Load Specifications
Load data in caliber 7.21 Firebird with .284 | 175gr | Alaska Bullet Works Kodiak PP SPBC 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.
A valid access license is required to use the Personalized Load Calculator.
You can find more information in our FAQ: How can I use the Personalized Load Calculator?
Max Load - Barrel Length: 26"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 3100 | <<locked>> | 82% | 59,466 psi | 89% | 2907 fps | 100% |
| Accurate 8700 | <<locked>> | 98% | 57,508 psi | 86% | 2999 fps | 99.6% |
| ADI AR 2213 | <<locked>> | 82% | 59,335 psi | 89% | 3025 fps | 100% |
| ADI AR 2217 | <<locked>> | 90% | 59,843 psi | 90% | 3018 fps | 100% |
| ADI AR 2218 | <<locked>> | 92% | 57,217 psi | 86% | 3114 fps | 100% |
| ADI AR 2225 | <<locked>> | 90% | 56,420 psi | 85% | 2986 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 82% | 59,915 psi | 90% | 3015 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 82% | 58,233 psi | 87% | 2907 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 86% | 59,872 psi | 90% | 2995 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 90% | 59,263 psi | 89% | 3081 fps | 99.9% |
| Alliant Reloder-50 | <<locked>> | 94% | 60,017 psi | 90% | 3084 fps | 99.8% |
| Baschieri & Pellagri 109 | <<locked>> | 84% | 58,755 psi | 88% | 2986 fps | 99.9% |
| Bofors RP15 | <<locked>> | 84% | 59,480 psi | 89% | 3009 fps | 100% |
| Bofors RP30 | <<locked>> | 88% | 59,973 psi | 90% | 3035 fps | 100% |
| Bofors RP5 | <<locked>> | 82% | 59,915 psi | 90% | 3015 fps | 100% |
| Hodgdon H1000 | <<locked>> | 86% | 57,101 psi | 86% | 2976 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 82% | 60,176 psi | 90% | 2992 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 84% | 56,405 psi | 85% | 3045 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,334 psi | 57% | 1926 fps | 100% |
| Hodgdon US 869 | <<locked>> | 96% | 57,711 psi | 87% | 3002 fps | 96.9% |
| IMR 7828 SSC | <<locked>> | 82% | 58,117 psi | 87% | 3012 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 88% | 59,596 psi | 89% | 2953 fps | 98.4% |
| IMR 8133 Enduron | <<locked>> | 94% | 59,161 psi | 89% | 3038 fps | 100% |
| Lovex D100 | <<locked>> | 90% | 58,001 psi | 87% | 2953 fps | 97.4% |
| Lovex S071 | <<locked>> | 86% | 58,131 psi | 87% | 2890 fps | 100% |
| Norma 217 | <<locked>> | 92% | 57,203 psi | 86% | 2999 fps | 100% |
| Ramshot Grand | <<locked>> | 82% | 60,147 psi | 90% | 3038 fps | 100% |
| Ramshot LRT | <<locked>> | 92% | 56,434 psi | 85% | 3038 fps | 96.8% |
| Ramshot Magnum | <<locked>> | 84% | 58,450 psi | 88% | 2959 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,494 psi | 59% | 1969 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 84% | 57,029 psi | 85% | 3022 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 88% | 60,162 psi | 90% | 3071 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 90% | 58,001 psi | 87% | 2953 fps | 97.4% |
| SNPE Vectan SP 13 | <<locked>> | 98% | 58,755 psi | 88% | 3002 fps | 99.6% |
| Vihtavuori 20N29ᴾ | <<locked>> | 100% | 56,159 psi | 84% | 2982 fps | 98.3% |
| Vihtavuori 24N41 | <<locked>> | 94% | 58,044 psi | 87% | 3009 fps | 96.9% |
| Vihtavuori N165 | <<locked>> | 84% | 59,915 psi | 90% | 2933 fps | 100% |
| Vihtavuori N170 | <<locked>> | 88% | 59,828 psi | 90% | 2995 fps | 99.3% |
| Vihtavuori N565 | <<locked>> | 84% | 57,551 psi | 86% | 2989 fps | 100% |
| Vihtavuori N568 | <<locked>> | 88% | 60,263 psi | 90% | 3071 fps | 100% |
| Vihtavuori N570 | <<locked>> | 88% | 58,073 psi | 87% | 3084 fps | 99.7% |
| Winchester Supreme 780 | <<locked>> | 82% | 59,466 psi | 89% | 2943 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% | 2854 fps | 100% |
| Accurate 8700 | <<locked>> | 88% | 39,798 psi | 60% | 2677 fps | 96.1% |
| ADI AR 2213 | <<locked>> | 80% | 55,361 psi | 83% | 2963 fps | 100% |
