Load Specifications
Load data in caliber 7.21 Firebird with .284 | 160gr | Prvi Partizan PSP BT bullet and 49 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 Alliant Reloder-50.
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>> | 84% | 59,886 psi | 90% | 3028 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 57,116 psi | 86% | 3097 fps | 99.2% |
| Accurate MAGPRO | <<locked>> | 82% | 59,393 psi | 89% | 3156 fps | 100% |
| ADI AR 2213 | <<locked>> | 84% | 59,843 psi | 90% | 3146 fps | 100% |
| ADI AR 2217 | <<locked>> | 92% | 60,046 psi | 90% | 3136 fps | 100% |
| ADI AR 2218 | <<locked>> | 94% | 56,956 psi | 85% | 3219 fps | 99.7% |
| ADI AR 2225 | <<locked>> | 94% | 60,249 psi | 90% | 3156 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 82% | 60,075 psi | 90% | 3107 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 82% | 56,478 psi | 85% | 3081 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 84% | 58,740 psi | 88% | 3031 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 88% | 60,046 psi | 90% | 3117 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 92% | 59,292 psi | 89% | 3189 fps | 99.6% |
| Alliant Reloder-50 | <<locked>> | 96% | 59,770 psi | 90% | 3189 fps | 99.4% |
| Baschieri & Pellagri 109 | <<locked>> | 86% | 59,480 psi | 89% | 3107 fps | 99.7% |
| Bofors RP15 | <<locked>> | 86% | 59,741 psi | 90% | 3130 fps | 100% |
| Bofors RP30 | <<locked>> | 90% | 59,843 psi | 90% | 3150 fps | 100% |
| Bofors RP5 | <<locked>> | 82% | 56,478 psi | 85% | 3081 fps | 100% |
| Hodgdon H1000 | <<locked>> | 88% | 57,290 psi | 86% | 3094 fps | 100% |
| Hodgdon H4831 | <<locked>> | 82% | 57,885 psi | 87% | 3071 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 82% | 56,942 psi | 85% | 3054 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 86% | 56,173 psi | 84% | 3163 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,189 psi | 57% | 2001 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 82% | 57,696 psi | 86% | 3045 fps | 100% |
| IMR 7828 SSC | <<locked>> | 84% | 58,523 psi | 88% | 3133 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 90% | 60,307 psi | 90% | 3064 fps | 97.7% |
| IMR 8133 Enduron | <<locked>> | 96% | 59,016 psi | 88% | 3150 fps | 100% |
| Lovex D100 | <<locked>> | 92% | 58,436 psi | 88% | 3061 fps | 96.6% |
| Lovex S071 | <<locked>> | 88% | 58,363 psi | 87% | 3009 fps | 100% |
| Norma 217 | <<locked>> | 94% | 56,884 psi | 85% | 3110 fps | 100% |
| Ramshot Grand | <<locked>> | 82% | 56,159 psi | 84% | 3097 fps | 100% |
| Ramshot Magnum | <<locked>> | 86% | 58,827 psi | 88% | 3077 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,320 psi | 59% | 2051 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 86% | 57,029 psi | 85% | 3143 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 90% | 60,307 psi | 90% | 3186 fps | 100% |
| Rottweil R 905 | <<locked>> | 82% | 60,031 psi | 90% | 3100 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 92% | 58,436 psi | 88% | 3061 fps | 96.6% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 58,653 psi | 88% | 3104 fps | 99.1% |
| SNPE Vectan Tubal 8000 | <<locked>> | 82% | 59,669 psi | 89% | 3100 fps | 100% |
| Somchem S385 | <<locked>> | 82% | 60,220 psi | 90% | 3068 fps | 100% |
| Vihtavuori 20N29ᴾ | <<locked>> | 100% | 51,909 psi | 78% | 3009 fps | 96.6% |
| Vihtavuori N165 | <<locked>> | 84% | 56,681 psi | 85% | 2999 fps | 100% |
| Vihtavuori N170 | <<locked>> | 88% | 56,362 psi | 84% | 3045 fps | 98.3% |
| Vihtavuori N555 | <<locked>> | 82% | 60,205 psi | 90% | 3061 fps | 100% |
| Vihtavuori N560 | <<locked>> | 82% | 60,002 psi | 90% | 3166 fps | 100% |
| Vihtavuori N565 | <<locked>> | 86% | 57,725 psi | 87% | 3100 fps | 100% |
| Vihtavuori N568 | <<locked>> | 90% | 60,365 psi | 90% | 3189 fps | 100% |
| Vihtavuori N570 | <<locked>> | 90% | 58,044 psi | 87% | 3199 fps | 99.3% |
| Winchester StaBALL HD | <<locked>> | 82% | 56,623 psi | 85% | 3074 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 84% | 60,176 psi | 90% | 3068 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% | 52,446 psi | 79% | 2920 fps | 100% |
| Accurate 8700 | <<locked>> | 92% | 42,482 psi | 64% | 2831 fps | 96% |
| Accurate MAGPRO | <<locked>> | 80% | 55,361 psi | 83% | 3094 fps | 99.9% |
