Load Specifications
Load data in caliber 7.21 Firebird with .285 | 173gr | 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% | 59,393 psi | 89% | 2920 fps | 100% |
| Accurate 8700 | <<locked>> | 98% | 57,537 psi | 86% | 3012 fps | 99.6% |
| ADI AR 2213 | <<locked>> | 82% | 59,466 psi | 89% | 3041 fps | 100% |
| ADI AR 2217 | <<locked>> | 90% | 59,872 psi | 90% | 3031 fps | 100% |
| ADI AR 2218 | <<locked>> | 92% | 57,305 psi | 86% | 3130 fps | 99.9% |
| ADI AR 2225 | <<locked>> | 90% | 56,652 psi | 85% | 3002 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 82% | 60,002 psi | 90% | 3031 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 82% | 58,378 psi | 88% | 2920 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 86% | 59,959 psi | 90% | 3012 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 90% | 59,364 psi | 89% | 3094 fps | 99.9% |
| Alliant Reloder-50 | <<locked>> | 94% | 60,234 psi | 90% | 3100 fps | 99.8% |
| Baschieri & Pellagri 109 | <<locked>> | 84% | 58,943 psi | 88% | 3002 fps | 99.9% |
| Bofors RP15 | <<locked>> | 84% | 59,582 psi | 89% | 3022 fps | 100% |
| Bofors RP30 | <<locked>> | 88% | 59,988 psi | 90% | 3048 fps | 100% |
| Bofors RP5 | <<locked>> | 82% | 60,002 psi | 90% | 3031 fps | 100% |
| Hodgdon H1000 | <<locked>> | 86% | 57,159 psi | 86% | 2992 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 82% | 60,307 psi | 90% | 3009 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 84% | 56,521 psi | 85% | 3061 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,305 psi | 57% | 1936 fps | 100% |
| Hodgdon US 869 | <<locked>> | 96% | 57,711 psi | 87% | 3012 fps | 96.8% |
| IMR 7828 SSC | <<locked>> | 82% | 58,233 psi | 87% | 3028 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 88% | 59,654 psi | 89% | 2969 fps | 98.3% |
| IMR 8133 Enduron | <<locked>> | 94% | 59,364 psi | 89% | 3051 fps | 100% |
| Lovex D100 | <<locked>> | 90% | 58,088 psi | 87% | 2969 fps | 97.3% |
| Lovex S071 | <<locked>> | 86% | 58,102 psi | 87% | 2904 fps | 100% |
| Norma 217 | <<locked>> | 92% | 57,392 psi | 86% | 3015 fps | 100% |
| Ramshot Grand | <<locked>> | 82% | 60,205 psi | 90% | 3051 fps | 100% |
| Ramshot LRT | <<locked>> | 92% | 56,507 psi | 85% | 3051 fps | 96.7% |
| Ramshot Magnum | <<locked>> | 84% | 58,682 psi | 88% | 2976 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,465 psi | 59% | 1982 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 84% | 57,246 psi | 86% | 3038 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 88% | 60,307 psi | 90% | 3084 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 90% | 58,088 psi | 87% | 2969 fps | 97.3% |
| SNPE Vectan SP 13 | <<locked>> | 98% | 58,827 psi | 88% | 3015 fps | 99.5% |
| Vihtavuori 20N29ᴾ | <<locked>> | 100% | 56,318 psi | 84% | 2995 fps | 98.3% |
| Vihtavuori 24N41 | <<locked>> | 94% | 58,117 psi | 87% | 3022 fps | 96.8% |
| Vihtavuori N165 | <<locked>> | 84% | 60,002 psi | 90% | 2949 fps | 100% |
| Vihtavuori N170 | <<locked>> | 88% | 60,002 psi | 90% | 3009 fps | 99.3% |
| Vihtavuori N565 | <<locked>> | 84% | 57,624 psi | 86% | 3002 fps | 100% |
| Vihtavuori N568 | <<locked>> | 86% | 56,318 psi | 84% | 3025 fps | 100% |
| Vihtavuori N570 | <<locked>> | 88% | 58,276 psi | 87% | 3104 fps | 99.7% |
| Winchester Supreme 780 | <<locked>> | 82% | 59,582 psi | 89% | 2959 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% | 55,724 psi | 84% | 2871 fps | 100% |
| Accurate 8700 | <<locked>> | 88% | 39,958 psi | 60% | 2690 fps | 96% |
