 57,696 psi | 86% | 3018 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 88% | 58,871 psi | 88% | 3104 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 92% | 57,899 psi | 87% | 3169 fps | 99.5% |
| Alliant Reloder-50 | <<locked>> | 96% | 58,436 psi | 88% | 3169 fps | 99.3% |
| Baschieri & Pellagri 109 | <<locked>> | 86% | 58,581 psi | 88% | 3091 fps | 99.6% |
| Bofors RP15 | <<locked>> | 86% | 58,813 psi | 88% | 3114 fps | 100% |
| Bofors RP30 | <<locked>> | 90% | 58,726 psi | 88% | 3133 fps | 100% |
| Bofors RP5 | <<locked>> | 84% | 59,437 psi | 89% | 3123 fps | 100% |
| Hodgdon H1000 | <<locked>> | 90% | 60,191 psi | 90% | 3136 fps | 100% |
| Hodgdon H4831 | <<locked>> | 82% | 56,971 psi | 85% | 3058 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 84% | 60,031 psi | 90% | 3104 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 88% | 59,030 psi | 88% | 3209 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,101 psi | 57% | 1995 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 82% | 56,826 psi | 85% | 3028 fps | 100% |
| IMR 7828 SSC | <<locked>> | 84% | 57,493 psi | 86% | 3117 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 90% | 59,393 psi | 89% | 3048 fps | 97.5% |
| IMR 8133 Enduron | <<locked>> | 96% | 57,754 psi | 87% | 3133 fps | 100% |
| Lovex D100 | <<locked>> | 92% | 57,435 psi | 86% | 3045 fps | 96.2% |
| Lovex S071 | <<locked>> | 88% | 57,392 psi | 86% | 2995 fps | 100% |
| Norma 217 | <<locked>> | 96% | 59,451 psi | 89% | 3153 fps | 100% |
| Norma MRP | <<locked>> | 82% | 59,683 psi | 89% | 3136 fps | 100% |
| Ramshot Grand | <<locked>> | 84% | 59,277 psi | 89% | 3143 fps | 100% |
| Ramshot LRT | <<locked>> | 96% | 59,350 psi | 89% | 3192 fps | 96.4% |
| Ramshot Magnum | <<locked>> | 86% | 57,696 psi | 86% | 3061 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,233 psi | 59% | 2044 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 88% | 60,089 psi | 90% | 3189 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 90% | 59,030 psi | 88% | 3166 fps | 100% |
| Rottweil R 904 | <<locked>> | 82% | 59,538 psi | 89% | 3074 fps | 100% |
| Rottweil R 905 | <<locked>> | 82% | 59,205 psi | 89% | 3091 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 92% | 57,435 psi | 86% | 3045 fps | 96.2% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 57,392 psi | 86% | 3087 fps | 98.9% |
| SNPE Vectan Tubal 8000 | <<locked>> | 82% | 58,827 psi | 88% | 3087 fps | 100% |
| Somchem S385 | <<locked>> | 82% | 59,277 psi | 89% | 3051 fps | 100% |
| Vihtavuori 20N29ᴾ | <<locked>> | 100% | 50,792 psi | 76% | 2989 fps | 96.2% |
| Vihtavuori N165 | <<locked>> | 86% | 59,654 psi | 89% | 3041 fps | 100% |
| Vihtavuori N170 | <<locked>> | 90% | 59,306 psi | 89% | 3091 fps | 98.7% |
| Vihtavuori N555 | <<locked>> | 82% | 59,292 psi | 89% | 3048 fps | 100% |
| Vihtavuori N560 | <<locked>> | 82% | 58,813 psi | 88% | 3150 fps | 100% |
| Vihtavuori N565 | <<locked>> | 86% | 56,623 psi | 85% | 3087 fps | 100% |
| Vihtavuori N568 | <<locked>> | 90% | 59,088 psi | 89% | 3169 fps | 100% |
| Vihtavuori N570 | <<locked>> | 90% | 56,724 psi | 85% | 3176 fps | 99.1% |
| Winchester StaBALL HD | <<locked>> | 84% | 59,625 psi | 89% | 3117 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 84% | 59,306 psi | 89% | 3054 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% | 51,663 psi | 77% | 2907 fps | 100% |
| Accurate 8700 | <<locked>> | 92% | 41,466 psi | 62% | 2812 fps | 95.5% |
| Accurate MAGPRO | <<locked>> | 80% | 54,389 psi | 82% | 3074 fps | 99.8% |
| ADI AR 2209 | <<locked>> | 80% | 55,695 psi | 83% | 3048 fps | 100% |
| ADI AR 2213 | <<locked>> | 80% | 51,068 psi | 77% | 3009 fps | 99.9% |
| ADI AR 2217 | <<locked>> | 80% | 38,493 psi | 58% | 2749 fps | 98.5% |
| ADI AR 2218 | 93.1 gr | 86% | 41,263 psi | 62% | 2897 fps | 96% |
| ADI AR 2225 | <<locked>> | 80% | 35,824 psi | 54% | 2723 fps | 99.7% |
