Load Specifications
Load data in caliber 7.21 Firebird with .284 | 157gr | CutEdge MTAC bullet and 53 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 Hodgdon Retumbo.
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>> | 86% | 60,075 psi | 90% | 3061 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 52,750 psi | 79% | 3054 fps | 98.3% |
| Accurate MAGPRO | <<locked>> | 84% | 59,727 psi | 90% | 3192 fps | 100% |
| ADI AR 2209 | <<locked>> | 82% | 57,246 psi | 86% | 3100 fps | 100% |
| ADI AR 2213 | <<locked>> | 84% | 56,289 psi | 84% | 3120 fps | 100% |
| ADI AR 2217 | <<locked>> | 94% | 60,321 psi | 90% | 3169 fps | 100% |
| ADI AR 2218 | <<locked>> | 96% | 56,913 psi | 85% | 3248 fps | 99.5% |
| ADI AR 2225 | <<locked>> | 96% | 59,988 psi | 90% | 3186 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 82% | 56,884 psi | 85% | 3091 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 84% | 56,724 psi | 85% | 3114 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 86% | 58,769 psi | 88% | 3064 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 90% | 60,162 psi | 90% | 3150 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 82% | 60,133 psi | 90% | 3159 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 94% | 59,030 psi | 88% | 3219 fps | 99.5% |
| Alliant Reloder-50 | <<locked>> | 98% | 59,219 psi | 89% | 3209 fps | 99.2% |
| Baschieri & Pellagri 109 | <<locked>> | 86% | 56,478 psi | 85% | 3084 fps | 99.3% |
| Bofors RP15 | <<locked>> | 88% | 60,176 psi | 90% | 3166 fps | 100% |
| Bofors RP30 | <<locked>> | 92% | 59,915 psi | 90% | 3182 fps | 100% |
| Bofors RP5 | <<locked>> | 84% | 56,724 psi | 85% | 3114 fps | 100% |
| Hodgdon H1000 | <<locked>> | 90% | 57,377 psi | 86% | 3127 fps | 100% |
| Hodgdon H4831 | <<locked>> | 84% | 58,740 psi | 88% | 3110 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 84% | 57,566 psi | 86% | 3094 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 90% | 60,089 psi | 90% | 3255 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,913 psi | 57% | 2008 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 84% | 58,465 psi | 88% | 3081 fps | 100% |
| IMR 7828 SSC | <<locked>> | 86% | 58,958 psi | 88% | 3169 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 90% | 57,406 psi | 86% | 3041 fps | 96.9% |
| IMR 8133 Enduron | <<locked>> | 98% | 58,653 psi | 88% | 3176 fps | 100% |
| Lovex D100 | <<locked>> | 94% | 58,958 psi | 88% | 3094 fps | 96.3% |
| Lovex S071 | <<locked>> | 90% | 58,291 psi | 87% | 3035 fps | 100% |
| Norma 217 | <<locked>> | 98% | 60,263 psi | 90% | 3192 fps | 100% |
| Norma MRP | <<locked>> | 82% | 57,043 psi | 86% | 3127 fps | 100% |
| Ramshot Grand | <<locked>> | 84% | 56,536 psi | 85% | 3133 fps | 100% |
| Ramshot Magnum | <<locked>> | 88% | 59,263 psi | 89% | 3114 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,001 psi | 58% | 2057 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 88% | 56,840 psi | 85% | 3173 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 92% | 60,162 psi | 90% | 3215 fps | 100% |
| Rottweil R 904 | <<locked>> | 82% | 57,377 psi | 86% | 3068 fps | 100% |
| Rottweil R 905 | <<locked>> | 82% | 56,811 psi | 85% | 3081 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 94% | 58,958 psi | 88% | 3094 fps | 96.3% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 54,360 psi | 81% | 3061 fps | 98.2% |
| SNPE Vectan Tubal 8000 | <<locked>> | 84% | 60,365 psi | 90% | 3140 fps | 100% |
| Somchem S361 | <<locked>> | 82% | 58,914 psi | 88% | 3058 fps | 100% |
| Somchem S385 | <<locked>> | 82% | 56,898 psi | 85% | 3045 fps | 100% |
| Vihtavuori N165 | <<locked>> | 86% | 57,145 psi | 86% | 3035 fps | 100% |
| Vihtavuori N170 | <<locked>> | 90% | 56,666 psi | 85% | 3074 fps | 98.1% |
| Vihtavuori N555 | <<locked>> | 82% | 56,579 psi | 85% | 3041 fps | 100% |
| Vihtavuori N560 | <<locked>> | 82% | 56,333 psi | 84% | 3136 fps | 100% |
| Vihtavuori N565 | <<locked>> | 88% | 57,682 psi | 86% | 3130 fps | 100% |
| Vihtavuori N568 | <<locked>> | 92% | 60,307 psi | 90% | 3219 fps | 100% |
| Vihtavuori N570 | <<locked>> | 92% | 57,812 psi | 87% | 3225 fps | 99.1% |
| Winchester StaBALL HD | <<locked>> | 84% | 56,434 psi | 85% | 3107 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 84% | 56,782 psi | 85% | 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% | 49,037 psi | 74% | 2894 fps | 100% |
| Accurate 8700 | <<locked>> | 94% | 41,974 psi | 63% | 2844 fps | 95.4% |
| Accurate MAGPRO | <<locked>> | 80% | 51,866 psi | 78% | 3061 fps | 99.5% |
