Load Specifications
Load data in caliber 7.21 Firebird with .285 | 173gr | Prvi Partizan FMJ BT bullet and 42 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 Ramshot LRT.
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>> | 82% | 59,103 psi | 89% | 2917 fps | 100% |
| Accurate 8700 | <<locked>> | 98% | 57,145 psi | 86% | 3005 fps | 99.6% |
| ADI AR 2213 | <<locked>> | 82% | 58,958 psi | 88% | 3031 fps | 100% |
| ADI AR 2217 | <<locked>> | 90% | 59,611 psi | 89% | 3031 fps | 100% |
| ADI AR 2218 | <<locked>> | 92% | 56,855 psi | 85% | 3123 fps | 99.9% |
| ADI AR 2225 | <<locked>> | 92% | 60,191 psi | 90% | 3051 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 82% | 59,509 psi | 89% | 3022 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 82% | 58,059 psi | 87% | 2920 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 86% | 59,611 psi | 89% | 3005 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 90% | 58,914 psi | 88% | 3087 fps | 99.9% |
| Alliant Reloder-50 | <<locked>> | 94% | 59,640 psi | 89% | 3094 fps | 99.7% |
| Baschieri & Pellagri 109 | <<locked>> | 84% | 58,552 psi | 88% | 2995 fps | 99.9% |
| Bofors RP15 | <<locked>> | 84% | 59,088 psi | 89% | 3018 fps | 100% |
| Bofors RP30 | <<locked>> | 88% | 59,495 psi | 89% | 3041 fps | 100% |
| Bofors RP5 | <<locked>> | 82% | 59,509 psi | 89% | 3022 fps | 100% |
| Hodgdon H1000 | <<locked>> | 86% | 56,666 psi | 85% | 2982 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 82% | 59,814 psi | 90% | 3002 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 86% | 60,118 psi | 90% | 3114 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,319 psi | 57% | 1936 fps | 100% |
| Hodgdon US 869 | <<locked>> | 96% | 57,377 psi | 86% | 3009 fps | 96.7% |
| IMR 7828 SSC | <<locked>> | 82% | 57,914 psi | 87% | 3022 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 88% | 59,248 psi | 89% | 2959 fps | 98.2% |
| IMR 8133 Enduron | <<locked>> | 94% | 58,871 psi | 88% | 3048 fps | 100% |
| Lovex D100 | <<locked>> | 90% | 57,740 psi | 87% | 2963 fps | 97.2% |
| Lovex S071 | <<locked>> | 86% | 57,783 psi | 87% | 2900 fps | 100% |
| Norma 217 | <<locked>> | 92% | 56,884 psi | 85% | 3009 fps | 100% |
| Ramshot Grand | <<locked>> | 82% | 59,872 psi | 90% | 3048 fps | 100% |
| Ramshot LRT | <<locked>> | 94% | 60,075 psi | 90% | 3110 fps | 97.4% |
| Ramshot Magnum | <<locked>> | 84% | 58,189 psi | 87% | 2969 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,479 psi | 59% | 1982 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 84% | 56,724 psi | 85% | 3031 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 88% | 59,857 psi | 90% | 3081 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 90% | 57,740 psi | 87% | 2963 fps | 97.2% |
| SNPE Vectan SP 13 | <<locked>> | 98% | 58,436 psi | 88% | 3012 fps | 99.5% |
| Vihtavuori 20N29ᴾ | <<locked>> | 100% | 55,796 psi | 84% | 2989 fps | 98.2% |
| Vihtavuori 24N41 | <<locked>> | 94% | 57,740 psi | 87% | 3015 fps | 96.7% |
| Vihtavuori N165 | <<locked>> | 84% | 59,698 psi | 89% | 2943 fps | 100% |
| Vihtavuori N170 | <<locked>> | 88% | 59,596 psi | 89% | 3002 fps | 99.3% |
| Vihtavuori N565 | <<locked>> | 84% | 57,130 psi | 86% | 2995 fps | 100% |
| Vihtavuori N568 | <<locked>> | 88% | 59,988 psi | 90% | 3081 fps | 100% |
| Vihtavuori N570 | <<locked>> | 88% | 57,798 psi | 87% | 3097 fps | 99.6% |
| Winchester Supreme 780 | <<locked>> | 82% | 59,277 psi | 89% | 2956 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% | 55,419 psi | 83% | 2864 fps | 100% |
| Accurate 8700 | <<locked>> | 88% | 39,581 psi | 59% | 2684 fps | 95.8% |
| ADI AR 2213 | <<locked>> | 80% | 55,187 psi | 83% | 2976 fps | 100% |
| ADI AR 2217 | <<locked>> | 80% | 41,974 psi | 63% | 2736 fps | 99.6% |
