Load Specifications
Load data in caliber 7.21 Firebird with .284 | 145gr | Peregrine Glider GRM bullet and 53 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Vihtavuori N570, Hodgdon Retumbo and ADI AR 2218.
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% | 56,652 psi | 85% | 3114 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 48,588 psi | 73% | 3068 fps | 96.6% |
| Accurate MAGPRO | <<locked>> | 86% | 60,336 psi | 90% | 3304 fps | 99.9% |
| ADI AR 2209 | <<locked>> | 84% | 58,059 psi | 87% | 3215 fps | 100% |
| ADI AR 2213 | <<locked>> | 86% | 56,869 psi | 85% | 3232 fps | 99.9% |
| ADI AR 2217 | <<locked>> | 96% | 60,321 psi | 90% | 3274 fps | 100% |
| ADI AR 2218 | <<locked>> | 98% | 57,029 psi | 85% | 3343 fps | 99.1% |
| ADI AR 2225 | <<locked>> | 98% | 59,756 psi | 90% | 3291 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 84% | 57,464 psi | 86% | 3199 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 86% | 57,261 psi | 86% | 3225 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 88% | 59,132 psi | 89% | 3176 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 92% | 60,292 psi | 90% | 3261 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 82% | 56,115 psi | 84% | 3212 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 96% | 58,972 psi | 88% | 3314 fps | 99% |
| Alliant Reloder-50ᴾ | <<locked>> | 100% | 59,016 psi | 88% | 3301 fps | 98.7% |
| Baschieri & Pellagri 109 | <<locked>> | 88% | 57,174 psi | 86% | 3189 fps | 98.9% |
| Bofors RP15 | <<locked>> | 88% | 56,652 psi | 85% | 3215 fps | 100% |
| Bofors RP30 | <<locked>> | 94% | 60,017 psi | 90% | 3287 fps | 100% |
| Bofors RP5 | <<locked>> | 86% | 57,261 psi | 86% | 3225 fps | 100% |
| Hodgdon H1000 | <<locked>> | 92% | 57,740 psi | 87% | 3232 fps | 100% |
| Hodgdon H4831 | <<locked>> | 86% | 59,379 psi | 89% | 3222 fps | 99.9% |
| Hodgdon H4831 SC | <<locked>> | 86% | 58,392 psi | 88% | 3205 fps | 99.9% |
| Hodgdon Hybrid 100V | <<locked>> | 82% | 57,957 psi | 87% | 3107 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 92% | 60,017 psi | 90% | 3363 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,739 psi | 57% | 2077 fps | 100% |
| IMR 4350 | <<locked>> | 82% | 59,843 psi | 90% | 3182 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 86% | 59,466 psi | 89% | 3196 fps | 99.9% |
| IMR 7828 SSC | <<locked>> | 88% | 59,306 psi | 89% | 3278 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 92% | 58,030 psi | 87% | 3140 fps | 96.1% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 58,334 psi | 87% | 3271 fps | 100% |
| Lovex S071 | <<locked>> | 92% | 58,610 psi | 88% | 3140 fps | 100% |
| Norma 217ᴾ | <<locked>> | 100% | 59,973 psi | 90% | 3294 fps | 100% |
| Norma MRP | <<locked>> | 84% | 57,450 psi | 86% | 3238 fps | 100% |
| Ramshot Grand | <<locked>> | 86% | 56,652 psi | 85% | 3235 fps | 100% |
| Ramshot Magnum | <<locked>> | 90% | 59,654 psi | 89% | 3222 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,783 psi | 58% | 2126 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 90% | 56,681 psi | 85% | 3281 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 92% | 55,840 psi | 84% | 3245 fps | 99.7% |
| Rottweil R 904 | <<locked>> | 84% | 58,175 psi | 87% | 3179 fps | 100% |
| Rottweil R 905 | <<locked>> | 84% | 57,334 psi | 86% | 3196 fps | 100% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 50,647 psi | 76% | 3084 fps | 96.7% |
| SNPE Vectan Tubal 8000 | <<locked>> | 84% | 56,956 psi | 85% | 3189 fps | 100% |
| Somchem S361 | <<locked>> | 84% | 59,799 psi | 90% | 3169 fps | 99.9% |
| Somchem S385 | <<locked>> | 84% | 57,421 psi | 86% | 3153 fps | 100% |
