Load Specifications
Load data in caliber 7.21 Firebird with .284 | 140gr | NorthFork Bonded Core 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, Hodgdon Retumbo and Vihtavuori N570.
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% | 58,885 psi | 88% | 3186 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 51,010 psi | 76% | 3143 fps | 97% |
| Accurate MAGPRO | <<locked>> | 84% | 58,146 psi | 87% | 3304 fps | 99.6% |
| ADI AR 2209 | <<locked>> | 84% | 59,582 psi | 89% | 3281 fps | 100% |
| ADI AR 2213 | <<locked>> | 86% | 58,726 psi | 88% | 3301 fps | 100% |
| ADI AR 2217 | <<locked>> | 94% | 58,175 psi | 87% | 3278 fps | 100% |
| ADI AR 2218 | <<locked>> | 98% | 59,466 psi | 89% | 3422 fps | 99.3% |
| ADI AR 2225 | <<locked>> | 96% | 57,957 psi | 87% | 3301 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 84% | 59,161 psi | 89% | 3268 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 86% | 59,234 psi | 89% | 3294 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 86% | 57,406 psi | 86% | 3189 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 90% | 58,218 psi | 87% | 3271 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 82% | 58,334 psi | 87% | 3281 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 94% | 57,276 psi | 86% | 3320 fps | 98.7% |
| Alliant Reloder-50 | <<locked>> | 98% | 57,435 psi | 86% | 3307 fps | 98.3% |
| Baschieri & Pellagri 109 | <<locked>> | 88% | 58,769 psi | 88% | 3251 fps | 99% |
| Bofors RP15 | <<locked>> | 88% | 58,581 psi | 88% | 3284 fps | 100% |
| Bofors RP30 | <<locked>> | 92% | 58,146 psi | 87% | 3294 fps | 100% |
| Bofors RP5 | <<locked>> | 86% | 59,234 psi | 89% | 3294 fps | 100% |
| Hodgdon H1000 | <<locked>> | 92% | 59,872 psi | 90% | 3304 fps | 100% |
| Hodgdon H4831 | <<locked>> | 84% | 57,116 psi | 86% | 3225 fps | 99.7% |
| Hodgdon H4831 SC | <<locked>> | 86% | 60,133 psi | 90% | 3274 fps | 99.9% |
| Hodgdon Hybrid 100V | <<locked>> | 82% | 59,770 psi | 90% | 3173 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 90% | 58,030 psi | 87% | 3373 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,840 psi | 57% | 2123 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 84% | 57,101 psi | 86% | 3199 fps | 99.8% |
| IMR 7828 SSC | <<locked>> | 86% | 57,246 psi | 86% | 3284 fps | 99.9% |
| IMR 7977 Enduron | <<locked>> | 92% | 59,770 psi | 90% | 3205 fps | 96.3% |
| IMR 8133 Enduron | <<locked>> | 98% | 56,782 psi | 85% | 3284 fps | 100% |
| Lovex S071 | <<locked>> | 90% | 57,203 psi | 86% | 3159 fps | 100% |
| Norma 217 | <<locked>> | 98% | 58,407 psi | 88% | 3307 fps | 100% |
| Norma MRP | <<locked>> | 84% | 59,480 psi | 89% | 3307 fps | 100% |
| Ramshot Grand | <<locked>> | 86% | 58,871 psi | 88% | 3310 fps | 100% |
| Ramshot Magnum | <<locked>> | 88% | 57,363 psi | 86% | 3228 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,899 psi | 58% | 2172 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 90% | 59,161 psi | 89% | 3353 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 92% | 58,349 psi | 87% | 3320 fps | 99.8% |
| Rottweil R 904 | <<locked>> | 84% | 59,828 psi | 90% | 3248 fps | 100% |
| Rottweil R 905 | <<locked>> | 84% | 59,205 psi | 89% | 3264 fps | 100% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 52,968 psi | 79% | 3159 fps | 97.1% |
| SNPE Vectan Tubal 8000 | <<locked>> | 84% | 58,813 psi | 88% | 3258 fps | 100% |
| Somchem S361 | <<locked>> | 82% | 57,580 psi | 86% | 3173 fps | 99.8% |
| Somchem S385 | <<locked>> | 84% | 59,422 psi | 89% | 3222 fps | 100% |
| Vihtavuori N165 | <<locked>> | 88% | 59,669 psi | 89% | 3209 fps | 100% |
| Vihtavuori N170 | <<locked>> | 92% | 59,335 psi | 89% | 3245 fps | 97.7% |
| Vihtavuori N555 | <<locked>> | 84% | 58,958 psi | 88% | 3219 fps | 100% |
| Vihtavuori N560 | <<locked>> | 84% | 58,682 psi | 88% | 3317 fps | 99.9% |
| Vihtavuori N565 | <<locked>> | 90% | 60,336 psi | 90% | 3310 fps | 100% |
| Vihtavuori N568 | <<locked>> | 92% | 58,537 psi | 88% | 3323 fps | 99.6% |
| Vihtavuori N570 | <<locked>> | 94% | 60,118 psi | 90% | 3396 fps | 98.8% |
| Winchester StaBALL HD | <<locked>> | 86% | 58,682 psi | 88% | 3287 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 86% | 59,364 psi | 89% | 3222 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% | 48,095 psi | 72% | 3012 fps | 100% |
| Accurate 8700 | <<locked>> | 98% | 47,398 psi | 71% | 3074 fps | 96% |
| Accurate MAGPRO | <<locked>> | 80% | 50,430 psi | 76% | 3163 fps | 98.7% |
