Load Specifications
Load data in caliber 7.21 Firebird with .284 | 158gr | Sellier & Bellot XRG 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 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>> | 84% | 58,798 psi | 88% | 3031 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 55,738 psi | 84% | 3091 fps | 98.9% |
| Accurate MAGPRO | <<locked>> | 82% | 58,102 psi | 87% | 3153 fps | 100% |
| ADI AR 2209 | <<locked>> | 82% | 59,422 psi | 89% | 3120 fps | 100% |
| ADI AR 2213 | <<locked>> | 84% | 58,537 psi | 88% | 3143 fps | 100% |
| ADI AR 2217 | <<locked>> | 92% | 58,508 psi | 88% | 3133 fps | 100% |
| ADI AR 2218 | <<locked>> | 96% | 59,741 psi | 90% | 3281 fps | 99.8% |
| ADI AR 2225 | <<locked>> | 94% | 58,639 psi | 88% | 3156 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 82% | 59,045 psi | 89% | 3110 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 84% | 59,074 psi | 89% | 3136 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 84% | 57,421 psi | 86% | 3031 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 88% | 58,668 psi | 88% | 3117 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 92% | 57,595 psi | 86% | 3179 fps | 99.4% |
| Alliant Reloder-50 | <<locked>> | 96% | 58,073 psi | 87% | 3179 fps | 99.2% |
| Baschieri & Pellagri 109 | <<locked>> | 86% | 58,450 psi | 88% | 3104 fps | 99.5% |
| Bofors RP15 | <<locked>> | 86% | 58,653 psi | 88% | 3130 fps | 100% |
| Bofors RP30 | <<locked>> | 90% | 58,523 psi | 88% | 3146 fps | 100% |
| Bofors RP5 | <<locked>> | 84% | 59,074 psi | 89% | 3136 fps | 100% |
| Hodgdon H1000 | <<locked>> | 90% | 59,973 psi | 90% | 3150 fps | 100% |
| Hodgdon H4831 | <<locked>> | 82% | 56,869 psi | 85% | 3071 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 84% | 59,712 psi | 90% | 3114 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 88% | 58,827 psi | 88% | 3222 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,101 psi | 57% | 2008 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 82% | 56,782 psi | 85% | 3045 fps | 100% |
| IMR 7828 SSC | <<locked>> | 84% | 57,377 psi | 86% | 3133 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 90% | 59,248 psi | 89% | 3061 fps | 97.4% |
| IMR 8133 Enduron | <<locked>> | 96% | 57,493 psi | 86% | 3143 fps | 100% |
| Lovex D100 | <<locked>> | 92% | 57,188 psi | 86% | 3054 fps | 96% |
| Lovex S071 | <<locked>> | 88% | 57,276 psi | 86% | 3009 fps | 100% |
| Norma 217 | <<locked>> | 96% | 59,379 psi | 89% | 3166 fps | 100% |
| Norma MRP | <<locked>> | 82% | 59,524 psi | 89% | 3150 fps | 100% |
| Ramshot Grand | <<locked>> | 84% | 59,103 psi | 89% | 3156 fps | 100% |
| Ramshot LRT | <<locked>> | 96% | 59,045 psi | 89% | 3199 fps | 96.2% |
| Ramshot Magnum | <<locked>> | 86% | 57,479 psi | 86% | 3077 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,218 psi | 59% | 2057 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 88% | 59,785 psi | 90% | 3202 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 90% | 58,740 psi | 88% | 3179 fps | 100% |
| Rottweil R 904 | <<locked>> | 82% | 59,480 psi | 89% | 3091 fps | 100% |
| Rottweil R 905 | <<locked>> | 82% | 58,929 psi | 88% | 3100 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 92% | 57,188 psi | 86% | 3054 fps | 96% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 57,290 psi | 86% | 3097 fps | 98.8% |
| SNPE Vectan Tubal 8000 | <<locked>> | 82% | 58,566 psi | 88% | 3100 fps | 100% |
| Somchem S385 | <<locked>> | 82% | 59,205 psi | 89% | 3068 fps | 100% |
| Vihtavuori 20N29ᴾ | <<locked>> | 100% | 50,618 psi | 76% | 2999 fps | 96.1% |
| Vihtavuori N165 | <<locked>> | 86% | 59,350 psi | 89% | 3054 fps | 100% |
| Vihtavuori N170 | <<locked>> | 90% | 59,074 psi | 89% | 3100 fps | 98.6% |
| Vihtavuori N555 | <<locked>> | 82% | 59,045 psi | 89% | 3061 fps | 100% |
| Vihtavuori N560 | <<locked>> | 82% | 58,682 psi | 88% | 3163 fps | 100% |
| Vihtavuori N565 | <<locked>> | 86% | 56,463 psi | 85% | 3100 fps | 100% |
| Vihtavuori N568 | <<locked>> | 90% | 58,871 psi | 88% | 3179 fps | 99.9% |
| Vihtavuori N570 | <<locked>> | 90% | 56,507 psi | 85% | 3189 fps | 99% |
| Winchester StaBALL HD | <<locked>> | 84% | 59,451 psi | 89% | 3130 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 84% | 59,190 psi | 89% | 3068 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% | 51,430 psi | 77% | 2920 fps | 100% |
| Accurate 8700 | <<locked>> | 92% | 41,408 psi | 62% | 2818 fps | 95.3% |
| Accurate MAGPRO | <<locked>> | 80% | 54,273 psi | 81% | 3091 fps | 99.8% |
