Load Specifications
Load data in caliber 7.21 Firebird with .284 | 168gr | Sierra MatchKing bullet and 45 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>> | 82% | 57,624 psi | 86% | 2936 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 59,176 psi | 89% | 3074 fps | 99.6% |
| ADI AR 2213 | <<locked>> | 82% | 57,421 psi | 86% | 3051 fps | 100% |
| ADI AR 2217 | <<locked>> | 90% | 57,725 psi | 87% | 3045 fps | 100% |
| ADI AR 2218 | <<locked>> | 94% | 59,059 psi | 89% | 3196 fps | 99.9% |
| ADI AR 2225 | <<locked>> | 92% | 58,204 psi | 87% | 3068 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 82% | 58,015 psi | 87% | 3041 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 84% | 60,307 psi | 90% | 2989 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 86% | 57,812 psi | 87% | 3025 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 90% | 57,014 psi | 85% | 3097 fps | 99.6% |
| Alliant Reloder-50 | <<locked>> | 94% | 57,653 psi | 86% | 3100 fps | 99.5% |
| Baschieri & Pellagri 109 | <<locked>> | 84% | 57,130 psi | 86% | 3009 fps | 99.7% |
| Bofors RP15 | <<locked>> | 84% | 57,609 psi | 86% | 3038 fps | 100% |
| Bofors RP30 | <<locked>> | 88% | 57,899 psi | 87% | 3061 fps | 100% |
| Bofors RP5 | <<locked>> | 82% | 58,015 psi | 87% | 3041 fps | 100% |
| Hodgdon H1000 | <<locked>> | 88% | 58,958 psi | 88% | 3058 fps | 100% |
| Hodgdon H4831 | <<locked>> | 82% | 59,553 psi | 89% | 3038 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 82% | 58,436 psi | 88% | 3018 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 86% | 58,204 psi | 87% | 3130 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,261 psi | 57% | 1959 fps | 100% |
| Hodgdon US 869 | <<locked>> | 98% | 59,582 psi | 89% | 3077 fps | 96.9% |
| IMR 4955 Enduron | <<locked>> | 82% | 58,987 psi | 88% | 3005 fps | 100% |
| IMR 7828 SSC | <<locked>> | 84% | 60,234 psi | 90% | 3097 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 88% | 57,986 psi | 87% | 2976 fps | 97.8% |
| IMR 8133 Enduron | <<locked>> | 94% | 56,985 psi | 85% | 3058 fps | 100% |
| Lovex D100 | <<locked>> | 92% | 60,263 psi | 90% | 3038 fps | 97.4% |
| Lovex S071 | <<locked>> | 88% | 60,104 psi | 90% | 2969 fps | 100% |
| Norma 217 | <<locked>> | 94% | 58,972 psi | 88% | 3081 fps | 100% |
| Ramshot Grand | <<locked>> | 82% | 57,972 psi | 87% | 3064 fps | 100% |
| Ramshot LRT | <<locked>> | 94% | 58,262 psi | 87% | 3117 fps | 96.7% |
| Ramshot Magnum | <<locked>> | 84% | 56,405 psi | 85% | 2982 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,407 psi | 59% | 2005 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 86% | 59,016 psi | 88% | 3110 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 88% | 57,899 psi | 87% | 3091 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 92% | 60,263 psi | 90% | 3038 fps | 97.4% |
| SNPE Vectan SP 13 | <<locked>> | 98% | 56,521 psi | 85% | 3015 fps | 99.1% |
| Vihtavuori 20N29ᴾ | <<locked>> | 100% | 53,795 psi | 81% | 2992 fps | 97.5% |
| Vihtavuori 24N41 | <<locked>> | 96% | 60,075 psi | 90% | 3087 fps | 96.9% |
| Vihtavuori N165 | <<locked>> | 84% | 58,334 psi | 87% | 2963 fps | 100% |
| Vihtavuori N170 | <<locked>> | 88% | 57,986 psi | 87% | 3015 fps | 98.9% |
| Vihtavuori N565 | <<locked>> | 86% | 59,466 psi | 89% | 3071 fps | 100% |
| Vihtavuori N568 | <<locked>> | 88% | 58,117 psi | 87% | 3094 fps | 100% |
| Vihtavuori N570 | <<locked>> | 90% | 59,915 psi | 90% | 3169 fps | 99.7% |
| Winchester StaBALL HD | <<locked>> | 82% | 58,595 psi | 88% | 3035 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 82% | 57,711 psi | 87% | 2972 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% | 53,867 psi | 81% | 2884 fps | 100% |
| Accurate 8700 | <<locked>> | 90% | 40,988 psi | 61% | 2746 fps | 96% |
| ADI AR 2213 | <<locked>> | 80% | 53,534 psi | 80% | 2989 fps | 100% |