| Alliant Reloder-19 | <<locked>> | 80% | 55,463 psi | 83% | 3038 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 51,793 psi | 78% | 3002 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 80% | 50,575 psi | 76% | 2913 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 44,744 psi | 67% | 2877 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 82% | 39,842 psi | 60% | 2818 fps | 95.4% |
| Alliant Reloder-50 | <<locked>> | 88% | 43,395 psi | 65% | 2887 fps | 96.1% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 48,196 psi | 72% | 2910 fps | 98.1% |
| Bofors RP15 | <<locked>> | 80% | 48,341 psi | 72% | 2943 fps | 100% |
| Bofors RP30 | <<locked>> | 80% | 41,887 psi | 63% | 2828 fps | 99.1% |
| Bofors RP5 | <<locked>> | 80% | 51,793 psi | 78% | 3002 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 42,018 psi | 63% | 2828 fps | 99.5% |
| Hodgdon H4831 | <<locked>> | 80% | 53,345 psi | 80% | 2999 fps | 99.9% |
| Hodgdon H4831 SC | <<locked>> | 80% | 52,286 psi | 78% | 2979 fps | 99.8% |
| Hodgdon Retumbo | <<locked>> | 80% | 44,092 psi | 66% | 2956 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,703 psi | 43% | 1788 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 53,374 psi | 80% | 2972 fps | 99.9% |
| IMR 7828 SSC | <<locked>> | 80% | 49,995 psi | 75% | 2992 fps | 99.9% |
| IMR 7977 Enduron | <<locked>> | 84% | 48,950 psi | 73% | 2867 fps | 95.1% |
| IMR 8133 Enduron | 79.5 gr | 80% | 33,388 psi | 50% | 2638 fps | 96.5% |
| Lovex D100 | <<locked>> | 90% | 53,461 psi | 80% | 2979 fps | 95.3% |
| Lovex S071 | <<locked>> | 80% | 44,498 psi | 67% | 2782 fps | 100% |
| Norma 217 | <<locked>> | 80% | 34,011 psi | 51% | 2667 fps | 98.7% |
| Norma MRP | <<locked>> | 80% | 55,680 psi | 83% | 3074 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 51,140 psi | 77% | 3015 fps | 100% |
| Ramshot LRT | <<locked>> | 94% | 55,143 psi | 83% | 3117 fps | 95.3% |
| Ramshot Magnum | <<locked>> | 80% | 46,224 psi | 69% | 2877 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,501 psi | 44% | 1831 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 43,990 psi | 66% | 2927 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 40,524 psi | 61% | 2822 fps | 97.7% |
| Rottweil R 904 | <<locked>> | 80% | 55,811 psi | 84% | 3015 fps | 100% |
| Rottweil R 905 | <<locked>> | 80% | 55,274 psi | 83% | 3031 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 90% | 53,461 psi | 80% | 2979 fps | 95.3% |
| SNPE Vectan SP 13 | <<locked>> | 92% | 43,555 psi | 65% | 2831 fps | 95.8% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 54,911 psi | 82% | 3025 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 55,477 psi | 83% | 2995 fps | 100% |
| Vihtavuori 20N29 | <<locked>> | 98% | 47,268 psi | 71% | 2923 fps | 95.2% |
| Vihtavuori N165 | <<locked>> | 80% | 48,994 psi | 73% | 2877 fps | 100% |
| Vihtavuori N170 | <<locked>> | 82% | 45,223 psi | 68% | 2835 fps | 95.7% |
| Vihtavuori N555 | <<locked>> | 80% | 55,593 psi | 83% | 2995 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 54,926 psi | 82% | 3084 fps | 100% |
| Vihtavuori N565 | <<locked>> | 80% | 46,253 psi | 69% | 2904 fps | 99.4% |
| Vihtavuori N568 | <<locked>> | 80% | 41,263 psi | 62% | 2835 fps | 97.4% |
| Vihtavuori N570 | 86.9 gr | 82% | 42,438 psi | 64% | 2894 fps | 95.8% |
| Winchester StaBALL HD | <<locked>> | 80% | 51,401 psi | 77% | 3002 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 51,619 psi | 77% | 2936 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 56 powders for 7.21 Firebird loaded with the .284 | 160gr | NorthFork Bonded Core. ADI AR 2218 delivers the highest muzzle velocity at 3,271 fps; across all powders the maximum-charge window runs from 1,995 fps to 3,271 fps. Accurate 8700 gives the best case fill at 100 %, and 56 of the 56 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 160.0 gr projectile in 0.284" calls for a 1:10.0 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, IMR 8133 Enduron rank at the top here: for 7.21 Firebird with the .284 | 160gr | NorthFork Bonded Core 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.