Load Specifications
Load data in caliber 7.21 Firebird with .284 | 155gr | Frontier PH HPFB bullet and 52 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are ADI AR 2218, Hodgdon Retumbo and Vihtavuori N570.
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% | 57,290 psi | 86% | 3031 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 53,824 psi | 81% | 3084 fps | 98.4% |
| Accurate MAGPRO | <<locked>> | 82% | 56,550 psi | 85% | 3153 fps | 99.8% |
| ADI AR 2209 | <<locked>> | 82% | 58,102 psi | 87% | 3127 fps | 100% |
| ADI AR 2213 | <<locked>> | 84% | 57,174 psi | 86% | 3150 fps | 100% |
| ADI AR 2217 | <<locked>> | 92% | 56,855 psi | 85% | 3133 fps | 100% |
| ADI AR 2218 | <<locked>> | 96% | 57,870 psi | 87% | 3274 fps | 99.6% |
| ADI AR 2225 | <<locked>> | 94% | 56,956 psi | 85% | 3156 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 82% | 57,595 psi | 86% | 3114 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 84% | 57,754 psi | 87% | 3143 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 86% | 59,828 psi | 90% | 3091 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 88% | 57,014 psi | 85% | 3120 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 94% | 60,118 psi | 90% | 3248 fps | 99.5% |
| Alliant Reloder-50 | <<locked>> | 96% | 56,260 psi | 84% | 3173 fps | 98.8% |
| Baschieri & Pellagri 109 | <<locked>> | 86% | 57,159 psi | 86% | 3104 fps | 99.3% |
| Bofors RP15 | <<locked>> | 86% | 57,145 psi | 86% | 3133 fps | 100% |
| Bofors RP30 | <<locked>> | 90% | 56,956 psi | 85% | 3150 fps | 100% |
| Bofors RP5 | <<locked>> | 84% | 57,754 psi | 87% | 3143 fps | 100% |
| Hodgdon H1000 | <<locked>> | 90% | 58,305 psi | 87% | 3150 fps | 100% |
| Hodgdon H4831 | <<locked>> | 84% | 59,408 psi | 89% | 3136 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 84% | 58,450 psi | 88% | 3120 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 88% | 56,971 psi | 85% | 3222 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,014 psi | 57% | 2021 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 84% | 59,263 psi | 89% | 3107 fps | 100% |
| IMR 7828 SSC | <<locked>> | 86% | 59,698 psi | 89% | 3192 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 90% | 57,957 psi | 87% | 3061 fps | 96.9% |
| IMR 8133 Enduron | <<locked>> | 98% | 59,611 psi | 89% | 3202 fps | 100% |
| Lovex D100 | <<locked>> | 94% | 59,915 psi | 90% | 3120 fps | 96.4% |
| Lovex S071 | <<locked>> | 90% | 59,611 psi | 89% | 3068 fps | 100% |
| Norma 217 | <<locked>> | 96% | 57,406 psi | 86% | 3163 fps | 100% |
| Norma MRP | <<locked>> | 82% | 57,914 psi | 87% | 3153 fps | 100% |
| Ramshot Grand | <<locked>> | 84% | 57,363 psi | 86% | 3156 fps | 100% |
| Ramshot Magnum | <<locked>> | 88% | 60,133 psi | 90% | 3136 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,131 psi | 59% | 2070 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 88% | 57,769 psi | 87% | 3202 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 90% | 56,913 psi | 85% | 3176 fps | 99.9% |
| Rottweil R 904 | <<locked>> | 82% | 58,218 psi | 87% | 3094 fps | 100% |
| Rottweil R 905 | <<locked>> | 82% | 57,609 psi | 86% | 3107 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 94% | 59,915 psi | 90% | 3120 fps | 96.4% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 55,448 psi | 83% | 3087 fps | 98.3% |
| SNPE Vectan Tubal 8000 | <<locked>> | 82% | 57,246 psi | 86% | 3104 fps | 100% |
| Somchem S361 | <<locked>> | 82% | 59,582 psi | 89% | 3081 fps | 100% |
| Somchem S385 | <<locked>> | 82% | 57,769 psi | 87% | 3068 fps | 100% |
| Vihtavuori N165 | <<locked>> | 86% | 58,088 psi | 87% | 3061 fps | 100% |
| Vihtavuori N170 | <<locked>> | 90% | 57,754 psi | 87% | 3104 fps | 98.2% |
| Vihtavuori N555 | <<locked>> | 82% | 57,624 psi | 86% | 3068 fps | 100% |
| Vihtavuori N560 | <<locked>> | 82% | 57,116 psi | 86% | 3159 fps | 100% |
| Vihtavuori N565 | <<locked>> | 88% | 58,856 psi | 88% | 3163 fps | 100% |
| Vihtavuori N568 | <<locked>> | 90% | 57,246 psi | 86% | 3179 fps | 99.8% |
| Vihtavuori N570 | <<locked>> | 92% | 58,914 psi | 88% | 3255 fps | 99.2% |
| Winchester StaBALL HD | <<locked>> | 84% | 57,522 psi | 86% | 3136 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 84% | 57,725 psi | 87% | 3071 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% | 50,169 psi | 75% | 2923 fps | 100% |
| Accurate 8700 | <<locked>> | 94% | 43,047 psi | 65% | 2877 fps | 95.7% |
