Load Specifications
Load data in caliber 7.21 Firebird with .284 | 180gr | Sierra MatchKing 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% | 59,306 psi | 89% | 2871 fps | 100% |
| Accurate 8700 | <<locked>> | 98% | 57,087 psi | 86% | 2963 fps | 99.7% |
| ADI AR 2213 | <<locked>> | 82% | 59,234 psi | 89% | 2986 fps | 100% |
| ADI AR 2217 | <<locked>> | 90% | 59,785 psi | 90% | 2982 fps | 100% |
| ADI AR 2218 | <<locked>> | 92% | 56,826 psi | 85% | 3077 fps | 100% |
| ADI AR 2225 | <<locked>> | 92% | 60,321 psi | 90% | 3005 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 82% | 59,799 psi | 90% | 2976 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 82% | 58,204 psi | 87% | 2867 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 86% | 59,828 psi | 90% | 2959 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 90% | 59,074 psi | 89% | 3045 fps | 99.9% |
| Alliant Reloder-50 | <<locked>> | 94% | 59,785 psi | 90% | 3051 fps | 99.8% |
| Baschieri & Pellagri 109 | <<locked>> | 84% | 58,682 psi | 88% | 2949 fps | 99.9% |
| Bofors RP15 | <<locked>> | 84% | 59,393 psi | 89% | 2972 fps | 100% |
| Bofors RP30 | <<locked>> | 88% | 59,640 psi | 89% | 2995 fps | 100% |
| Bofors RP5 | <<locked>> | 82% | 59,799 psi | 90% | 2976 fps | 100% |
| Hodgdon H1000 | <<locked>> | 86% | 56,942 psi | 85% | 2936 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 82% | 60,075 psi | 90% | 2956 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 84% | 56,318 psi | 84% | 3009 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,392 psi | 58% | 1893 fps | 100% |
| Hodgdon US 869 | <<locked>> | 96% | 57,305 psi | 86% | 2963 fps | 97% |
| IMR 7828 SSC | <<locked>> | 82% | 58,189 psi | 87% | 2976 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 88% | 59,480 psi | 89% | 2917 fps | 98.5% |
| IMR 8133 Enduron | <<locked>> | 94% | 58,972 psi | 88% | 2999 fps | 100% |
| Lovex D100 | <<locked>> | 90% | 57,827 psi | 87% | 2920 fps | 97.5% |
| Lovex S071 | <<locked>> | 86% | 57,986 psi | 87% | 2851 fps | 100% |
| Norma 217 | <<locked>> | 92% | 57,159 psi | 86% | 2966 fps | 100% |
| Ramshot Grand | <<locked>> | 82% | 60,075 psi | 90% | 3002 fps | 100% |
| Ramshot LRT | <<locked>> | 94% | 60,365 psi | 90% | 3071 fps | 97.8% |
| Ramshot Magnum | <<locked>> | 84% | 58,334 psi | 87% | 2923 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,421 psi | 59% | 1936 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 84% | 56,956 psi | 85% | 2989 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 88% | 60,089 psi | 90% | 3035 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 90% | 57,827 psi | 87% | 2920 fps | 97.5% |
| SNPE Vectan SP 13 | <<locked>> | 98% | 58,523 psi | 88% | 2966 fps | 99.6% |
| Vihtavuori 20N29ᴾ | <<locked>> | 100% | 55,840 psi | 84% | 2946 fps | 98.4% |
| Vihtavuori 24N41 | <<locked>> | 94% | 57,740 psi | 87% | 2969 fps | 97% |
| Vihtavuori N165 | <<locked>> | 84% | 59,857 psi | 90% | 2897 fps | 100% |
| Vihtavuori N170 | <<locked>> | 88% | 59,669 psi | 89% | 2956 fps | 99.4% |
| Vihtavuori N565 | <<locked>> | 84% | 57,363 psi | 86% | 2949 fps | 100% |
| Vihtavuori N568 | <<locked>> | 88% | 60,104 psi | 90% | 3035 fps | 100% |
| Vihtavuori N570 | <<locked>> | 88% | 57,885 psi | 87% | 3051 fps | 99.8% |
| Winchester Supreme 780 | <<locked>> | 82% | 59,422 psi | 89% | 2907 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% | 55,593 psi | 83% | 2822 fps | 100% |
| Accurate 8700 | <<locked>> | 86% | 36,840 psi | 55% | 2582 fps | 95.2% |