| ADI AR 2209 | <<locked>> | 80% | 52,098 psi | 78% | 3156 fps | 99.9% |
| ADI AR 2213 | <<locked>> | 80% | 47,500 psi | 71% | 3100 fps | 99% |
| ADI AR 2217 | <<locked>> | 80% | 35,476 psi | 53% | 2815 fps | 96.1% |
| ADI AR 2218 | 99.4 gr | 90% | 43,845 psi | 66% | 3097 fps | 95.4% |
| ADI AR 2225 | <<locked>> | 80% | 32,779 psi | 49% | 2782 fps | 98.1% |
| Alliant Reloder-19 | <<locked>> | 80% | 51,967 psi | 78% | 3146 fps | 99.9% |
| Alliant Reloder-22 | <<locked>> | 80% | 48,269 psi | 72% | 3100 fps | 99.7% |
| Alliant Reloder-23 | <<locked>> | 80% | 46,963 psi | 70% | 3025 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 41,104 psi | 62% | 2969 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 80% | 54,201 psi | 81% | 3219 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 88% | 45,527 psi | 68% | 3091 fps | 95.9% |
| Alliant Reloder-50 | <<locked>> | 92% | 45,818 psi | 69% | 3081 fps | 95.4% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 45,179 psi | 68% | 2995 fps | 96.1% |
| Bofors RP15 | <<locked>> | 80% | 44,918 psi | 67% | 3031 fps | 99.2% |
| Bofors RP30 | <<locked>> | 80% | 38,450 psi | 58% | 2900 fps | 97.2% |
| Bofors RP5 | <<locked>> | 80% | 48,269 psi | 72% | 3100 fps | 99.7% |
| Hodgdon H1000 | <<locked>> | 80% | 38,653 psi | 58% | 2900 fps | 97.9% |
| Hodgdon H4831 | <<locked>> | 80% | 49,821 psi | 75% | 3094 fps | 98.9% |
| Hodgdon H4831 SC | <<locked>> | 80% | 48,994 psi | 73% | 3077 fps | 98.8% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 56,043 psi | 84% | 3120 fps | 100% |
| Hodgdon Retumbo | 83.4 gr | 80% | 40,176 psi | 60% | 3025 fps | 99.2% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,529 psi | 43% | 1906 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 50,270 psi | 75% | 3077 fps | 99.1% |
| IMR 7828 SSC | <<locked>> | 80% | 46,209 psi | 69% | 3081 fps | 98.8% |
| IMR 7977 Enduron | <<locked>> | 90% | 55,927 psi | 84% | 3143 fps | 95.5% |
| IMR 8133 Enduron | <<locked>> | 84% | 34,954 psi | 52% | 2822 fps | 95.7% |
| Lovex S071 | <<locked>> | 80% | 41,452 psi | 62% | 2881 fps | 99.9% |
| Norma 217 | <<locked>> | 80% | 30,705 psi | 46% | 2717 fps | 96% |
| Norma MRP | <<locked>> | 80% | 51,663 psi | 77% | 3179 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 47,021 psi | 70% | 3100 fps | 99.2% |
| Ramshot Magnum | <<locked>> | 80% | 42,453 psi | 64% | 2959 fps | 99.5% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,254 psi | 44% | 1952 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 39,972 psi | 60% | 2999 fps | 99.7% |
| ReloadSwiss RS 80 | <<locked>> | 82% | 39,827 psi | 60% | 2953 fps | 96.2% |
| Rottweil R 904 | <<locked>> | 80% | 52,518 psi | 79% | 3123 fps | 99.6% |
| Rottweil R 905 | <<locked>> | 80% | 51,634 psi | 77% | 3136 fps | 99.9% |
| SNPE Vectan SP 13 | <<locked>> | 96% | 45,948 psi | 69% | 3022 fps | 95.1% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 51,300 psi | 77% | 3133 fps | 99.9% |
| Somchem S361 | <<locked>> | 80% | 53,838 psi | 81% | 3110 fps | 99.4% |
| Somchem S385 | <<locked>> | 80% | 52,083 psi | 78% | 3107 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 45,716 psi | 69% | 2976 fps | 99.7% |
| Vihtavuori N170 | <<locked>> | 86% | 48,327 psi | 72% | 3045 fps | 95.2% |
| Vihtavuori N555 | <<locked>> | 80% | 51,677 psi | 77% | 3107 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 51,053 psi | 77% | 3179 fps | 99.2% |
| Vihtavuori N565 | <<locked>> | 80% | 42,685 psi | 64% | 2979 fps | 97.7% |
| Vihtavuori N568 | <<locked>> | 82% | 40,683 psi | 61% | 2969 fps | 95.8% |
| Vihtavuori N570 | 93.1 gr | 86% | 44,976 psi | 67% | 3100 fps | 95.2% |
| Winchester StaBALL HD | <<locked>> | 80% | 46,789 psi | 70% | 3100 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 48,283 psi | 72% | 3035 fps | 99.7% |
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 | 140gr | NorthFork Bonded Core. ADI AR 2218 delivers the highest muzzle velocity at 3,422 fps; across all powders the maximum-charge window runs from 2,123 fps to 3,422 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 140.0 gr projectile in 0.284" calls for a 1:11.0 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, Hodgdon Retumbo, Vihtavuori N570 rank at the top here: for 7.21 Firebird with the .284 | 140gr | NorthFork Bonded Core they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Hodgdon 50BMG, Hodgdon US 869, Lovex D100 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.