Load Specifications
Load data in caliber 7.21 Firebird with .284 | 160gr | Barnes XLC S bullet and 44 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>> | 82% | 59,350 psi | 89% | 3009 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 60,017 psi | 90% | 3136 fps | 99.4% |
| ADI AR 2213 | <<locked>> | 82% | 58,044 psi | 87% | 3114 fps | 100% |
| ADI AR 2217 | <<locked>> | 90% | 58,262 psi | 87% | 3104 fps | 100% |
| ADI AR 2218 | <<locked>> | 94% | 59,466 psi | 89% | 3255 fps | 99.8% |
| ADI AR 2225 | <<locked>> | 92% | 58,769 psi | 88% | 3130 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 82% | 59,016 psi | 88% | 3110 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 82% | 57,624 psi | 86% | 3005 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 86% | 58,755 psi | 88% | 3091 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 90% | 57,841 psi | 87% | 3163 fps | 99.5% |
| Alliant Reloder-50 | <<locked>> | 94% | 59,263 psi | 89% | 3176 fps | 99.4% |
| Baschieri & Pellagri 109 | <<locked>> | 84% | 57,406 psi | 86% | 3064 fps | 99.5% |
| Bofors RP15 | <<locked>> | 84% | 58,624 psi | 88% | 3104 fps | 100% |
| Bofors RP30 | <<locked>> | 88% | 58,987 psi | 88% | 3130 fps | 100% |
| Bofors RP5 | <<locked>> | 82% | 59,016 psi | 88% | 3110 fps | 100% |
| Hodgdon H1000 | <<locked>> | 88% | 59,466 psi | 89% | 3117 fps | 100% |
| Hodgdon H4831 | <<locked>> | 82% | 60,046 psi | 90% | 3094 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 82% | 59,117 psi | 89% | 3081 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 86% | 58,769 psi | 88% | 3196 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,406 psi | 58% | 1998 fps | 100% |
| Hodgdon US 869 | <<locked>> | 98% | 60,321 psi | 90% | 3133 fps | 96.4% |
| IMR 4955 Enduron | <<locked>> | 82% | 59,538 psi | 89% | 3061 fps | 100% |
| IMR 7828 SSC | <<locked>> | 82% | 56,898 psi | 85% | 3097 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 88% | 58,436 psi | 88% | 3025 fps | 97.3% |
| IMR 8133 Enduron | <<locked>> | 94% | 58,160 psi | 87% | 3130 fps | 100% |
| Lovex D100 | <<locked>> | 90% | 56,840 psi | 85% | 3025 fps | 96.1% |
| Lovex S071 | <<locked>> | 86% | 58,146 psi | 87% | 2989 fps | 100% |
| Norma 217 | <<locked>> | 94% | 60,104 psi | 90% | 3150 fps | 100% |
| Ramshot Grand | <<locked>> | 82% | 58,813 psi | 88% | 3127 fps | 100% |
| Ramshot LRT | <<locked>> | 94% | 58,813 psi | 88% | 3173 fps | 96.3% |
| Ramshot Magnum | <<locked>> | 84% | 57,450 psi | 86% | 3051 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,610 psi | 59% | 2047 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 86% | 59,857 psi | 90% | 3176 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 88% | 59,030 psi | 88% | 3159 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 90% | 56,840 psi | 85% | 3025 fps | 96.1% |
| SNPE Vectan SP 13 | <<locked>> | 98% | 57,725 psi | 87% | 3084 fps | 98.9% |
| Vihtavuori 20N29ᴾ | <<locked>> | 100% | 55,230 psi | 83% | 3058 fps | 97.3% |
| Vihtavuori N165 | <<locked>> | 84% | 59,103 psi | 89% | 3025 fps | 100% |
| Vihtavuori N170 | <<locked>> | 88% | 59,016 psi | 88% | 3077 fps | 98.7% |
| Vihtavuori N565 | <<locked>> | 84% | 56,956 psi | 85% | 3081 fps | 100% |
| Vihtavuori N568 | <<locked>> | 88% | 59,030 psi | 88% | 3159 fps | 100% |
| Vihtavuori N570 | <<locked>> | 88% | 56,797 psi | 85% | 3169 fps | 99.1% |
| Winchester StaBALL HD | <<locked>> | 82% | 59,843 psi | 90% | 3114 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 82% | 58,653 psi | 88% | 3035 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% | 55,622 psi | 83% | 2956 fps | 100% |
| Accurate 8700 | <<locked>> | 90% | 42,424 psi | 64% | 2822 fps | 96% |
| ADI AR 2213 | <<locked>> | 80% | 54,230 psi | 81% | 3051 fps | 100% |