| ADI AR 2213 | <<locked>> | 80% | 55,492 psi | 83% | 2982 fps | 100% |
| ADI AR 2217 | <<locked>> | 80% | 42,279 psi | 63% | 2740 fps | 99.7% |
| ADI AR 2218 | 88.6 gr | 80% | 36,448 psi | 55% | 2690 fps | 95.1% |
| ADI AR 2225 | <<locked>> | 80% | 39,697 psi | 60% | 2717 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 56,159 psi | 84% | 2972 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 80% | 54,795 psi | 82% | 2874 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 48,979 psi | 73% | 2848 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 80% | 40,930 psi | 61% | 2753 fps | 96.8% |
| Alliant Reloder-50 | <<locked>> | 82% | 38,783 psi | 58% | 2690 fps | 95.4% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 51,735 psi | 78% | 2884 fps | 99.3% |
| Bofors RP15 | <<locked>> | 80% | 52,359 psi | 78% | 2913 fps | 100% |
| Bofors RP30 | <<locked>> | 80% | 45,876 psi | 69% | 2818 fps | 99.9% |
| Bofors RP5 | <<locked>> | 80% | 56,159 psi | 84% | 2972 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 46,137 psi | 69% | 2812 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 80% | 56,405 psi | 85% | 2953 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 80% | 48,921 psi | 73% | 2940 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,834 psi | 43% | 1736 fps | 100% |
| Hodgdon US 869 | <<locked>> | 94% | 53,824 psi | 81% | 2946 fps | 95.9% |
| IMR 7828 SSC | <<locked>> | 80% | 54,331 psi | 81% | 2966 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 80% | 46,093 psi | 69% | 2730 fps | 95.4% |
| IMR 8133 Enduron | <<locked>> | 80% | 37,043 psi | 56% | 2641 fps | 98.6% |
| Lovex D100 | <<locked>> | 86% | 50,372 psi | 76% | 2838 fps | 95.5% |
| Lovex S071 | <<locked>> | 80% | 48,095 psi | 72% | 2753 fps | 100% |
| Norma 217 | <<locked>> | 80% | 37,942 psi | 57% | 2667 fps | 99.8% |
| Ramshot Grand | <<locked>> | 80% | 56,072 psi | 84% | 2992 fps | 100% |
| Ramshot LRT | 99.5 gr | 90% | 52,649 psi | 79% | 2982 fps | 95.7% |
| Ramshot Magnum | <<locked>> | 80% | 50,647 psi | 76% | 2858 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,791 psi | 45% | 1778 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 49,095 psi | 74% | 2913 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 44,831 psi | 67% | 2822 fps | 99.3% |
| Shooters World 50 BMG | <<locked>> | 86% | 50,372 psi | 76% | 2838 fps | 95.5% |
| SNPE Vectan SP 13 | <<locked>> | 86% | 39,001 psi | 58% | 2648 fps | 95.2% |
| Vihtavuori 20N29 | <<locked>> | 94% | 45,527 psi | 68% | 2802 fps | 95.7% |
| Vihtavuori 24N41 | <<locked>> | 92% | 54,128 psi | 81% | 2953 fps | 95.9% |
| Vihtavuori N165 | <<locked>> | 80% | 52,779 psi | 79% | 2844 fps | 100% |
| Vihtavuori N170 | <<locked>> | 80% | 45,803 psi | 69% | 2762 fps | 96.9% |
| Vihtavuori N565 | <<locked>> | 80% | 50,299 psi | 75% | 2884 fps | 100% |
| Vihtavuori N568 | <<locked>> | 80% | 45,455 psi | 68% | 2831 fps | 99.1% |
| Vihtavuori N570 | 86.8 gr | 80% | 43,714 psi | 66% | 2831 fps | 97.2% |
| Winchester Supreme 780 | <<locked>> | 80% | 55,695 psi | 83% | 2904 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 SP. ADI AR 2218 delivers the highest muzzle velocity at 3,130 fps; across all powders the maximum-charge window runs from 1,936 fps to 3,130 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 1:12.5 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 .285 | 173gr | 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.