Load Specifications
Load data in caliber 7.21 Firebird with .284 | 152gr | Barnes LRX BT bullet and 52 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>> | 86% | 58,769 psi | 88% | 3084 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 50,995 psi | 76% | 3061 fps | 97.6% |
| Accurate MAGPRO | <<locked>> | 84% | 58,276 psi | 87% | 3209 fps | 99.9% |
| ADI AR 2209 | <<locked>> | 84% | 59,915 psi | 90% | 3182 fps | 100% |
| ADI AR 2213 | <<locked>> | 86% | 58,914 psi | 88% | 3205 fps | 100% |
| ADI AR 2217 | <<locked>> | 94% | 58,552 psi | 88% | 3186 fps | 100% |
| ADI AR 2218 | <<locked>> | 98% | 59,698 psi | 89% | 3333 fps | 99.6% |
| ADI AR 2225 | <<locked>> | 96% | 58,073 psi | 87% | 3205 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 84% | 59,480 psi | 89% | 3173 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 86% | 59,248 psi | 89% | 3192 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 86% | 57,435 psi | 86% | 3087 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 90% | 58,465 psi | 88% | 3169 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 82% | 58,363 psi | 87% | 3179 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 94% | 57,145 psi | 86% | 3225 fps | 99.1% |
| Alliant Reloder-50 | <<locked>> | 98% | 57,276 psi | 86% | 3215 fps | 98.8% |
| Baschieri & Pellagri 109 | <<locked>> | 88% | 59,088 psi | 89% | 3163 fps | 99.4% |
| Bofors RP15 | <<locked>> | 88% | 58,610 psi | 88% | 3182 fps | 100% |
| Bofors RP30 | <<locked>> | 92% | 58,233 psi | 87% | 3196 fps | 100% |
| Bofors RP5 | <<locked>> | 86% | 59,248 psi | 89% | 3192 fps | 100% |
| Hodgdon H1000 | <<locked>> | 92% | 60,046 psi | 90% | 3202 fps | 100% |
| Hodgdon H4831 | <<locked>> | 84% | 57,290 psi | 86% | 3130 fps | 99.9% |
| Hodgdon H4831 SC | <<locked>> | 86% | 60,278 psi | 90% | 3176 fps | 100% |
| Hodgdon Hybrid 100V | <<locked>> | 82% | 59,944 psi | 90% | 3068 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 90% | 58,320 psi | 87% | 3274 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,927 psi | 57% | 2037 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 84% | 57,363 psi | 86% | 3107 fps | 99.9% |
| IMR 7828 SSC | <<locked>> | 86% | 57,348 psi | 86% | 3186 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 92% | 59,930 psi | 90% | 3117 fps | 97% |
| IMR 8133 Enduron | <<locked>> | 98% | 56,840 psi | 85% | 3186 fps | 100% |
| Lovex S071 | <<locked>> | 90% | 56,985 psi | 85% | 3058 fps | 100% |
| Norma 217 | <<locked>> | 98% | 58,334 psi | 87% | 3205 fps | 100% |
| Norma MRP | <<locked>> | 84% | 59,553 psi | 89% | 3205 fps | 100% |
| Ramshot Grand | <<locked>> | 86% | 59,176 psi | 89% | 3212 fps | 100% |
| Ramshot Magnum | <<locked>> | 88% | 57,522 psi | 86% | 3130 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,841 psi | 58% | 2083 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 90% | 59,495 psi | 89% | 3258 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 92% | 58,262 psi | 87% | 3225 fps | 99.9% |
| Rottweil R 904 | <<locked>> | 84% | 60,104 psi | 90% | 3150 fps | 100% |
| Rottweil R 905 | <<locked>> | 84% | 59,248 psi | 89% | 3159 fps | 100% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 52,707 psi | 79% | 3068 fps | 97.6% |
| SNPE Vectan Tubal 8000 | <<locked>> | 84% | 58,871 psi | 88% | 3159 fps | 100% |
| Somchem S361 | <<locked>> | 82% | 57,580 psi | 86% | 3077 fps | 99.9% |
| Somchem S385 | <<locked>> | 84% | 59,451 psi | 89% | 3123 fps | 100% |
| Vihtavuori N165 | <<locked>> | 88% | 59,756 psi | 90% | 3114 fps | 100% |
| Vihtavuori N170 | <<locked>> | 92% | 59,161 psi | 89% | 3150 fps | 98.2% |
| Vihtavuori N555 | <<locked>> | 84% | 58,914 psi | 88% | 3117 fps | 100% |
| Vihtavuori N560 | <<locked>> | 84% | 58,827 psi | 88% | 3219 fps | 100% |
| Vihtavuori N565 | <<locked>> | 90% | 60,147 psi | 90% | 3209 fps | 100% |
| Vihtavuori N568 | <<locked>> | 92% | 58,508 psi | 88% | 3228 fps | 99.8% |
| Vihtavuori N570 | <<locked>> | 94% | 60,278 psi | 90% | 3304 fps | 99.2% |
| Winchester StaBALL HD | <<locked>> | 86% | 58,900 psi | 88% | 3186 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 86% | 59,451 psi | 89% | 3123 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% | 47,703 psi | 72% | 2910 fps | 100% |
| Accurate 8700 | <<locked>> | 96% | 43,729 psi | 66% | 2917 fps | 95.6% |
| Accurate MAGPRO | <<locked>> | 80% | 50,401 psi | 76% | 3071 fps | 99.1% |
| ADI AR 2209 | <<locked>> | 80% | 52,301 psi | 78% | 3061 fps | 100% |