| ADI AR 2217 | <<locked>> | 80% | 42,148 psi | 63% | 2723 fps | 99.7% |
| ADI AR 2218 | 87.8 gr | 80% | 36,376 psi | 55% | 2677 fps | 95.2% |
| ADI AR 2225 | <<locked>> | 80% | 39,697 psi | 60% | 2703 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 56,028 psi | 84% | 2956 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 80% | 54,621 psi | 82% | 2858 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 48,979 psi | 73% | 2835 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 80% | 40,886 psi | 61% | 2740 fps | 96.8% |
| Alliant Reloder-50 | <<locked>> | 82% | 38,725 psi | 58% | 2680 fps | 95.4% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 51,648 psi | 77% | 2871 fps | 99.3% |
| Bofors RP15 | <<locked>> | 80% | 52,199 psi | 78% | 2897 fps | 100% |
| Bofors RP30 | <<locked>> | 80% | 45,745 psi | 69% | 2802 fps | 99.9% |
| Bofors RP5 | <<locked>> | 80% | 56,028 psi | 84% | 2956 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 45,992 psi | 69% | 2795 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 80% | 56,275 psi | 84% | 2933 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 80% | 48,921 psi | 73% | 2923 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,906 psi | 43% | 1726 fps | 100% |
| Hodgdon US 869 | <<locked>> | 92% | 50,140 psi | 75% | 2871 fps | 95% |
| IMR 7828 SSC | <<locked>> | 80% | 54,360 psi | 81% | 2953 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 80% | 45,977 psi | 69% | 2717 fps | 95.5% |
| IMR 8133 Enduron | <<locked>> | 80% | 36,898 psi | 55% | 2628 fps | 98.6% |
| Lovex D100 | <<locked>> | 86% | 50,256 psi | 75% | 2825 fps | 95.6% |
| Lovex S071 | <<locked>> | 80% | 48,066 psi | 72% | 2736 fps | 100% |
| Norma 217 | <<locked>> | 80% | 37,913 psi | 57% | 2657 fps | 99.9% |
| Ramshot Grand | <<locked>> | 80% | 55,956 psi | 84% | 2976 fps | 100% |
| Ramshot LRT | 98.6 gr | 90% | 52,533 psi | 79% | 2969 fps | 95.8% |
| Ramshot Magnum | <<locked>> | 80% | 50,589 psi | 76% | 2841 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,733 psi | 45% | 1765 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 49,023 psi | 73% | 2900 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 44,773 psi | 67% | 2808 fps | 99.3% |
| Shooters World 50 BMG | <<locked>> | 86% | 50,256 psi | 75% | 2825 fps | 95.6% |
| SNPE Vectan SP 13 | <<locked>> | 86% | 38,943 psi | 58% | 2635 fps | 95.3% |
| Vihtavuori 20N29 | <<locked>> | 94% | 45,440 psi | 68% | 2789 fps | 95.8% |
| Vihtavuori 24N41 | <<locked>> | 90% | 50,430 psi | 76% | 2874 fps | 95% |
| Vihtavuori N165 | <<locked>> | 80% | 52,634 psi | 79% | 2828 fps | 100% |
| Vihtavuori N170 | <<locked>> | 80% | 45,745 psi | 69% | 2749 fps | 96.9% |
| Vihtavuori N565 | <<locked>> | 80% | 50,328 psi | 75% | 2871 fps | 100% |
| Vihtavuori N568 | <<locked>> | 80% | 45,498 psi | 68% | 2818 fps | 99.1% |
| Vihtavuori N570 | 86 gr | 80% | 43,627 psi | 65% | 2815 fps | 97.2% |
| Winchester Supreme 780 | <<locked>> | 80% | 55,579 psi | 83% | 2887 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 43 powders for 7.21 Firebird loaded with the .284 | 175gr | Alaska Bullet Works Kodiak PP SPBC. ADI AR 2218 delivers the highest muzzle velocity at 3,114 fps; across all powders the maximum-charge window runs from 1,926 fps to 3,114 fps. Hodgdon TrailBoss gives the best case fill at 100 %, and 43 of the 43 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 175.0 gr projectile in 0.284" calls for a 1:12.0 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 | 175gr | Alaska Bullet Works Kodiak PP SPBC they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Hodgdon 50BMG burn incompletely and react more sensitively to barrel length and temperature. Always begin at the start load and work up in small increments while checking case and primer for pressure signs.