| ADI AR 2209 | <<locked>> | 80% | 55,637 psi | 83% | 3061 fps | 100% |
| ADI AR 2213 | <<locked>> | 80% | 50,995 psi | 76% | 3022 fps | 99.9% |
| ADI AR 2217 | <<locked>> | 80% | 38,276 psi | 57% | 2756 fps | 98.3% |
| ADI AR 2218 | 93.6 gr | 86% | 41,104 psi | 62% | 2904 fps | 95.8% |
| ADI AR 2225 | <<locked>> | 80% | 35,752 psi | 54% | 2733 fps | 99.7% |
| Alliant Reloder-19 | <<locked>> | 80% | 55,259 psi | 83% | 3051 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 51,721 psi | 78% | 3018 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 80% | 50,343 psi | 75% | 2927 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 44,657 psi | 67% | 2890 fps | 100% |
| Alliant Reloder-33 | 90.9 gr | 82% | 39,653 psi | 59% | 2825 fps | 95.1% |
| Alliant Reloder-50 | <<locked>> | 88% | 43,192 psi | 65% | 2894 fps | 95.9% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 48,124 psi | 72% | 2923 fps | 98% |
| Bofors RP15 | <<locked>> | 80% | 48,124 psi | 72% | 2953 fps | 99.9% |
| Bofors RP30 | <<locked>> | 80% | 41,684 psi | 62% | 2838 fps | 99% |
| Bofors RP5 | <<locked>> | 80% | 51,721 psi | 78% | 3018 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 41,800 psi | 63% | 2838 fps | 99.4% |
| Hodgdon H4831 | <<locked>> | 80% | 53,084 psi | 80% | 3009 fps | 99.8% |
| Hodgdon H4831 SC | <<locked>> | 80% | 52,199 psi | 78% | 2992 fps | 99.7% |
| Hodgdon Retumbo | <<locked>> | 80% | 43,990 psi | 66% | 2966 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,631 psi | 43% | 1801 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 53,316 psi | 80% | 2989 fps | 99.9% |
| IMR 7828 SSC | <<locked>> | 80% | 49,908 psi | 75% | 3005 fps | 99.8% |
| IMR 7977 Enduron | <<locked>> | 84% | 48,892 psi | 73% | 2881 fps | 95% |
| IMR 8133 Enduron | <<locked>> | 80% | 33,199 psi | 50% | 2648 fps | 96.3% |
| Lovex D100 | <<locked>> | 90% | 53,258 psi | 80% | 2989 fps | 95.1% |
| Lovex S071 | <<locked>> | 80% | 44,440 psi | 67% | 2799 fps | 100% |
| Norma 217 | <<locked>> | 80% | 33,939 psi | 51% | 2677 fps | 98.6% |
| Norma MRP | <<locked>> | 80% | 55,579 psi | 83% | 3091 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 51,024 psi | 76% | 3028 fps | 100% |
| Ramshot LRT | <<locked>> | 94% | 55,056 psi | 83% | 3130 fps | 95.2% |
| Ramshot Magnum | <<locked>> | 80% | 45,948 psi | 69% | 2887 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,544 psi | 44% | 1844 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 43,816 psi | 66% | 2940 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 40,234 psi | 60% | 2831 fps | 97.5% |
| Rottweil R 904 | <<locked>> | 80% | 55,767 psi | 84% | 3031 fps | 100% |
| Rottweil R 905 | <<locked>> | 80% | 55,201 psi | 83% | 3045 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 90% | 53,258 psi | 80% | 2989 fps | 95.1% |
| SNPE Vectan SP 13 | <<locked>> | 92% | 43,395 psi | 65% | 2841 fps | 95.6% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 54,853 psi | 82% | 3041 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 55,390 psi | 83% | 3009 fps | 100% |
| Vihtavuori 20N29 | <<locked>> | 98% | 46,992 psi | 70% | 2930 fps | 95% |
| Vihtavuori N165 | <<locked>> | 80% | 48,776 psi | 73% | 2890 fps | 100% |
| Vihtavuori N170 | <<locked>> | 82% | 45,092 psi | 68% | 2848 fps | 95.5% |
| Vihtavuori N555 | <<locked>> | 80% | 55,347 psi | 83% | 3009 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 54,810 psi | 82% | 3097 fps | 99.9% |
| Vihtavuori N565 | <<locked>> | 80% | 46,006 psi | 69% | 2913 fps | 99.3% |
| Vihtavuori N568 | <<locked>> | 80% | 41,162 psi | 62% | 2848 fps | 97.3% |
| Vihtavuori N570 | 87.4 gr | 82% | 42,322 psi | 63% | 2907 fps | 95.7% |
| Winchester StaBALL HD | <<locked>> | 80% | 51,285 psi | 77% | 3015 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 51,532 psi | 77% | 2949 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 53 powders for 7.21 Firebird loaded with the .284 | 158gr | Sellier & Bellot XRG. ADI AR 2218 delivers the highest muzzle velocity at 3,281 fps; across all powders the maximum-charge window runs from 2,008 fps to 3,281 fps. Accurate 8700 gives the best case fill at 100 %, and 53 of the 53 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 158.0 gr projectile in 0.284" calls for a 1:10.5 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, Alliant Reloder-33 rank at the top here: for 7.21 Firebird with the .284 | 158gr | Sellier & Bellot XRG 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.