| ADI AR 2209 | <<locked>> | 80% | 53,476 psi | 80% | 3041 fps | 100% |
| ADI AR 2213 | <<locked>> | 80% | 48,936 psi | 73% | 2995 fps | 99.7% |
| ADI AR 2217 | <<locked>> | 80% | 36,347 psi | 54% | 2723 fps | 97.6% |
| ADI AR 2218 | 94.4 gr | 88% | 41,872 psi | 63% | 2936 fps | 96% |
| ADI AR 2225 | <<locked>> | 80% | 33,576 psi | 50% | 2690 fps | 99.2% |
| Alliant Reloder-19 | <<locked>> | 80% | 53,287 psi | 80% | 3031 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 49,574 psi | 74% | 2992 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 80% | 48,124 psi | 72% | 2904 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 42,308 psi | 63% | 2861 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 80% | 55,724 psi | 84% | 3097 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 84% | 40,234 psi | 60% | 2851 fps | 95.2% |
| Alliant Reloder-50 | <<locked>> | 90% | 43,468 psi | 65% | 2913 fps | 95.8% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 46,369 psi | 70% | 2897 fps | 97.5% |
| Bofors RP15 | <<locked>> | 80% | 46,021 psi | 69% | 2923 fps | 99.8% |
| Bofors RP30 | <<locked>> | 80% | 39,421 psi | 59% | 2802 fps | 98.4% |
| Bofors RP5 | <<locked>> | 80% | 49,574 psi | 74% | 2992 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 39,755 psi | 60% | 2805 fps | 99% |
| Hodgdon H4831 | <<locked>> | 80% | 51,155 psi | 77% | 2986 fps | 99.6% |
| Hodgdon H4831 SC | <<locked>> | 80% | 50,285 psi | 75% | 2972 fps | 99.5% |
| Hodgdon Retumbo | 81 gr | 80% | 41,524 psi | 62% | 2930 fps | 99.9% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,558 psi | 43% | 1801 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 51,387 psi | 77% | 2966 fps | 99.7% |
| IMR 7828 SSC | <<locked>> | 80% | 47,616 psi | 71% | 2976 fps | 99.6% |
| IMR 7977 Enduron | <<locked>> | 86% | 50,299 psi | 75% | 2917 fps | 95.2% |
| IMR 8133 Enduron | <<locked>> | 80% | 31,038 psi | 47% | 2598 fps | 95% |
| Lovex D100 | <<locked>> | 92% | 54,752 psi | 82% | 3022 fps | 95.3% |
| Lovex S071 | <<locked>> | 80% | 42,119 psi | 63% | 2766 fps | 100% |
| Norma 217 | <<locked>> | 80% | 31,589 psi | 47% | 2628 fps | 97.6% |
| Norma MRP | <<locked>> | 80% | 53,084 psi | 80% | 3064 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 48,544 psi | 73% | 2999 fps | 99.8% |
| Ramshot Magnum | <<locked>> | 80% | 43,569 psi | 65% | 2854 fps | 99.9% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,327 psi | 44% | 1844 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 41,278 psi | 62% | 2900 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 37,782 psi | 57% | 2782 fps | 96.5% |
| Rottweil R 904 | <<locked>> | 80% | 53,737 psi | 81% | 3012 fps | 100% |
| Rottweil R 905 | <<locked>> | 80% | 53,069 psi | 80% | 3022 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 92% | 54,752 psi | 82% | 3022 fps | 95.3% |
| SNPE Vectan SP 13 | <<locked>> | 94% | 43,918 psi | 66% | 2864 fps | 95.6% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 52,736 psi | 79% | 3018 fps | 100% |
| Somchem S361 | <<locked>> | 80% | 54,955 psi | 82% | 2999 fps | 99.9% |
| Somchem S385 | <<locked>> | 80% | 53,287 psi | 80% | 2989 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 46,775 psi | 70% | 2864 fps | 100% |
| Vihtavuori N170 | <<locked>> | 84% | 46,050 psi | 69% | 2877 fps | 95.7% |
| Vihtavuori N555 | <<locked>> | 80% | 52,924 psi | 79% | 2986 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 52,489 psi | 79% | 3071 fps | 99.8% |
| Vihtavuori N565 | <<locked>> | 80% | 43,758 psi | 66% | 2881 fps | 98.8% |
| Vihtavuori N568 | <<locked>> | 80% | 38,812 psi | 58% | 2805 fps | 96.3% |
| Vihtavuori N570 | 88.3 gr | 84% | 43,018 psi | 64% | 2933 fps | 95.7% |
| Winchester StaBALL HD | <<locked>> | 80% | 48,356 psi | 72% | 2986 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 49,371 psi | 74% | 2923 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 53 powders for 7.21 Firebird loaded with the .284 | 157gr | CutEdge MTAC. Hodgdon Retumbo delivers the highest muzzle velocity at 3,255 fps; across all powders the maximum-charge window runs from 2,008 fps to 3,255 fps. Accurate 8700 gives the best case fill at 100 %, and 53 of the 53 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 157.0 gr projectile in 0.284" calls for a 1:9.0 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, Hodgdon Retumbo rank at the top here: for 7.21 Firebird with the .284 | 157gr | CutEdge MTAC 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.