Load Specifications
Load data in caliber 7.21 Firebird with .284 | 145gr | Speer Boat-Tail 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.
A valid access license is required to use the Personalized Load Calculator.
You can find more information in our FAQ: How can I use the Personalized Load Calculator?
Max Load - Barrel Length: 26"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 3100 | <<locked>> | 84% | 57,261 psi | 86% | 3117 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 53,882 psi | 81% | 3156 fps | 98% |
| Accurate MAGPRO | <<locked>> | 82% | 56,478 psi | 85% | 3232 fps | 99.7% |
| ADI AR 2209 | <<locked>> | 82% | 57,856 psi | 87% | 3209 fps | 100% |
| ADI AR 2213 | <<locked>> | 84% | 57,072 psi | 86% | 3232 fps | 100% |
| ADI AR 2217 | <<locked>> | 92% | 56,898 psi | 85% | 3215 fps | 100% |
| ADI AR 2218 | <<locked>> | 96% | 57,914 psi | 87% | 3353 fps | 99.4% |
| ADI AR 2225 | <<locked>> | 94% | 56,927 psi | 85% | 3238 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 82% | 57,537 psi | 86% | 3199 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 84% | 57,653 psi | 86% | 3225 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 86% | 59,582 psi | 89% | 3176 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 88% | 56,956 psi | 85% | 3202 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 94% | 60,220 psi | 90% | 3323 fps | 99.3% |
| Alliant Reloder-50 | <<locked>> | 96% | 56,391 psi | 85% | 3245 fps | 98.4% |
| Baschieri & Pellagri 109 | <<locked>> | 86% | 57,072 psi | 86% | 3186 fps | 99% |
| Bofors RP15 | <<locked>> | 86% | 57,043 psi | 86% | 3215 fps | 100% |
| Bofors RP30 | <<locked>> | 90% | 56,855 psi | 85% | 3228 fps | 100% |
| Bofors RP5 | <<locked>> | 84% | 57,653 psi | 86% | 3225 fps | 100% |
| Hodgdon H1000 | <<locked>> | 90% | 58,146 psi | 87% | 3232 fps | 100% |
| Hodgdon H4831 | <<locked>> | 84% | 59,292 psi | 89% | 3215 fps | 99.9% |
| Hodgdon H4831 SC | <<locked>> | 84% | 58,349 psi | 87% | 3202 fps | 99.9% |
| Hodgdon Retumbo | <<locked>> | 88% | 56,768 psi | 85% | 3304 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,087 psi | 57% | 2100 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 84% | 59,074 psi | 89% | 3189 fps | 100% |
| IMR 7828 SSC | <<locked>> | 86% | 59,683 psi | 89% | 3278 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 90% | 57,972 psi | 87% | 3143 fps | 96.5% |
| IMR 8133 Enduron | <<locked>> | 98% | 59,712 psi | 90% | 3284 fps | 100% |
| Lovex D100 | <<locked>> | 94% | 59,828 psi | 90% | 3192 fps | 95.9% |
| Lovex S071 | <<locked>> | 90% | 59,495 psi | 89% | 3150 fps | 100% |
| Norma 217 | <<locked>> | 96% | 57,377 psi | 86% | 3245 fps | 100% |
| Norma MRP | <<locked>> | 82% | 57,754 psi | 87% | 3235 fps | 100% |
| Ramshot Grand | <<locked>> | 84% | 57,290 psi | 86% | 3238 fps | 100% |
| Ramshot Magnum | <<locked>> | 88% | 60,046 psi | 90% | 3222 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,015 psi | 58% | 2146 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 88% | 57,943 psi | 87% | 3284 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 90% | 56,869 psi | 85% | 3251 fps | 99.8% |
| Rottweil R 904 | <<locked>> | 82% | 58,073 psi | 87% | 3176 fps | 100% |
| Rottweil R 905 | <<locked>> | 82% | 57,377 psi | 86% | 3189 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 94% | 59,828 psi | 90% | 3192 fps | 95.9% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 55,521 psi | 83% | 3166 fps | 98% |
| SNPE Vectan Tubal 8000 | <<locked>> | 82% | 57,000 psi | 85% | 3186 fps | 100% |
| Somchem S361 | <<locked>> | 82% | 59,509 psi | 89% | 3163 fps | 99.9% |
| Somchem S385 | <<locked>> | 82% | 57,624 psi | 86% | 3153 fps | 100% |
| Vihtavuori N165 | <<locked>> | 86% | 57,943 psi | 87% | 3143 fps | 100% |
| Vihtavuori N170 | <<locked>> | 90% | 57,551 psi | 86% | 3176 fps | 97.8% |
| Vihtavuori N555 | <<locked>> | 82% | 57,450 psi | 86% | 3153 fps | 100% |
| Vihtavuori N560 | <<locked>> | 82% | 57,000 psi | 85% | 3241 fps | 99.9% |
| Vihtavuori N565 | <<locked>> | 88% | 58,726 psi | 88% | 3241 fps | 100% |
| Vihtavuori N568 | <<locked>> | 90% | 57,043 psi | 86% | 3255 fps | 99.6% |
| Vihtavuori N570 | <<locked>> | 92% | 58,784 psi | 88% | 3330 fps | 98.9% |
| Winchester StaBALL HD | <<locked>> | 84% | 57,435 psi | 86% | 3219 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 84% | 57,566 psi | 86% | 3153 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% | 50,067 psi | 75% | 3002 fps | 100% |
