Load Specifications
Load data in caliber 7.21 Firebird with .284 | 175gr | Swift A-Frame 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% | 58,697 psi | 88% | 2897 fps | 100% |
| Accurate 8700 | <<locked>> | 98% | 56,391 psi | 85% | 2982 fps | 99.5% |
| ADI AR 2213 | <<locked>> | 82% | 58,552 psi | 88% | 3012 fps | 100% |
| ADI AR 2217 | <<locked>> | 90% | 58,914 psi | 88% | 3005 fps | 100% |
| ADI AR 2218 | <<locked>> | 92% | 56,144 psi | 84% | 3097 fps | 99.9% |
| ADI AR 2225 | <<locked>> | 92% | 59,553 psi | 89% | 3031 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 82% | 59,132 psi | 89% | 3005 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 82% | 57,609 psi | 86% | 2897 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 86% | 59,088 psi | 89% | 2986 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 90% | 58,233 psi | 87% | 3068 fps | 99.8% |
| Alliant Reloder-50 | <<locked>> | 94% | 58,987 psi | 88% | 3071 fps | 99.7% |
| Baschieri & Pellagri 109 | <<locked>> | 84% | 58,189 psi | 87% | 2976 fps | 99.9% |
| Bofors RP15 | <<locked>> | 84% | 58,726 psi | 88% | 2995 fps | 100% |
| Bofors RP30 | <<locked>> | 88% | 59,001 psi | 88% | 3022 fps | 100% |
| Bofors RP5 | <<locked>> | 82% | 59,132 psi | 89% | 3005 fps | 100% |
| Hodgdon H1000 | <<locked>> | 88% | 60,336 psi | 90% | 3022 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 82% | 59,451 psi | 89% | 2982 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 86% | 59,509 psi | 89% | 3091 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,377 psi | 58% | 1923 fps | 100% |
| Hodgdon US 869 | <<locked>> | 96% | 56,681 psi | 85% | 2982 fps | 96.6% |
| IMR 4955 Enduron | <<locked>> | 82% | 59,915 psi | 90% | 2966 fps | 100% |
| IMR 7828 SSC | <<locked>> | 82% | 57,508 psi | 86% | 3002 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 88% | 58,813 psi | 88% | 2940 fps | 98.2% |
| IMR 8133 Enduron | <<locked>> | 94% | 58,247 psi | 87% | 3025 fps | 100% |
| Lovex D100 | <<locked>> | 90% | 57,130 psi | 86% | 2940 fps | 97.1% |
| Lovex S071 | <<locked>> | 86% | 57,392 psi | 86% | 2881 fps | 100% |
| Norma 217 | <<locked>> | 94% | 60,133 psi | 90% | 3041 fps | 100% |
| Ramshot Grand | <<locked>> | 82% | 59,277 psi | 89% | 3025 fps | 100% |
| Ramshot LRT | <<locked>> | 94% | 59,480 psi | 89% | 3087 fps | 97.3% |
| Ramshot Magnum | <<locked>> | 84% | 57,725 psi | 87% | 2946 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,392 psi | 59% | 1965 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 84% | 56,028 psi | 84% | 3009 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 88% | 59,277 psi | 89% | 3058 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 90% | 57,130 psi | 86% | 2940 fps | 97.1% |
| SNPE Vectan SP 13 | <<locked>> | 98% | 57,682 psi | 86% | 2986 fps | 99.4% |
| Vihtavuori 20N29ᴾ | <<locked>> | 100% | 55,100 psi | 83% | 2963 fps | 98.1% |
| Vihtavuori 24N41 | <<locked>> | 94% | 57,174 psi | 86% | 2992 fps | 96.6% |
| Vihtavuori N165 | <<locked>> | 84% | 59,205 psi | 89% | 2923 fps | 100% |
| Vihtavuori N170 | <<locked>> | 88% | 59,059 psi | 89% | 2982 fps | 99.2% |
| Vihtavuori N565 | <<locked>> | 84% | 56,623 psi | 85% | 2972 fps | 100% |
| Vihtavuori N568 | <<locked>> | 88% | 59,393 psi | 89% | 3061 fps | 100% |
| Vihtavuori N570 | <<locked>> | 88% | 57,174 psi | 86% | 3071 fps | 99.6% |
| Winchester StaBALL HD | <<locked>> | 82% | 60,060 psi | 90% | 2999 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 82% | 58,769 psi | 88% | 2933 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% | 54,998 psi | 82% | 2844 fps | 100% |
| Accurate 8700 | <<locked>> | 88% | 39,088 psi | 59% | 2664 fps | 95.7% |