| ADI AR 2217 | <<locked>> | 80% | 40,654 psi | 61% | 2743 fps | 99.3% |
| ADI AR 2218 | 89.7 gr | 82% | 37,637 psi | 56% | 2756 fps | 95.2% |
| ADI AR 2225 | <<locked>> | 80% | 38,000 psi | 57% | 2720 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 54,230 psi | 81% | 2986 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 80% | 53,011 psi | 79% | 2887 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 47,195 psi | 71% | 2861 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 80% | 39,160 psi | 59% | 2746 fps | 95.8% |
| Alliant Reloder-50 | 93.3 gr | 84% | 39,856 psi | 60% | 2753 fps | 95.4% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 50,183 psi | 75% | 2894 fps | 98.9% |
| Bofors RP15 | <<locked>> | 80% | 50,662 psi | 76% | 2923 fps | 100% |
| Bofors RP30 | <<locked>> | 80% | 44,048 psi | 66% | 2818 fps | 99.7% |
| Bofors RP5 | <<locked>> | 80% | 54,230 psi | 81% | 2986 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 44,396 psi | 67% | 2818 fps | 99.9% |
| Hodgdon H4831 | <<locked>> | 80% | 55,651 psi | 83% | 2979 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 80% | 54,578 psi | 82% | 2959 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 80% | 46,876 psi | 70% | 2946 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,819 psi | 43% | 1755 fps | 100% |
| Hodgdon US 869 | <<locked>> | 96% | 55,506 psi | 83% | 3012 fps | 96% |
| IMR 4955 Enduron | <<locked>> | 80% | 55,434 psi | 83% | 2949 fps | 100% |
| IMR 7828 SSC | <<locked>> | 80% | 52,518 psi | 79% | 2979 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 82% | 47,776 psi | 72% | 2795 fps | 95.5% |
| IMR 8133 Enduron | <<locked>> | 80% | 35,491 psi | 53% | 2641 fps | 97.9% |
| Lovex D100 | <<locked>> | 88% | 52,156 psi | 78% | 2904 fps | 95.6% |
| Lovex S071 | <<locked>> | 80% | 46,659 psi | 70% | 2766 fps | 100% |
| Norma 217 | <<locked>> | 80% | 36,274 psi | 54% | 2667 fps | 99.5% |
| Ramshot Grand | <<locked>> | 80% | 53,925 psi | 81% | 2999 fps | 100% |
| Ramshot LRT | <<locked>> | 92% | 54,201 psi | 81% | 3048 fps | 95.8% |
| Ramshot Magnum | <<locked>> | 80% | 48,718 psi | 73% | 2864 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,631 psi | 44% | 1798 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 46,920 psi | 70% | 2920 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 42,946 psi | 64% | 2822 fps | 98.8% |
| Shooters World 50 BMG | <<locked>> | 88% | 52,156 psi | 78% | 2904 fps | 95.6% |
| SNPE Vectan SP 13 | <<locked>> | 88% | 40,132 psi | 60% | 2707 fps | 95.2% |
| Vihtavuori 20N29 | <<locked>> | 96% | 46,775 psi | 70% | 2861 fps | 95.7% |
| Vihtavuori 24N41 | <<locked>> | 92% | 52,127 psi | 78% | 2953 fps | 95% |
| Vihtavuori N165 | <<locked>> | 80% | 51,024 psi | 76% | 2854 fps | 100% |
| Vihtavuori N170 | <<locked>> | 80% | 44,251 psi | 66% | 2766 fps | 96% |
| Vihtavuori N565 | <<locked>> | 80% | 48,617 psi | 73% | 2890 fps | 99.8% |
| Vihtavuori N568 | <<locked>> | 80% | 43,758 psi | 66% | 2835 fps | 98.5% |
| Vihtavuori N570 | 85.7 gr | 80% | 41,829 psi | 63% | 2825 fps | 96.2% |
| Winchester StaBALL HD | <<locked>> | 80% | 54,534 psi | 82% | 2979 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 53,882 psi | 81% | 2913 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 45 powders for 7.21 Firebird loaded with the .284 | 168gr | Sierra MatchKing. ADI AR 2218 delivers the highest muzzle velocity at 3,196 fps; across all powders the maximum-charge window runs from 1,959 fps to 3,196 fps. Accurate 8700 gives the best case fill at 100 %, and 45 of the 45 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 168.0 gr projectile in 0.284" calls for a 1:10.5 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 | 168gr | 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.