Load Specifications
Load data in caliber 7.21 Firebird with .283 | 160gr | Rhino Penetrator bullet and 54 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-33.
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>> | 84% | 58,508 psi | 88% | 3009 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 55,201 psi | 83% | 3071 fps | 98.8% |
| Accurate MAGPRO | <<locked>> | 82% | 57,870 psi | 87% | 3133 fps | 100% |
| ADI AR 2209 | <<locked>> | 82% | 59,103 psi | 89% | 3100 fps | 100% |
| ADI AR 2213 | <<locked>> | 84% | 58,262 psi | 87% | 3127 fps | 100% |
| ADI AR 2217 | <<locked>> | 92% | 58,320 psi | 87% | 3114 fps | 100% |
| ADI AR 2218 | <<locked>> | 96% | 59,364 psi | 89% | 3261 fps | 99.8% |
| ADI AR 2225 | <<locked>> | 94% | 58,320 psi | 87% | 3133 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 82% | 58,755 psi | 88% | 3091 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 84% | 58,798 psi | 88% | 3117 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 84% | 57,261 psi | 86% | 3012 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 88% | 58,436 psi | 88% | 3097 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 92% | 57,174 psi | 86% | 3159 fps | 99.4% |
| Alliant Reloder-50 | <<locked>> | 96% | 57,725 psi | 87% | 3159 fps | 99.2% |
| Baschieri & Pellagri 109 | <<locked>> | 86% | 58,117 psi | 87% | 3084 fps | 99.5% |
| Bofors RP15 | <<locked>> | 86% | 58,378 psi | 88% | 3110 fps | 100% |
| Bofors RP30 | <<locked>> | 90% | 58,363 psi | 87% | 3130 fps | 100% |
| Bofors RP5 | <<locked>> | 84% | 58,798 psi | 88% | 3117 fps | 100% |
| Hodgdon H1000 | <<locked>> | 90% | 59,553 psi | 89% | 3127 fps | 100% |
| Hodgdon H4831 | <<locked>> | 82% | 56,579 psi | 85% | 3051 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 84% | 59,451 psi | 89% | 3094 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 88% | 58,363 psi | 87% | 3199 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,159 psi | 57% | 1995 fps | 100% |
| Hodgdon US 869ᴾ | <<locked>> | 100% | 60,046 psi | 90% | 3140 fps | 96.3% |
| IMR 4955 Enduron | <<locked>> | 84% | 60,133 psi | 90% | 3081 fps | 100% |
| IMR 7828 SSC | <<locked>> | 84% | 57,087 psi | 86% | 3114 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 90% | 59,088 psi | 89% | 3045 fps | 97.4% |
| IMR 8133 Enduron | <<locked>> | 96% | 57,174 psi | 86% | 3123 fps | 100% |
| Lovex D100 | <<locked>> | 92% | 56,840 psi | 85% | 3035 fps | 96% |
| Lovex S071 | <<locked>> | 88% | 57,000 psi | 85% | 2989 fps | 100% |
| Norma 217 | <<locked>> | 96% | 58,842 psi | 88% | 3143 fps | 100% |
| Norma MRP | <<locked>> | 82% | 59,263 psi | 89% | 3130 fps | 100% |
| Ramshot Grand | <<locked>> | 84% | 58,842 psi | 88% | 3136 fps | 100% |
| Ramshot LRT | <<locked>> | 96% | 58,668 psi | 88% | 3179 fps | 96.2% |
| Ramshot Magnum | <<locked>> | 86% | 57,130 psi | 86% | 3054 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,146 psi | 59% | 2041 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 88% | 59,451 psi | 89% | 3182 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 90% | 58,494 psi | 88% | 3163 fps | 100% |
| Rottweil R 904 | <<locked>> | 82% | 59,132 psi | 89% | 3068 fps | 100% |
| Rottweil R 905 | <<locked>> | 82% | 58,784 psi | 88% | 3084 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 92% | 56,840 psi | 85% | 3035 fps | 96% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 56,753 psi | 85% | 3074 fps | 98.7% |
| SNPE Vectan Tubal 8000 | <<locked>> | 82% | 58,407 psi | 88% | 3081 fps | 100% |
| Somchem S385 | <<locked>> | 82% | 58,900 psi | 88% | 3045 fps | 100% |
| Vihtavuori 20N29ᴾ | <<locked>> | 100% | 50,183 psi | 75% | 2979 fps | 96% |
| Vihtavuori N165 | <<locked>> | 86% | 59,117 psi | 89% | 3035 fps | 100% |
| Vihtavuori N170 | <<locked>> | 90% | 58,813 psi | 88% | 3081 fps | 98.6% |
| Vihtavuori N555 | <<locked>> | 82% | 58,842 psi | 88% | 3041 fps | 100% |
| Vihtavuori N560 | <<locked>> | 82% | 58,407 psi | 88% | 3143 fps | 100% |
| Vihtavuori N565 | <<locked>> | 88% | 60,220 psi | 90% | 3143 fps | 100% |
| Vihtavuori N568 | <<locked>> | 90% | 58,523 psi | 88% | 3159 fps | 99.9% |
| Vihtavuori N570 | <<locked>> | 92% | 60,321 psi | 90% | 3235 fps | 99.5% |
| Winchester StaBALL HD | <<locked>> | 84% | 59,132 psi | 89% | 3114 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 84% | 58,755 psi | 88% | 3045 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% | 51,285 psi | 77% | 2904 fps | 100% |
| Accurate 8700 | <<locked>> | 92% | 41,031 psi | 62% | 2802 fps | 95.3% |
| Accurate MAGPRO | <<locked>> | 80% | 54,012 psi | 81% | 3071 fps | 99.8% |
