Load Specifications
Load data in caliber 7.21 Firebird with .284 | 170gr | Rhino Solid Shank 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% | 57,754 psi | 87% | 2923 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 59,364 psi | 89% | 3061 fps | 99.6% |
| ADI AR 2213 | <<locked>> | 82% | 57,522 psi | 86% | 3035 fps | 100% |
| ADI AR 2217 | <<locked>> | 90% | 57,943 psi | 87% | 3028 fps | 100% |
| ADI AR 2218 | <<locked>> | 94% | 59,190 psi | 89% | 3182 fps | 100% |
| ADI AR 2225 | <<locked>> | 92% | 58,247 psi | 87% | 3051 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 82% | 58,146 psi | 87% | 3028 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 82% | 56,637 psi | 85% | 2923 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 86% | 57,957 psi | 87% | 3009 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 90% | 57,116 psi | 86% | 3084 fps | 99.7% |
| Alliant Reloder-50 | <<locked>> | 94% | 57,783 psi | 87% | 3084 fps | 99.5% |
| Baschieri & Pellagri 109 | <<locked>> | 84% | 57,276 psi | 86% | 2999 fps | 99.7% |
| Bofors RP15 | <<locked>> | 84% | 57,740 psi | 87% | 3022 fps | 100% |
| Bofors RP30 | <<locked>> | 88% | 57,899 psi | 87% | 3041 fps | 100% |
| Bofors RP5 | <<locked>> | 82% | 58,146 psi | 87% | 3028 fps | 100% |
| Hodgdon H1000 | <<locked>> | 88% | 59,146 psi | 89% | 3041 fps | 100% |
| Hodgdon H4831 | <<locked>> | 82% | 59,654 psi | 89% | 3022 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 82% | 58,523 psi | 88% | 3005 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 86% | 58,407 psi | 88% | 3117 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,276 psi | 57% | 1946 fps | 100% |
| Hodgdon US 869 | <<locked>> | 98% | 59,756 psi | 90% | 3064 fps | 97% |
| IMR 4955 Enduron | <<locked>> | 82% | 59,263 psi | 89% | 2992 fps | 100% |
| IMR 7828 SSC | <<locked>> | 84% | 60,365 psi | 90% | 3081 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 88% | 58,117 psi | 87% | 2963 fps | 97.9% |
| IMR 8133 Enduron | <<locked>> | 94% | 57,188 psi | 86% | 3045 fps | 100% |
| Lovex D100 | <<locked>> | 92% | 60,336 psi | 90% | 3025 fps | 97.5% |
| Lovex S071 | <<locked>> | 88% | 60,205 psi | 90% | 2956 fps | 100% |
| Norma 217 | <<locked>> | 94% | 58,987 psi | 88% | 3064 fps | 100% |
| Ramshot Grand | <<locked>> | 82% | 58,131 psi | 87% | 3045 fps | 100% |
| Ramshot LRT | <<locked>> | 94% | 58,363 psi | 87% | 3104 fps | 96.8% |
| Ramshot Magnum | <<locked>> | 84% | 56,565 psi | 85% | 2969 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,436 psi | 59% | 1991 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 86% | 59,263 psi | 89% | 3094 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 88% | 58,175 psi | 87% | 3077 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 92% | 60,336 psi | 90% | 3025 fps | 97.5% |
| SNPE Vectan SP 13 | <<locked>> | 98% | 56,608 psi | 85% | 3002 fps | 99.2% |
| Vihtavuori 20N29ᴾ | <<locked>> | 100% | 53,969 psi | 81% | 2979 fps | 97.6% |
| Vihtavuori 24N41 | <<locked>> | 96% | 60,191 psi | 90% | 3074 fps | 97% |
| Vihtavuori N165 | <<locked>> | 84% | 58,450 psi | 88% | 2949 fps | 100% |
| Vihtavuori N170 | <<locked>> | 88% | 58,175 psi | 87% | 3002 fps | 99% |
| Vihtavuori N565 | <<locked>> | 86% | 59,625 psi | 89% | 3054 fps | 100% |
| Vihtavuori N568 | <<locked>> | 88% | 58,131 psi | 87% | 3077 fps | 100% |
| Vihtavuori N570 | <<locked>> | 90% | 60,176 psi | 90% | 3156 fps | 99.7% |
| Winchester StaBALL HD | <<locked>> | 82% | 58,813 psi | 88% | 3022 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 82% | 57,812 psi | 87% | 2956 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% | 54,128 psi | 81% | 2871 fps | 100% |
| Accurate 8700 | <<locked>> | 88% | 38,276 psi | 57% | 2674 fps | 95% |