| Accurate 8700 | <<locked>> | 94% | 42,989 psi | 64% | 2943 fps | 95% |
| Accurate MAGPRO | <<locked>> | 80% | 52,678 psi | 79% | 3166 fps | 99.3% |
| ADI AR 2209 | <<locked>> | 80% | 54,085 psi | 81% | 3146 fps | 100% |
| ADI AR 2213 | <<locked>> | 80% | 49,516 psi | 74% | 3100 fps | 99.5% |
| ADI AR 2217 | <<locked>> | 80% | 37,115 psi | 56% | 2822 fps | 97.3% |
| ADI AR 2218 | 98.6 gr | 88% | 42,757 psi | 64% | 3035 fps | 95.5% |
| ADI AR 2225 | <<locked>> | 80% | 34,389 psi | 52% | 2789 fps | 98.9% |
| Alliant Reloder-19 | <<locked>> | 80% | 53,867 psi | 81% | 3136 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 50,256 psi | 75% | 3097 fps | 99.9% |
| Alliant Reloder-23 | <<locked>> | 80% | 49,008 psi | 73% | 3012 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 43,091 psi | 65% | 2966 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 86% | 44,556 psi | 67% | 3028 fps | 96.1% |
| Alliant Reloder-50 | <<locked>> | 90% | 44,889 psi | 67% | 3018 fps | 95.6% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 46,905 psi | 70% | 2995 fps | 97.1% |
| Bofors RP15 | <<locked>> | 80% | 46,818 psi | 70% | 3031 fps | 99.6% |
| Bofors RP30 | <<locked>> | 80% | 40,321 psi | 60% | 2904 fps | 98.1% |
| Bofors RP5 | <<locked>> | 80% | 50,256 psi | 75% | 3097 fps | 99.9% |
| Hodgdon H1000 | <<locked>> | 80% | 40,437 psi | 61% | 2904 fps | 98.7% |
| Hodgdon H4831 | <<locked>> | 80% | 51,837 psi | 78% | 3091 fps | 99.4% |
| Hodgdon H4831 SC | <<locked>> | 80% | 50,836 psi | 76% | 3071 fps | 99.3% |
| Hodgdon Retumbo | 84.6 gr | 80% | 42,221 psi | 63% | 3031 fps | 99.7% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,616 psi | 43% | 1883 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 51,967 psi | 78% | 3068 fps | 99.5% |
| IMR 7828 SSC | <<locked>> | 80% | 48,428 psi | 73% | 3084 fps | 99.4% |
| IMR 7977 Enduron | <<locked>> | 88% | 54,288 psi | 81% | 3077 fps | 95.6% |
| IMR 8133 Enduron | <<locked>> | 82% | 34,345 psi | 51% | 2766 fps | 95.9% |
| Lovex D100 | <<locked>> | 92% | 55,782 psi | 84% | 3127 fps | 95% |
| Lovex S071 | <<locked>> | 80% | 43,120 psi | 65% | 2874 fps | 100% |
| Norma 217 | <<locked>> | 80% | 32,518 psi | 49% | 2730 fps | 97.3% |
| Norma MRP | <<locked>> | 80% | 53,824 psi | 81% | 3173 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 49,255 psi | 74% | 3100 fps | 99.7% |
| Ramshot Magnum | <<locked>> | 80% | 44,599 psi | 67% | 2959 fps | 99.8% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,370 psi | 44% | 1926 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 42,221 psi | 63% | 3005 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 38,827 psi | 58% | 2884 fps | 96.2% |
| Rottweil R 904 | <<locked>> | 80% | 54,360 psi | 81% | 3117 fps | 99.9% |
| Rottweil R 905 | <<locked>> | 80% | 53,635 psi | 80% | 3130 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 92% | 55,782 psi | 84% | 3127 fps | 95% |
| SNPE Vectan SP 13 | <<locked>> | 94% | 45,136 psi | 68% | 2966 fps | 95.3% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 53,287 psi | 80% | 3123 fps | 100% |
| Somchem S361 | <<locked>> | 80% | 55,738 psi | 84% | 3104 fps | 99.8% |
| Somchem S385 | <<locked>> | 80% | 53,983 psi | 81% | 3094 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 47,485 psi | 71% | 2969 fps | 99.9% |
| Vihtavuori N170 | <<locked>> | 84% | 46,905 psi | 70% | 2976 fps | 95.2% |
| Vihtavuori N555 | <<locked>> | 80% | 53,795 psi | 81% | 3094 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 53,127 psi | 80% | 3176 fps | 99.6% |
| Vihtavuori N565 | <<locked>> | 80% | 44,730 psi | 67% | 2982 fps | 98.6% |
| Vihtavuori N568 | <<locked>> | 80% | 39,769 psi | 60% | 2904 fps | 96% |
| Vihtavuori N570 | 92.2 gr | 84% | 43,874 psi | 66% | 3035 fps | 95.3% |
| Winchester StaBALL HD | <<locked>> | 80% | 49,284 psi | 74% | 3094 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 50,125 psi | 75% | 3028 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 57 powders for 7.21 Firebird loaded with the .284 | 145gr | Speer Boat-Tail. ADI AR 2218 delivers the highest muzzle velocity at 3,353 fps; across all powders the maximum-charge window runs from 2,100 fps to 3,353 fps. Accurate 8700 gives the best case fill at 100 %, and 57 of the 57 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 145.0 gr projectile in 0.284" calls for a 1:12.0 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 | 145gr | Speer Boat-Tail they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Hodgdon 50BMG, 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.