Load Specifications
Load data in caliber 7.21 Firebird with .284 | 174gr | Prvi Partizan PSP BT bullet and 44 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% | 58,653 psi | 88% | 2904 fps | 100% |
| Accurate 8700 | <<locked>> | 98% | 56,391 psi | 85% | 2989 fps | 99.5% |
| ADI AR 2213 | <<locked>> | 82% | 58,479 psi | 88% | 3022 fps | 100% |
| ADI AR 2217 | <<locked>> | 90% | 59,016 psi | 88% | 3015 fps | 100% |
| ADI AR 2218 | <<locked>> | 92% | 56,188 psi | 84% | 3107 fps | 99.9% |
| ADI AR 2225 | <<locked>> | 92% | 59,422 psi | 89% | 3035 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 82% | 59,074 psi | 89% | 3012 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 82% | 57,551 psi | 86% | 2907 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 86% | 59,001 psi | 88% | 2992 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 90% | 58,276 psi | 87% | 3074 fps | 99.8% |
| Alliant Reloder-50 | <<locked>> | 94% | 59,030 psi | 88% | 3077 fps | 99.7% |
| Baschieri & Pellagri 109 | <<locked>> | 84% | 58,102 psi | 87% | 2982 fps | 99.8% |
| Bofors RP15 | <<locked>> | 84% | 58,668 psi | 88% | 3002 fps | 100% |
| Bofors RP30 | <<locked>> | 88% | 58,929 psi | 88% | 3025 fps | 100% |
| Bofors RP5 | <<locked>> | 82% | 59,074 psi | 89% | 3012 fps | 100% |
| Hodgdon H1000 | <<locked>> | 88% | 60,234 psi | 90% | 3025 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 82% | 59,408 psi | 89% | 2989 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 86% | 59,611 psi | 89% | 3100 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,319 psi | 57% | 1926 fps | 100% |
| Hodgdon US 869 | <<locked>> | 96% | 56,681 psi | 85% | 2989 fps | 96.6% |
| IMR 4955 Enduron | <<locked>> | 82% | 60,046 psi | 90% | 2976 fps | 100% |
| IMR 7828 SSC | <<locked>> | 82% | 57,421 psi | 86% | 3009 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 88% | 58,929 psi | 88% | 2946 fps | 98.2% |
| IMR 8133 Enduron | <<locked>> | 94% | 58,305 psi | 87% | 3031 fps | 100% |
| Lovex D100 | <<locked>> | 90% | 57,174 psi | 86% | 2946 fps | 97.1% |
| Lovex S071 | <<locked>> | 86% | 57,319 psi | 86% | 2887 fps | 100% |
| Norma 217 | <<locked>> | 94% | 60,191 psi | 90% | 3051 fps | 100% |
| Ramshot Grand | <<locked>> | 82% | 59,219 psi | 89% | 3031 fps | 100% |
| Ramshot LRT | <<locked>> | 94% | 59,509 psi | 89% | 3094 fps | 97.3% |
| Ramshot Magnum | <<locked>> | 84% | 57,609 psi | 86% | 2953 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,479 psi | 59% | 1972 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 84% | 56,115 psi | 84% | 3018 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 88% | 59,350 psi | 89% | 3064 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 90% | 57,174 psi | 86% | 2946 fps | 97.1% |
| SNPE Vectan SP 13 | <<locked>> | 98% | 57,696 psi | 86% | 2992 fps | 99.4% |
| Vihtavuori 20N29ᴾ | <<locked>> | 100% | 55,100 psi | 83% | 2969 fps | 98% |
| Vihtavuori 24N41 | <<locked>> | 94% | 57,203 psi | 86% | 2999 fps | 96.6% |
| Vihtavuori N165 | <<locked>> | 84% | 59,335 psi | 89% | 2933 fps | 100% |
| Vihtavuori N170 | <<locked>> | 88% | 59,117 psi | 89% | 2989 fps | 99.2% |
| Vihtavuori N565 | <<locked>> | 84% | 56,710 psi | 85% | 2982 fps | 100% |
| Vihtavuori N568 | <<locked>> | 88% | 59,234 psi | 89% | 3064 fps | 100% |
| Vihtavuori N570 | <<locked>> | 88% | 57,246 psi | 86% | 3081 fps | 99.6% |
| Winchester StaBALL HD | <<locked>> | 82% | 59,973 psi | 90% | 3005 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 82% | 58,697 psi | 88% | 2940 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% | 54,984 psi | 82% | 2854 fps | 100% |
| Accurate 8700 | <<locked>> | 88% | 39,131 psi | 59% | 2667 fps | 95.7% |
| ADI AR 2213 | <<locked>> | 80% | 54,708 psi | 82% | 2963 fps | 100% |