| ADI AR 2213 | <<locked>> | 80% | 55,376 psi | 83% | 2930 fps | 100% |
| ADI AR 2217 | <<locked>> | 80% | 42,090 psi | 63% | 2694 fps | 99.8% |
| ADI AR 2218 | 85.9 gr | 80% | 36,201 psi | 54% | 2644 fps | 95.4% |
| ADI AR 2225 | <<locked>> | 80% | 39,552 psi | 59% | 2671 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 56,043 psi | 84% | 2923 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 80% | 54,534 psi | 82% | 2818 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 48,776 psi | 73% | 2799 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 80% | 40,727 psi | 61% | 2707 fps | 97% |
| Alliant Reloder-50 | <<locked>> | 82% | 38,522 psi | 58% | 2651 fps | 95.7% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 51,634 psi | 77% | 2835 fps | 99.4% |
| Bofors RP15 | <<locked>> | 80% | 52,170 psi | 78% | 2861 fps | 100% |
| Bofors RP30 | <<locked>> | 80% | 45,716 psi | 69% | 2769 fps | 100% |
| Bofors RP5 | <<locked>> | 80% | 56,043 psi | 84% | 2923 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 45,977 psi | 69% | 2766 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 80% | 56,275 psi | 84% | 2900 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 80% | 48,747 psi | 73% | 2890 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,892 psi | 43% | 1696 fps | 100% |
| Hodgdon US 869 | <<locked>> | 92% | 49,806 psi | 75% | 2835 fps | 95.2% |
| IMR 7828 SSC | <<locked>> | 80% | 54,172 psi | 81% | 2917 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 80% | 45,934 psi | 69% | 2684 fps | 95.7% |
| IMR 8133 Enduron | <<locked>> | 80% | 36,825 psi | 55% | 2598 fps | 98.8% |
| Lovex D100 | <<locked>> | 86% | 50,140 psi | 75% | 2792 fps | 95.8% |
| Lovex S071 | <<locked>> | 80% | 48,066 psi | 72% | 2703 fps | 100% |
| Norma 217 | <<locked>> | 80% | 37,869 psi | 57% | 2628 fps | 99.9% |
| Ramshot Grand | <<locked>> | 80% | 55,840 psi | 84% | 2940 fps | 100% |
| Ramshot LRT | 96.5 gr | 90% | 52,301 psi | 78% | 2933 fps | 96% |
| Ramshot Magnum | <<locked>> | 80% | 50,517 psi | 76% | 2808 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,747 psi | 45% | 1736 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 48,820 psi | 73% | 2864 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 44,643 psi | 67% | 2779 fps | 99.4% |
| Shooters World 50 BMG | <<locked>> | 86% | 50,140 psi | 75% | 2792 fps | 95.8% |
| SNPE Vectan SP 13 | <<locked>> | 86% | 38,856 psi | 58% | 2608 fps | 95.5% |
| Vihtavuori 20N29 | <<locked>> | 94% | 45,165 psi | 68% | 2756 fps | 95.9% |
| Vihtavuori 24N41 | <<locked>> | 90% | 50,227 psi | 75% | 2841 fps | 95.2% |
| Vihtavuori N165 | <<locked>> | 80% | 52,605 psi | 79% | 2795 fps | 100% |
| Vihtavuori N170 | <<locked>> | 80% | 45,643 psi | 68% | 2717 fps | 97.1% |
| Vihtavuori N565 | <<locked>> | 80% | 50,212 psi | 75% | 2835 fps | 100% |
| Vihtavuori N568 | <<locked>> | 80% | 45,295 psi | 68% | 2789 fps | 99.2% |
| Vihtavuori N570 | 84.2 gr | 80% | 43,540 psi | 65% | 2785 fps | 97.5% |
| Winchester Supreme 780 | <<locked>> | 80% | 55,434 psi | 83% | 2851 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 | 180gr | Sierra MatchKing. ADI AR 2218 delivers the highest muzzle velocity at 3,077 fps; across all powders the maximum-charge window runs from 1,893 fps to 3,077 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 180.0 gr projectile in 0.284" calls for a 1:10.0 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 | 180gr | Sierra MatchKing 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.