| ADI AR 2209 | <<locked>> | 80% | 55,288 psi | 83% | 3041 fps | 100% |
| ADI AR 2213 | <<locked>> | 80% | 50,836 psi | 76% | 3002 fps | 99.9% |
| ADI AR 2217 | <<locked>> | 80% | 38,116 psi | 57% | 2743 fps | 98.4% |
| ADI AR 2218 | 92.4 gr | 86% | 40,814 psi | 61% | 2884 fps | 95.8% |
| ADI AR 2225 | <<locked>> | 80% | 35,476 psi | 53% | 2717 fps | 99.7% |
| Alliant Reloder-19 | <<locked>> | 80% | 55,085 psi | 83% | 3035 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 51,561 psi | 77% | 2999 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 80% | 50,140 psi | 75% | 2907 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 44,309 psi | 66% | 2871 fps | 100% |
| Alliant Reloder-33 | 89.7 gr | 82% | 39,349 psi | 59% | 2805 fps | 95.1% |
| Alliant Reloder-50 | <<locked>> | 88% | 42,917 psi | 64% | 2877 fps | 95.9% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 47,906 psi | 72% | 2904 fps | 98% |
| Bofors RP15 | <<locked>> | 80% | 47,964 psi | 72% | 2936 fps | 99.9% |
| Bofors RP30 | <<locked>> | 80% | 41,510 psi | 62% | 2825 fps | 99% |
| Bofors RP5 | <<locked>> | 80% | 51,561 psi | 77% | 2999 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 41,640 psi | 62% | 2818 fps | 99.4% |
| Hodgdon H4831 | <<locked>> | 80% | 52,953 psi | 79% | 2992 fps | 99.8% |
| Hodgdon H4831 SC | <<locked>> | 80% | 52,083 psi | 78% | 2976 fps | 99.8% |
| Hodgdon Retumbo | <<locked>> | 80% | 43,656 psi | 65% | 2946 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,689 psi | 43% | 1788 fps | 100% |
| Hodgdon US 869 | <<locked>> | 98% | 55,985 psi | 84% | 3071 fps | 95.3% |
| IMR 4955 Enduron | <<locked>> | 80% | 52,997 psi | 79% | 2966 fps | 99.9% |
| IMR 7828 SSC | <<locked>> | 80% | 49,559 psi | 74% | 2986 fps | 99.8% |
| IMR 7977 Enduron | <<locked>> | 84% | 48,646 psi | 73% | 2861 fps | 95% |
| IMR 8133 Enduron | <<locked>> | 80% | 33,040 psi | 50% | 2631 fps | 96.3% |
| Lovex D100 | <<locked>> | 90% | 53,055 psi | 80% | 2969 fps | 95.1% |
| Lovex S071 | <<locked>> | 80% | 44,237 psi | 66% | 2779 fps | 100% |
| Norma 217 | <<locked>> | 80% | 33,605 psi | 50% | 2657 fps | 98.6% |
| Norma MRP | <<locked>> | 80% | 55,274 psi | 83% | 3071 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 50,705 psi | 76% | 3009 fps | 100% |
| Ramshot LRT | <<locked>> | 94% | 54,679 psi | 82% | 3110 fps | 95.2% |
| Ramshot Magnum | <<locked>> | 80% | 45,672 psi | 68% | 2871 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,486 psi | 44% | 1827 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 43,555 psi | 65% | 2920 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 40,016 psi | 60% | 2812 fps | 97.5% |
| Rottweil R 904 | <<locked>> | 80% | 55,419 psi | 83% | 3009 fps | 100% |
| Rottweil R 905 | <<locked>> | 80% | 55,027 psi | 82% | 3025 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 90% | 53,055 psi | 80% | 2969 fps | 95.1% |
| SNPE Vectan SP 13 | <<locked>> | 92% | 43,149 psi | 65% | 2825 fps | 95.6% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 54,679 psi | 82% | 3022 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 55,274 psi | 83% | 2992 fps | 100% |
| Vihtavuori 20N29 | <<locked>> | 98% | 46,688 psi | 70% | 2910 fps | 95% |
| Vihtavuori N165 | <<locked>> | 80% | 48,617 psi | 73% | 2871 fps | 100% |
| Vihtavuori N170 | <<locked>> | 82% | 44,904 psi | 67% | 2828 fps | 95.5% |
| Vihtavuori N555 | <<locked>> | 80% | 55,143 psi | 83% | 2989 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 54,505 psi | 82% | 3077 fps | 99.9% |
| Vihtavuori N565 | <<locked>> | 80% | 45,876 psi | 69% | 2894 fps | 99.3% |
| Vihtavuori N568 | <<locked>> | 80% | 40,886 psi | 61% | 2828 fps | 97.3% |
| Vihtavuori N570 | 86.3 gr | 82% | 42,090 psi | 63% | 2887 fps | 95.7% |
| Winchester StaBALL HD | <<locked>> | 80% | 50,865 psi | 76% | 2995 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 51,242 psi | 77% | 2927 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 54 powders for 7.21 Firebird loaded with the .283 | 160gr | Rhino Penetrator. ADI AR 2218 delivers the highest muzzle velocity at 3,261 fps; across all powders the maximum-charge window runs from 1,995 fps to 3,261 fps. Accurate 8700 gives the best case fill at 100 %, and 54 of the 54 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 160.0 gr projectile in 0.283" calls for a 1:9.5 twist; slower twists will usually not stabilise this weight. Accurate 8700, Hodgdon TrailBoss, Hodgdon US 869 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-33 rank at the top here: for 7.21 Firebird with the .283 | 160gr | Rhino Penetrator 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.