Load Specifications
Load data in caliber 7.21 Firebird with .284 | 174gr | Prvi Partizan SP 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.
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Max Load - Barrel Length: 26"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 3100 | <<locked>> | 82% | 59,190 psi | 89% | 2910 fps | 100% |
| Accurate 8700 | <<locked>> | 98% | 57,014 psi | 85% | 2999 fps | 99.6% |
| ADI AR 2213 | <<locked>> | 82% | 59,059 psi | 89% | 3028 fps | 100% |
| ADI AR 2217 | <<locked>> | 90% | 59,567 psi | 89% | 3022 fps | 100% |
| ADI AR 2218 | <<locked>> | 92% | 56,681 psi | 85% | 3114 fps | 99.9% |
| ADI AR 2225 | <<locked>> | 92% | 60,176 psi | 90% | 3045 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 82% | 59,654 psi | 89% | 3018 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 82% | 57,972 psi | 87% | 2910 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 86% | 59,567 psi | 89% | 2999 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 90% | 58,755 psi | 88% | 3081 fps | 99.9% |
| Alliant Reloder-50 | <<locked>> | 94% | 59,654 psi | 89% | 3084 fps | 99.8% |
| Baschieri & Pellagri 109 | <<locked>> | 84% | 58,494 psi | 88% | 2989 fps | 99.9% |
| Bofors RP15 | <<locked>> | 84% | 59,190 psi | 89% | 3012 fps | 100% |
| Bofors RP30 | <<locked>> | 88% | 59,437 psi | 89% | 3035 fps | 100% |
| Bofors RP5 | <<locked>> | 82% | 59,654 psi | 89% | 3018 fps | 100% |
| Hodgdon H1000 | <<locked>> | 86% | 56,608 psi | 85% | 2976 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 82% | 59,930 psi | 90% | 2995 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 86% | 60,263 psi | 90% | 3107 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,392 psi | 58% | 1929 fps | 100% |
| Hodgdon US 869 | <<locked>> | 96% | 57,232 psi | 86% | 2999 fps | 96.7% |
| IMR 7828 SSC | <<locked>> | 82% | 57,798 psi | 87% | 3012 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 88% | 59,205 psi | 89% | 2953 fps | 98.3% |
| IMR 8133 Enduron | <<locked>> | 94% | 58,856 psi | 88% | 3041 fps | 100% |
| Lovex D100 | <<locked>> | 90% | 57,566 psi | 86% | 2953 fps | 97.2% |
| Lovex S071 | <<locked>> | 86% | 57,870 psi | 87% | 2894 fps | 100% |
| Norma 217 | <<locked>> | 92% | 56,855 psi | 85% | 3002 fps | 100% |
| Ramshot Grand | <<locked>> | 82% | 59,799 psi | 90% | 3041 fps | 100% |
| Ramshot LRT | <<locked>> | 94% | 60,147 psi | 90% | 3104 fps | 97.5% |
| Ramshot Magnum | <<locked>> | 84% | 58,146 psi | 87% | 2963 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,407 psi | 59% | 1972 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 84% | 56,695 psi | 85% | 3025 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 88% | 59,857 psi | 90% | 3074 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 90% | 57,566 psi | 86% | 2953 fps | 97.2% |
| SNPE Vectan SP 13 | <<locked>> | 98% | 58,305 psi | 87% | 3002 fps | 99.5% |
| Vihtavuori 20N29ᴾ | <<locked>> | 100% | 55,651 psi | 83% | 2979 fps | 98.2% |
| Vihtavuori 24N41 | <<locked>> | 94% | 57,769 psi | 87% | 3009 fps | 96.8% |
| Vihtavuori N165 | <<locked>> | 84% | 59,654 psi | 89% | 2936 fps | 100% |
| Vihtavuori N170 | <<locked>> | 88% | 59,582 psi | 89% | 2999 fps | 99.3% |
| Vihtavuori N565 | <<locked>> | 84% | 57,246 psi | 86% | 2989 fps | 100% |
| Vihtavuori N568 | <<locked>> | 88% | 59,930 psi | 90% | 3074 fps | 100% |
| Vihtavuori N570 | <<locked>> | 88% | 57,754 psi | 87% | 3091 fps | 99.7% |
| Winchester Supreme 780 | <<locked>> | 82% | 59,234 psi | 89% | 2946 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% | 55,332 psi | 83% | 2858 fps | 100% |