| ADI AR 2218 | 90.2 gr | 82% | 38,870 psi | 58% | 2753 fps | 96.2% |
| ADI AR 2225 | <<locked>> | 80% | 39,378 psi | 59% | 2710 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 55,854 psi | 84% | 2969 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 80% | 54,447 psi | 82% | 2867 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 48,646 psi | 73% | 2844 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 80% | 40,683 psi | 61% | 2746 fps | 96.6% |
| Alliant Reloder-50 | <<locked>> | 82% | 38,363 psi | 57% | 2684 fps | 95.2% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 51,343 psi | 77% | 2877 fps | 99.3% |
| Bofors RP15 | <<locked>> | 80% | 52,054 psi | 78% | 2910 fps | 100% |
| Bofors RP30 | <<locked>> | 80% | 45,571 psi | 68% | 2812 fps | 99.9% |
| Bofors RP5 | <<locked>> | 80% | 55,854 psi | 84% | 2969 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 45,788 psi | 69% | 2805 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 80% | 56,101 psi | 84% | 2946 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 80% | 48,530 psi | 73% | 2933 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,921 psi | 43% | 1736 fps | 100% |
| Hodgdon US 869 | <<locked>> | 94% | 53,476 psi | 80% | 2940 fps | 95.8% |
| IMR 7828 SSC | <<locked>> | 80% | 54,012 psi | 81% | 2963 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 80% | 45,847 psi | 69% | 2723 fps | 95.3% |
| IMR 8133 Enduron | <<locked>> | 80% | 36,753 psi | 55% | 2635 fps | 98.5% |
| Lovex D100 | <<locked>> | 86% | 50,053 psi | 75% | 2831 fps | 95.4% |
| Lovex S071 | <<locked>> | 80% | 47,921 psi | 72% | 2749 fps | 100% |
| Norma 217 | <<locked>> | 80% | 37,623 psi | 56% | 2664 fps | 99.8% |
| Ramshot Grand | <<locked>> | 80% | 55,550 psi | 83% | 2986 fps | 100% |
| Ramshot LRT | 98.9 gr | 90% | 52,228 psi | 78% | 2976 fps | 95.6% |
| Ramshot Magnum | <<locked>> | 80% | 50,183 psi | 75% | 2851 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,747 psi | 45% | 1775 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 48,602 psi | 73% | 2907 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 44,556 psi | 67% | 2818 fps | 99.2% |
| Shooters World 50 BMG | <<locked>> | 86% | 50,053 psi | 75% | 2831 fps | 95.4% |
| SNPE Vectan SP 13 | <<locked>> | 86% | 38,769 psi | 58% | 2641 fps | 95.1% |
| Vihtavuori 20N29 | <<locked>> | 94% | 45,020 psi | 67% | 2792 fps | 95.5% |
| Vihtavuori 24N41 | <<locked>> | 92% | 53,766 psi | 81% | 2949 fps | 95.8% |
| Vihtavuori N165 | <<locked>> | 80% | 52,489 psi | 79% | 2841 fps | 100% |
| Vihtavuori N170 | <<locked>> | 80% | 45,426 psi | 68% | 2756 fps | 96.7% |
| Vihtavuori N565 | <<locked>> | 80% | 49,995 psi | 75% | 2877 fps | 100% |
| Vihtavuori N568 | <<locked>> | 80% | 45,165 psi | 68% | 2825 fps | 99% |
| Vihtavuori N570 | 86.2 gr | 80% | 43,265 psi | 65% | 2822 fps | 97% |
| Winchester Supreme 780 | <<locked>> | 80% | 55,230 psi | 83% | 2897 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 42 powders for 7.21 Firebird loaded with the .285 | 173gr | Prvi Partizan FMJ BT. ADI AR 2218 delivers the highest muzzle velocity at 3,123 fps; across all powders the maximum-charge window runs from 1,936 fps to 3,123 fps. Hodgdon TrailBoss gives the best case fill at 100 %, and 42 of the 42 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 173.0 gr projectile in 0.285" calls for a 1:12.0 twist; slower twists will usually not stabilise this weight. Hodgdon TrailBoss, ReloadSwiss RS 14, Vihtavuori 20N29 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, Ramshot LRT rank at the top here: for 7.21 Firebird with the .285 | 173gr | Prvi Partizan FMJ BT 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.