| ADI AR 2213 | <<locked>> | 80% | 54,563 psi | 82% | 2953 fps | 100% |
| ADI AR 2217 | <<locked>> | 80% | 41,582 psi | 62% | 2713 fps | 99.6% |
| ADI AR 2218 | 88.8 gr | 82% | 38,464 psi | 58% | 2733 fps | 96.1% |
| ADI AR 2225 | <<locked>> | 80% | 38,957 psi | 58% | 2690 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 55,245 psi | 83% | 2946 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 80% | 53,998 psi | 81% | 2848 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 48,196 psi | 72% | 2822 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 80% | 40,219 psi | 60% | 2726 fps | 96.6% |
| Alliant Reloder-50 | <<locked>> | 82% | 37,985 psi | 57% | 2664 fps | 95.1% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 51,068 psi | 77% | 2861 fps | 99.2% |
| Bofors RP15 | <<locked>> | 80% | 51,605 psi | 77% | 2887 fps | 100% |
| Bofors RP30 | <<locked>> | 80% | 45,150 psi | 68% | 2792 fps | 99.9% |
| Bofors RP5 | <<locked>> | 80% | 55,245 psi | 83% | 2946 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 45,397 psi | 68% | 2785 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 80% | 55,521 psi | 83% | 2923 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 80% | 48,051 psi | 72% | 2913 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,819 psi | 43% | 1719 fps | 100% |
| Hodgdon US 869 | <<locked>> | 94% | 52,765 psi | 79% | 2917 fps | 95.6% |
| IMR 4955 Enduron | <<locked>> | 80% | 56,318 psi | 84% | 2910 fps | 100% |
| IMR 7828 SSC | <<locked>> | 80% | 53,563 psi | 80% | 2940 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 80% | 45,527 psi | 68% | 2703 fps | 95.2% |
| IMR 8133 Enduron | <<locked>> | 80% | 36,332 psi | 54% | 2615 fps | 98.4% |
| Lovex D100 | <<locked>> | 86% | 49,588 psi | 74% | 2812 fps | 95.3% |
| Lovex S071 | <<locked>> | 80% | 47,427 psi | 71% | 2730 fps | 100% |
| Norma 217 | <<locked>> | 80% | 37,173 psi | 56% | 2641 fps | 99.8% |
| Ramshot Grand | <<locked>> | 80% | 55,114 psi | 83% | 2963 fps | 100% |
| Ramshot LRT | 97.3 gr | 90% | 51,619 psi | 77% | 2953 fps | 95.5% |
| Ramshot Magnum | <<locked>> | 80% | 49,821 psi | 75% | 2831 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,660 psi | 44% | 1759 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 48,051 psi | 72% | 2887 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 44,092 psi | 66% | 2795 fps | 99.2% |
| Shooters World 50 BMG | <<locked>> | 86% | 49,588 psi | 74% | 2812 fps | 95.3% |
| SNPE Vectan SP 13 | <<locked>> | 86% | 38,377 psi | 58% | 2621 fps | 95% |
| Vihtavuori 20N29 | <<locked>> | 94% | 44,614 psi | 67% | 2772 fps | 95.4% |
| Vihtavuori 24N41 | <<locked>> | 92% | 53,156 psi | 80% | 2927 fps | 95.7% |
| Vihtavuori N165 | <<locked>> | 80% | 52,098 psi | 78% | 2818 fps | 100% |
| Vihtavuori N170 | <<locked>> | 80% | 45,107 psi | 68% | 2736 fps | 96.7% |
| Vihtavuori N565 | <<locked>> | 80% | 49,603 psi | 74% | 2858 fps | 100% |
| Vihtavuori N568 | <<locked>> | 80% | 44,657 psi | 67% | 2805 fps | 99% |
| Vihtavuori N570 | 84.9 gr | 80% | 42,888 psi | 64% | 2802 fps | 97% |
| Winchester StaBALL HD | <<locked>> | 80% | 55,869 psi | 84% | 2943 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 54,868 psi | 82% | 2877 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 | 175gr | Swift A-Frame. ADI AR 2218 delivers the highest muzzle velocity at 3,097 fps; across all powders the maximum-charge window runs from 1,923 fps to 3,097 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 58–90 %, leaving at least 10 % headroom. The 175.0 gr projectile in 0.284" calls for a 1:10.5 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 | 175gr | Swift A-Frame 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.