| Accurate MAGPRO | <<locked>> | 80% | 52,779 psi | 79% | 3087 fps | 99.5% |
| ADI AR 2209 | <<locked>> | 80% | 54,346 psi | 81% | 3068 fps | 100% |
| ADI AR 2213 | <<locked>> | 80% | 49,676 psi | 74% | 3018 fps | 99.7% |
| ADI AR 2217 | <<locked>> | 80% | 37,173 psi | 56% | 2753 fps | 97.8% |
| ADI AR 2218 | 94.7 gr | 88% | 42,873 psi | 64% | 2969 fps | 96.2% |
| ADI AR 2225 | <<locked>> | 80% | 34,534 psi | 52% | 2726 fps | 99.3% |
| Alliant Reloder-19 | <<locked>> | 80% | 53,983 psi | 81% | 3054 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 50,459 psi | 76% | 3022 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 80% | 49,023 psi | 73% | 2930 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 43,352 psi | 65% | 2890 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 84% | 41,234 psi | 62% | 2884 fps | 95.5% |
| Alliant Reloder-50 | <<locked>> | 88% | 41,640 psi | 62% | 2881 fps | 95% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 46,934 psi | 70% | 2920 fps | 97.5% |
| Bofors RP15 | <<locked>> | 80% | 46,891 psi | 70% | 2953 fps | 99.8% |
| Bofors RP30 | <<locked>> | 80% | 40,437 psi | 61% | 2835 fps | 98.6% |
| Bofors RP5 | <<locked>> | 80% | 50,459 psi | 76% | 3022 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 40,596 psi | 61% | 2835 fps | 99.1% |
| Hodgdon H4831 | <<locked>> | 80% | 51,895 psi | 78% | 3012 fps | 99.6% |
| Hodgdon H4831 SC | <<locked>> | 80% | 51,024 psi | 76% | 2995 fps | 99.5% |
| Hodgdon Retumbo | 81.2 gr | 80% | 42,409 psi | 64% | 2959 fps | 99.9% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,572 psi | 43% | 1811 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 52,214 psi | 78% | 2989 fps | 99.7% |
| IMR 7828 SSC | <<locked>> | 80% | 48,573 psi | 73% | 3005 fps | 99.6% |
| IMR 7977 Enduron | <<locked>> | 86% | 50,923 psi | 76% | 2936 fps | 95.2% |
| IMR 8133 Enduron | <<locked>> | 80% | 32,097 psi | 48% | 2638 fps | 95.5% |
| Lovex D100 | <<locked>> | 92% | 55,724 psi | 84% | 3048 fps | 95.4% |
| Lovex S071 | <<locked>> | 80% | 43,294 psi | 65% | 2799 fps | 100% |
| Norma 217 | <<locked>> | 80% | 32,735 psi | 49% | 2671 fps | 98% |
| Norma MRP | <<locked>> | 80% | 53,983 psi | 81% | 3091 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 49,429 psi | 74% | 3025 fps | 99.8% |
| Ramshot Magnum | <<locked>> | 80% | 44,701 psi | 67% | 2890 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,486 psi | 44% | 1857 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 42,395 psi | 64% | 2936 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 39,001 psi | 58% | 2825 fps | 96.9% |
| Rottweil R 904 | <<locked>> | 80% | 54,563 psi | 82% | 3035 fps | 100% |
| Rottweil R 905 | <<locked>> | 80% | 53,911 psi | 81% | 3048 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 92% | 55,724 psi | 84% | 3048 fps | 95.4% |
| SNPE Vectan SP 13 | <<locked>> | 94% | 45,063 psi | 68% | 2897 fps | 95.9% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 53,563 psi | 80% | 3045 fps | 100% |
| Somchem S361 | <<locked>> | 80% | 55,840 psi | 84% | 3022 fps | 99.9% |
| Somchem S385 | <<locked>> | 80% | 54,172 psi | 81% | 3015 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 47,630 psi | 71% | 2890 fps | 100% |
| Vihtavuori N170 | <<locked>> | 84% | 47,007 psi | 70% | 2907 fps | 95.8% |
| Vihtavuori N555 | <<locked>> | 80% | 53,969 psi | 81% | 3012 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 53,287 psi | 80% | 3094 fps | 99.8% |
| Vihtavuori N565 | <<locked>> | 80% | 44,802 psi | 67% | 2910 fps | 98.9% |
| Vihtavuori N568 | <<locked>> | 80% | 39,943 psi | 60% | 2841 fps | 96.6% |
| Vihtavuori N570 | 88.5 gr | 84% | 44,005 psi | 66% | 2966 fps | 96% |
| Winchester StaBALL HD | <<locked>> | 80% | 49,443 psi | 74% | 3015 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 50,183 psi | 75% | 2949 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 52 powders for 7.21 Firebird loaded with the .284 | 155gr | Frontier PH HPFB. ADI AR 2218 delivers the highest muzzle velocity at 3,274 fps; across all powders the maximum-charge window runs from 2,021 fps to 3,274 fps. Accurate 8700 gives the best case fill at 100 %, and 52 of the 52 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 155.0 gr projectile in 0.284" calls for a 1:9.5 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, Hodgdon Retumbo, Vihtavuori N570 rank at the top here: for 7.21 Firebird with the .284 | 155gr | Frontier PH HPFB 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.