| ADI AR 2217 | <<locked>> | 80% | 41,539 psi | 62% | 2720 fps | 99.6% |
| ADI AR 2218 | 89.2 gr | 82% | 38,551 psi | 58% | 2743 fps | 96.1% |
| ADI AR 2225 | <<locked>> | 80% | 38,943 psi | 58% | 2697 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 55,390 psi | 83% | 2956 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 80% | 53,954 psi | 81% | 2854 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 48,167 psi | 72% | 2831 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 80% | 40,176 psi | 60% | 2730 fps | 96.5% |
| Alliant Reloder-50 | <<locked>> | 82% | 37,927 psi | 57% | 2667 fps | 95% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 51,024 psi | 76% | 2867 fps | 99.2% |
| Bofors RP15 | <<locked>> | 80% | 51,561 psi | 77% | 2894 fps | 100% |
| Bofors RP30 | <<locked>> | 80% | 45,121 psi | 68% | 2799 fps | 99.9% |
| Bofors RP5 | <<locked>> | 80% | 55,390 psi | 83% | 2956 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 45,368 psi | 68% | 2795 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 80% | 55,680 psi | 83% | 2933 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 80% | 48,008 psi | 72% | 2917 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,819 psi | 43% | 1726 fps | 100% |
| Hodgdon US 869 | <<locked>> | 94% | 52,779 psi | 79% | 2923 fps | 95.6% |
| IMR 4955 Enduron | <<locked>> | 80% | 56,275 psi | 84% | 2920 fps | 100% |
| IMR 7828 SSC | <<locked>> | 80% | 53,505 psi | 80% | 2946 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 80% | 45,498 psi | 68% | 2710 fps | 95.2% |
| IMR 8133 Enduron | <<locked>> | 80% | 36,303 psi | 54% | 2621 fps | 98.4% |
| Lovex D100 | <<locked>> | 86% | 49,632 psi | 74% | 2822 fps | 95.3% |
| Lovex S071 | <<locked>> | 80% | 47,427 psi | 71% | 2733 fps | 100% |
| Norma 217 | <<locked>> | 80% | 37,173 psi | 56% | 2648 fps | 99.8% |
| Ramshot Grand | <<locked>> | 80% | 55,071 psi | 83% | 2969 fps | 100% |
| Ramshot LRT | 97.7 gr | 90% | 51,634 psi | 77% | 2959 fps | 95.4% |
| Ramshot Magnum | <<locked>> | 80% | 49,777 psi | 75% | 2838 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,776 psi | 45% | 1768 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 48,138 psi | 72% | 2894 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 44,019 psi | 66% | 2802 fps | 99.2% |
| Shooters World 50 BMG | <<locked>> | 86% | 49,632 psi | 74% | 2822 fps | 95.3% |
| SNPE Vectan SP 13 | <<locked>> | 88% | 41,075 psi | 62% | 2690 fps | 96% |
| Vihtavuori 20N29 | <<locked>> | 94% | 44,498 psi | 67% | 2776 fps | 95.4% |
| Vihtavuori 24N41 | <<locked>> | 92% | 53,200 psi | 80% | 2933 fps | 95.7% |
| Vihtavuori N165 | <<locked>> | 80% | 52,054 psi | 78% | 2825 fps | 100% |
| Vihtavuori N170 | <<locked>> | 80% | 45,078 psi | 68% | 2743 fps | 96.6% |
| Vihtavuori N565 | <<locked>> | 80% | 49,574 psi | 74% | 2864 fps | 99.9% |
| Vihtavuori N568 | <<locked>> | 80% | 44,744 psi | 67% | 2812 fps | 99% |
| Vihtavuori N570 | 85.2 gr | 80% | 42,830 psi | 64% | 2805 fps | 96.9% |
| Winchester StaBALL HD | <<locked>> | 80% | 55,767 psi | 84% | 2949 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 54,810 psi | 82% | 2884 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 44 powders for 7.21 Firebird loaded with the .284 | 174gr | Prvi Partizan PSP BT. ADI AR 2218 delivers the highest muzzle velocity at 3,107 fps; across all powders the maximum-charge window runs from 1,926 fps to 3,107 fps. Hodgdon TrailBoss gives the best case fill at 100 %, and 44 of the 44 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 174.0 gr projectile in 0.284" calls for a 1:11.0 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 .284 | 174gr | Prvi Partizan PSP 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.