| Accurate 8700 | <<locked>> | 88% | 39,566 psi | 59% | 2677 fps | 95.9% |
| ADI AR 2213 | <<locked>> | 80% | 55,100 psi | 83% | 2966 fps | 100% |
| ADI AR 2217 | <<locked>> | 80% | 41,901 psi | 63% | 2726 fps | 99.6% |
| ADI AR 2218 | 89.9 gr | 82% | 38,943 psi | 58% | 2749 fps | 96.3% |
| ADI AR 2225 | <<locked>> | 80% | 39,305 psi | 59% | 2700 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 55,767 psi | 84% | 2959 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 80% | 54,346 psi | 81% | 2858 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 48,718 psi | 73% | 2838 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 80% | 40,625 psi | 61% | 2740 fps | 96.7% |
| Alliant Reloder-50 | <<locked>> | 82% | 38,363 psi | 57% | 2677 fps | 95.2% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 51,445 psi | 77% | 2874 fps | 99.3% |
| Bofors RP15 | <<locked>> | 80% | 51,953 psi | 78% | 2897 fps | 100% |
| Bofors RP30 | <<locked>> | 80% | 45,469 psi | 68% | 2802 fps | 99.9% |
| Bofors RP5 | <<locked>> | 80% | 55,767 psi | 84% | 2959 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 45,716 psi | 69% | 2799 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 80% | 55,999 psi | 84% | 2936 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 80% | 48,472 psi | 73% | 2927 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,819 psi | 43% | 1726 fps | 100% |
| Hodgdon US 869 | <<locked>> | 94% | 53,345 psi | 80% | 2933 fps | 95.8% |
| IMR 7828 SSC | <<locked>> | 80% | 54,099 psi | 81% | 2956 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 80% | 45,774 psi | 69% | 2717 fps | 95.3% |
| IMR 8133 Enduron | <<locked>> | 80% | 36,680 psi | 55% | 2628 fps | 98.5% |
| Lovex D100 | <<locked>> | 86% | 50,009 psi | 75% | 2825 fps | 95.5% |
| Lovex S071 | <<locked>> | 80% | 47,805 psi | 72% | 2743 fps | 100% |
| Norma 217 | <<locked>> | 80% | 37,536 psi | 56% | 2654 fps | 99.8% |
| Ramshot Grand | <<locked>> | 80% | 55,666 psi | 83% | 2979 fps | 100% |
| Ramshot LRT | 98.4 gr | 90% | 52,083 psi | 78% | 2966 fps | 95.6% |
| Ramshot Magnum | <<locked>> | 80% | 50,285 psi | 75% | 2844 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,776 psi | 45% | 1768 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 48,689 psi | 73% | 2900 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 44,483 psi | 67% | 2812 fps | 99.3% |
| Shooters World 50 BMG | <<locked>> | 86% | 50,009 psi | 75% | 2825 fps | 95.5% |
| SNPE Vectan SP 13 | <<locked>> | 86% | 38,725 psi | 58% | 2635 fps | 95.1% |
| Vihtavuori 20N29 | <<locked>> | 94% | 45,049 psi | 68% | 2789 fps | 95.6% |
| Vihtavuori 24N41 | <<locked>> | 92% | 53,766 psi | 81% | 2943 fps | 95.8% |
| Vihtavuori N165 | <<locked>> | 80% | 52,402 psi | 79% | 2831 fps | 100% |
| Vihtavuori N170 | <<locked>> | 80% | 45,498 psi | 68% | 2749 fps | 96.8% |
| Vihtavuori N565 | <<locked>> | 80% | 49,908 psi | 75% | 2871 fps | 100% |
| Vihtavuori N568 | <<locked>> | 80% | 45,107 psi | 68% | 2818 fps | 99% |
| Vihtavuori N570 | 85.9 gr | 80% | 43,352 psi | 65% | 2818 fps | 97.1% |
| Winchester Supreme 780 | <<locked>> | 80% | 55,317 psi | 83% | 2890 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 .284 | 174gr | Prvi Partizan SP. ADI AR 2218 delivers the highest muzzle velocity at 3,114 fps; across all powders the maximum-charge window runs from 1,929 fps to 3,114 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 58–90 %, leaving at least 10 % headroom. The 174.0 gr projectile in 0.284" calls for a 1:11.5 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 .284 | 174gr | Prvi Partizan SP 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.