| ADI AR 2217 | <<locked>> | 80% | 41,814 psi | 63% | 2815 fps | 99.2% |
| ADI AR 2218 | 88.7 gr | 82% | 38,986 psi | 58% | 2831 fps | 95.1% |
| ADI AR 2225 | <<locked>> | 80% | 39,436 psi | 59% | 2799 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 55,274 psi | 83% | 3051 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 80% | 54,128 psi | 81% | 2956 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 48,298 psi | 72% | 2930 fps | 100% |
| Alliant Reloder-33 | 88.1 gr | 80% | 40,785 psi | 61% | 2831 fps | 95.9% |
| Alliant Reloder-50 | <<locked>> | 84% | 42,148 psi | 63% | 2848 fps | 95.7% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 50,734 psi | 76% | 2949 fps | 98.6% |
| Bofors RP15 | <<locked>> | 80% | 51,764 psi | 78% | 2992 fps | 100% |
| Bofors RP30 | <<locked>> | 80% | 45,600 psi | 68% | 2897 fps | 99.7% |
| Bofors RP5 | <<locked>> | 80% | 55,274 psi | 83% | 3051 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 45,266 psi | 68% | 2884 fps | 99.9% |
| Hodgdon H4831 | <<locked>> | 80% | 56,405 psi | 85% | 3038 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 80% | 55,332 psi | 83% | 3022 fps | 99.9% |
| Hodgdon Retumbo | <<locked>> | 80% | 47,834 psi | 72% | 3018 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 29,037 psi | 44% | 1791 fps | 100% |
| Hodgdon US 869 | <<locked>> | 96% | 56,376 psi | 85% | 3068 fps | 95.5% |
| IMR 4955 Enduron | <<locked>> | 80% | 56,072 psi | 84% | 3009 fps | 100% |
| IMR 7828 SSC | <<locked>> | 80% | 53,330 psi | 80% | 3041 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 82% | 48,602 psi | 73% | 2851 fps | 95.1% |
| IMR 8133 Enduron | <<locked>> | 80% | 37,289 psi | 56% | 2730 fps | 98.1% |
| Lovex D100 | <<locked>> | 88% | 53,287 psi | 80% | 2963 fps | 95.3% |
| Lovex S071 | <<locked>> | 80% | 48,573 psi | 73% | 2844 fps | 100% |
| Norma 217 | <<locked>> | 80% | 38,145 psi | 57% | 2759 fps | 99.6% |
| Ramshot Grand | <<locked>> | 80% | 54,839 psi | 82% | 3064 fps | 100% |
| Ramshot LRT | <<locked>> | 92% | 54,824 psi | 82% | 3104 fps | 95.3% |
| Ramshot Magnum | <<locked>> | 80% | 49,922 psi | 75% | 2933 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,892 psi | 45% | 1834 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 48,022 psi | 72% | 2995 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 44,599 psi | 67% | 2904 fps | 98.8% |
| Shooters World 50 BMG | <<locked>> | 88% | 53,287 psi | 80% | 2963 fps | 95.3% |
| SNPE Vectan SP 13 | <<locked>> | 88% | 41,814 psi | 63% | 2782 fps | 95.3% |
| Vihtavuori 20N29 | <<locked>> | 96% | 48,196 psi | 72% | 2933 fps | 95.6% |
| Vihtavuori N165 | <<locked>> | 80% | 52,098 psi | 78% | 2917 fps | 100% |
| Vihtavuori N170 | <<locked>> | 80% | 45,847 psi | 69% | 2838 fps | 95.9% |
| Vihtavuori N565 | <<locked>> | 80% | 50,111 psi | 75% | 2966 fps | 99.8% |
| Vihtavuori N568 | <<locked>> | 80% | 45,150 psi | 68% | 2910 fps | 98.5% |
| Vihtavuori N570 | 84.8 gr | 80% | 43,381 psi | 65% | 2907 fps | 96.2% |
| Winchester StaBALL HD | <<locked>> | 80% | 55,869 psi | 84% | 3058 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 54,882 psi | 82% | 2979 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 44 powders for 7.21 Firebird loaded with the .284 | 160gr | Barnes XLC S. ADI AR 2218 delivers the highest muzzle velocity at 3,255 fps; across all powders the maximum-charge window runs from 1,998 fps to 3,255 fps. Accurate 8700 gives the best case fill at 100 %, and 44 of the 44 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (460 MPa), the top charges use 58–90 %, 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, Alliant Reloder-33 rank at the top here: for 7.21 Firebird with the .284 | 160gr | Barnes XLC S 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.