| ADI AR 2213 | <<locked>> | 80% | 52,054 psi | 78% | 3025 fps | 100% |
| ADI AR 2217 | <<locked>> | 80% | 39,233 psi | 59% | 2766 fps | 98.7% |
| ADI AR 2218 | 92.4 gr | 84% | 39,102 psi | 59% | 2838 fps | 95.2% |
| ADI AR 2225 | <<locked>> | 80% | 36,680 psi | 55% | 2740 fps | 99.8% |
| Alliant Reloder-19 | <<locked>> | 80% | 56,246 psi | 84% | 3051 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 52,779 psi | 79% | 3018 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 80% | 51,430 psi | 77% | 2927 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 45,730 psi | 69% | 2894 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 82% | 40,756 psi | 61% | 2835 fps | 95.8% |
| Alliant Reloder-50 | 96 gr | 86% | 41,234 psi | 62% | 2831 fps | 95.3% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 48,921 psi | 73% | 2923 fps | 98.3% |
| Bofors RP15 | <<locked>> | 80% | 49,153 psi | 74% | 2956 fps | 100% |
| Bofors RP30 | <<locked>> | 80% | 42,685 psi | 64% | 2844 fps | 99.3% |
| Bofors RP5 | <<locked>> | 80% | 52,779 psi | 79% | 3018 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 42,815 psi | 64% | 2844 fps | 99.6% |
| Hodgdon H4831 | <<locked>> | 80% | 54,085 psi | 81% | 3009 fps | 99.9% |
| Hodgdon H4831 SC | <<locked>> | 80% | 53,229 psi | 80% | 2995 fps | 99.9% |
| Hodgdon Retumbo | <<locked>> | 80% | 45,179 psi | 68% | 2972 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,674 psi | 43% | 1795 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 54,230 psi | 81% | 2989 fps | 99.9% |
| IMR 7828 SSC | <<locked>> | 80% | 50,995 psi | 76% | 3012 fps | 99.9% |
| IMR 7977 Enduron | <<locked>> | 84% | 49,705 psi | 75% | 2884 fps | 95.5% |
| IMR 8133 Enduron | <<locked>> | 80% | 34,142 psi | 51% | 2657 fps | 96.9% |
| Lovex D100 | <<locked>> | 90% | 54,462 psi | 82% | 2995 fps | 95.6% |
| Lovex S071 | <<locked>> | 80% | 45,295 psi | 68% | 2799 fps | 100% |
| Norma 217 | <<locked>> | 80% | 34,911 psi | 52% | 2687 fps | 98.9% |
| Ramshot Grand | <<locked>> | 80% | 52,199 psi | 78% | 3031 fps | 100% |
| Ramshot Magnum | <<locked>> | 80% | 47,181 psi | 71% | 2894 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,602 psi | 44% | 1837 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 45,150 psi | 68% | 2946 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 41,394 psi | 62% | 2841 fps | 98% |
| Rottweil R 905 | <<locked>> | 80% | 56,289 psi | 84% | 3048 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 90% | 54,462 psi | 82% | 2995 fps | 95.6% |
| SNPE Vectan SP 13 | <<locked>> | 90% | 41,626 psi | 62% | 2789 fps | 95.2% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 55,941 psi | 84% | 3041 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 56,405 psi | 85% | 3009 fps | 100% |
| Vihtavuori 20N29 | <<locked>> | 98% | 48,385 psi | 73% | 2943 fps | 95.6% |
| Vihtavuori N165 | <<locked>> | 80% | 49,734 psi | 75% | 2890 fps | 100% |
| Vihtavuori N170 | <<locked>> | 80% | 42,989 psi | 64% | 2789 fps | 95% |
| Vihtavuori N555 | <<locked>> | 80% | 56,463 psi | 85% | 3005 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 55,898 psi | 84% | 3100 fps | 100% |
| Vihtavuori N565 | <<locked>> | 80% | 47,181 psi | 71% | 2920 fps | 99.5% |
| Vihtavuori N568 | <<locked>> | 80% | 42,134 psi | 63% | 2854 fps | 97.7% |
| Vihtavuori N570 | 86.2 gr | 80% | 40,350 psi | 60% | 2844 fps | 95.1% |
| Winchester StaBALL HD | <<locked>> | 80% | 52,605 psi | 79% | 3015 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 52,533 psi | 79% | 2949 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 49 powders for 7.21 Firebird loaded with the .284 | 160gr | Prvi Partizan PSP BT. ADI AR 2218 delivers the highest muzzle velocity at 3,219 fps; across all powders the maximum-charge window runs from 2,001 fps to 3,219 fps. Accurate 8700 gives the best case fill at 100 %, and 49 of the 49 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 160.0 gr projectile in 0.284" calls for a 1:11.5 twist; slower twists will usually not stabilise this weight. Accurate 8700, Hodgdon TrailBoss, ReloadSwiss RS 14 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, Alliant Reloder-50 rank at the top here: for 7.21 Firebird with the .284 | 160gr | 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.