| ADI AR 2213 | <<locked>> | 80% | 47,587 psi | 71% | 3009 fps | 99.4% |
| ADI AR 2217 | <<locked>> | 80% | 35,346 psi | 53% | 2733 fps | 96.9% |
| ADI AR 2218 | 96.4 gr | 90% | 43,816 psi | 66% | 3015 fps | 96.3% |
| ADI AR 2225 | <<locked>> | 80% | 32,605 psi | 49% | 2697 fps | 98.6% |
| Alliant Reloder-19 | <<locked>> | 80% | 51,967 psi | 78% | 3048 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 48,211 psi | 72% | 3009 fps | 99.9% |
| Alliant Reloder-23 | <<locked>> | 80% | 46,905 psi | 70% | 2927 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 41,118 psi | 62% | 2877 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 80% | 54,230 psi | 81% | 3117 fps | 100% |
| Alliant Reloder-33 | 93.8 gr | 86% | 42,018 psi | 63% | 2930 fps | 95.5% |
| Alliant Reloder-50 | <<locked>> | 92% | 45,353 psi | 68% | 2989 fps | 96% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 45,237 psi | 68% | 2910 fps | 96.9% |
| Bofors RP15 | <<locked>> | 80% | 44,875 psi | 67% | 2940 fps | 99.5% |
| Bofors RP30 | <<locked>> | 80% | 38,174 psi | 57% | 2808 fps | 97.8% |
| Bofors RP5 | <<locked>> | 80% | 48,211 psi | 72% | 3009 fps | 99.9% |
| Hodgdon H1000 | <<locked>> | 80% | 38,522 psi | 58% | 2812 fps | 98.5% |
| Hodgdon H4831 | <<locked>> | 80% | 49,850 psi | 75% | 2999 fps | 99.3% |
| Hodgdon H4831 SC | <<locked>> | 80% | 49,008 psi | 73% | 2986 fps | 99.2% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 56,057 psi | 84% | 3015 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 80% | 40,248 psi | 60% | 2936 fps | 99.6% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,427 psi | 43% | 1827 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 50,386 psi | 76% | 2986 fps | 99.5% |
| IMR 7828 SSC | <<locked>> | 80% | 46,383 psi | 70% | 2992 fps | 99.2% |
| IMR 7977 Enduron | <<locked>> | 88% | 52,504 psi | 79% | 2992 fps | 95.4% |
| IMR 8133 Enduron | <<locked>> | 82% | 32,358 psi | 49% | 2671 fps | 95.3% |
| Lovex S071 | <<locked>> | 80% | 41,060 psi | 62% | 2782 fps | 100% |
| Norma 217 | <<locked>> | 80% | 30,385 psi | 46% | 2628 fps | 96.7% |
| Norma MRP | <<locked>> | 80% | 51,590 psi | 77% | 3081 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 47,007 psi | 70% | 3005 fps | 99.5% |
| Ramshot Magnum | <<locked>> | 80% | 42,322 psi | 63% | 2871 fps | 99.7% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,167 psi | 44% | 1867 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 39,914 psi | 60% | 2910 fps | 99.9% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 36,564 psi | 55% | 2789 fps | 95.7% |
| Rottweil R 904 | <<locked>> | 80% | 52,649 psi | 79% | 3028 fps | 99.8% |
| Rottweil R 905 | <<locked>> | 80% | 51,706 psi | 78% | 3041 fps | 100% |
| SNPE Vectan SP 13 | <<locked>> | 96% | 45,759 psi | 69% | 2936 fps | 95.8% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 51,372 psi | 77% | 3035 fps | 100% |
| Somchem S361 | <<locked>> | 80% | 53,867 psi | 81% | 3018 fps | 99.7% |
| Somchem S385 | <<locked>> | 80% | 51,967 psi | 78% | 3005 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 45,571 psi | 68% | 2881 fps | 99.9% |
| Vihtavuori N170 | <<locked>> | 86% | 48,080 psi | 72% | 2953 fps | 95.9% |
| Vihtavuori N555 | <<locked>> | 80% | 51,663 psi | 77% | 3009 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 51,039 psi | 77% | 3084 fps | 99.5% |
| Vihtavuori N565 | <<locked>> | 80% | 42,453 psi | 64% | 2887 fps | 98.3% |
| Vihtavuori N568 | <<locked>> | 80% | 37,652 psi | 56% | 2808 fps | 95.5% |
| Vihtavuori N570 | 90.2 gr | 86% | 44,817 psi | 67% | 3012 fps | 96% |
| Winchester StaBALL HD | <<locked>> | 80% | 46,804 psi | 70% | 3002 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 48,283 psi | 72% | 2943 fps | 99.9% |
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 59 powders for 7.21 Firebird loaded with the .284 | 152gr | Barnes LRX BT. ADI AR 2218 delivers the highest muzzle velocity at 3,333 fps; across all powders the maximum-charge window runs from 2,037 fps to 3,333 fps. Accurate 8700 gives the best case fill at 100 %, and 59 of the 59 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 152.0 gr projectile in 0.284" calls for a 1:9.0 twist; slower twists will usually not stabilise this weight. Accurate 8700, Hodgdon TrailBoss, Hodgdon US 869 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 | 152gr | Barnes LRX BT they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Hodgdon 50BMG, Hodgdon US 869, Vihtavuori 20N29 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.