| ADI AR 2213 | <<locked>> | 80% | 53,795 psi | 81% | 2976 fps | 100% |
| ADI AR 2217 | <<locked>> | 80% | 40,727 psi | 61% | 2730 fps | 99.4% |
| ADI AR 2218 | 89.2 gr | 82% | 37,768 psi | 57% | 2743 fps | 95.4% |
| ADI AR 2225 | <<locked>> | 80% | 38,101 psi | 57% | 2703 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 54,491 psi | 82% | 2969 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 80% | 53,084 psi | 80% | 2874 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 47,268 psi | 71% | 2844 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 80% | 39,305 psi | 59% | 2736 fps | 95.9% |
| Alliant Reloder-50 | 92.8 gr | 84% | 40,030 psi | 60% | 2743 fps | 95.6% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 50,285 psi | 75% | 2881 fps | 99% |
| Bofors RP15 | <<locked>> | 80% | 50,720 psi | 76% | 2907 fps | 100% |
| Bofors RP30 | <<locked>> | 80% | 44,280 psi | 66% | 2808 fps | 99.7% |
| Bofors RP5 | <<locked>> | 80% | 54,491 psi | 82% | 2969 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 44,498 psi | 67% | 2805 fps | 99.9% |
| Hodgdon H4831 | <<locked>> | 80% | 55,724 psi | 84% | 2963 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 80% | 54,839 psi | 82% | 2949 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 80% | 46,992 psi | 70% | 2930 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,776 psi | 43% | 1742 fps | 100% |
| Hodgdon US 869 | <<locked>> | 94% | 51,793 psi | 78% | 2930 fps | 95.1% |
| IMR 4955 Enduron | <<locked>> | 80% | 55,521 psi | 83% | 2936 fps | 100% |
| IMR 7828 SSC | <<locked>> | 80% | 52,591 psi | 79% | 2963 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 82% | 47,819 psi | 72% | 2782 fps | 95.6% |
| IMR 8133 Enduron | <<locked>> | 80% | 35,534 psi | 53% | 2628 fps | 97.9% |
| Lovex D100 | <<locked>> | 88% | 52,373 psi | 79% | 2894 fps | 95.8% |
| Lovex S071 | <<locked>> | 80% | 46,659 psi | 70% | 2749 fps | 100% |
| Norma 217 | <<locked>> | 80% | 36,347 psi | 54% | 2654 fps | 99.6% |
| Ramshot Grand | <<locked>> | 80% | 54,041 psi | 81% | 2986 fps | 100% |
| Ramshot LRT | <<locked>> | 92% | 54,273 psi | 81% | 3035 fps | 95.9% |
| Ramshot Magnum | <<locked>> | 80% | 48,849 psi | 73% | 2851 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,733 psi | 45% | 1785 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 47,094 psi | 71% | 2907 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 43,105 psi | 65% | 2808 fps | 98.9% |
| Shooters World 50 BMG | <<locked>> | 88% | 52,373 psi | 79% | 2894 fps | 95.8% |
| SNPE Vectan SP 13 | <<locked>> | 88% | 40,263 psi | 60% | 2697 fps | 95.4% |
| Vihtavuori 20N29 | <<locked>> | 96% | 46,891 psi | 70% | 2848 fps | 95.8% |
| Vihtavuori 24N41 | <<locked>> | 92% | 52,214 psi | 78% | 2940 fps | 95.1% |
| Vihtavuori N165 | <<locked>> | 80% | 51,256 psi | 77% | 2841 fps | 100% |
| Vihtavuori N170 | <<locked>> | 80% | 44,338 psi | 66% | 2753 fps | 96.1% |
| Vihtavuori N565 | <<locked>> | 80% | 48,704 psi | 73% | 2877 fps | 99.8% |
| Vihtavuori N568 | <<locked>> | 80% | 43,874 psi | 66% | 2822 fps | 98.6% |
| Vihtavuori N570 | 85.2 gr | 80% | 41,945 psi | 63% | 2812 fps | 96.4% |
| Winchester StaBALL HD | <<locked>> | 80% | 54,607 psi | 82% | 2963 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 53,983 psi | 81% | 2900 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 | 170gr | Rhino Solid Shank. ADI AR 2218 delivers the highest muzzle velocity at 3,182 fps; across all powders the maximum-charge window runs from 1,946 fps to 3,182 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 170.0 gr projectile in 0.284" calls for a 1:11.0 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 | 170gr | Rhino Solid Shank 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.