| Vihtavuori N165 | <<locked>> | 88% | 57,682 psi | 86% | 3143 fps | 100% |
| Vihtavuori N170 | <<locked>> | 92% | 57,246 psi | 86% | 3173 fps | 97.5% |
| Vihtavuori N555 | <<locked>> | 84% | 56,942 psi | 85% | 3153 fps | 100% |
| Vihtavuori N560 | <<locked>> | 84% | 56,797 psi | 85% | 3245 fps | 99.8% |
| Vihtavuori N565 | <<locked>> | 90% | 58,001 psi | 87% | 3238 fps | 99.9% |
| Vihtavuori N568 | <<locked>> | 92% | 56,231 psi | 84% | 3251 fps | 99.5% |
| Vihtavuori N570 | <<locked>> | 94% | 57,812 psi | 87% | 3320 fps | 98.6% |
| Winchester StaBALL HD | <<locked>> | 86% | 56,072 psi | 84% | 3212 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 86% | 57,551 psi | 86% | 3156 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% | 46,035 psi | 69% | 2936 fps | 100% |
| Accurate 8700 | <<locked>> | 98% | 45,121 psi | 68% | 2995 fps | 95.5% |
| Accurate MAGPRO | <<locked>> | 80% | 48,530 psi | 73% | 3094 fps | 98.5% |
| ADI AR 2209 | <<locked>> | 80% | 50,633 psi | 76% | 3091 fps | 99.9% |
| ADI AR 2213 | <<locked>> | 80% | 45,847 psi | 69% | 3031 fps | 98.8% |
| ADI AR 2217 | <<locked>> | 80% | 33,852 psi | 51% | 2740 fps | 95.6% |
| ADI AR 2218 | 98.4 gr | 92% | 45,295 psi | 68% | 3100 fps | 96.2% |
| ADI AR 2225 | <<locked>> | 80% | 31,140 psi | 47% | 2703 fps | 97.6% |
| Alliant Reloder-19 | <<locked>> | 80% | 50,328 psi | 75% | 3077 fps | 99.9% |
| Alliant Reloder-22 | <<locked>> | 80% | 46,499 psi | 70% | 3031 fps | 99.6% |
| Alliant Reloder-23 | <<locked>> | 80% | 45,208 psi | 68% | 2956 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 39,407 psi | 59% | 2897 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 80% | 51,909 psi | 78% | 3143 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 88% | 43,279 psi | 65% | 3009 fps | 95.4% |
| Alliant Reloder-50 | <<locked>> | 94% | 46,775 psi | 70% | 3071 fps | 96% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 43,845 psi | 66% | 2933 fps | 95.9% |
| Bofors RP15 | <<locked>> | 80% | 43,120 psi | 65% | 2959 fps | 99% |
| Bofors RP30 | <<locked>> | 80% | 36,593 psi | 55% | 2822 fps | 96.8% |
| Bofors RP5 | <<locked>> | 80% | 46,499 psi | 70% | 3031 fps | 99.6% |
| Hodgdon H1000 | <<locked>> | 80% | 37,028 psi | 56% | 2828 fps | 97.6% |
| Hodgdon H4831 | <<locked>> | 80% | 48,240 psi | 72% | 3028 fps | 98.8% |
| Hodgdon H4831 SC | <<locked>> | 80% | 47,413 psi | 71% | 3012 fps | 98.6% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 54,331 psi | 81% | 3054 fps | 100% |
| Hodgdon Retumbo | 80.7 gr | 80% | 38,363 psi | 57% | 2949 fps | 98.9% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,384 psi | 43% | 1867 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 56,115 psi | 84% | 3123 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 48,921 psi | 73% | 3015 fps | 99% |
| IMR 7828 SSC | <<locked>> | 80% | 44,628 psi | 67% | 3012 fps | 98.6% |
| IMR 7977 Enduron | <<locked>> | 90% | 54,491 psi | 82% | 3077 fps | 95.3% |
| IMR 8133 Enduron | <<locked>> | 84% | 33,141 psi | 50% | 2743 fps | 95.1% |
| Lovex S071 | <<locked>> | 80% | 39,450 psi | 59% | 2805 fps | 99.7% |
| Norma 217 | <<locked>> | 80% | 28,863 psi | 43% | 2631 fps | 95.3% |
| Norma MRP | <<locked>> | 80% | 49,719 psi | 75% | 3107 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 45,063 psi | 68% | 3025 fps | 99% |
| Ramshot Magnum | <<locked>> | 80% | 40,567 psi | 61% | 2887 fps | 99.3% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,095 psi | 44% | 1909 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 37,956 psi | 57% | 2920 fps | 99.5% |
| ReloadSwiss RS 80 | <<locked>> | 82% | 37,695 psi | 56% | 2871 fps | 95.6% |
| Rottweil R 904 | <<locked>> | 80% | 51,082 psi | 77% | 3061 fps | 99.5% |
| Rottweil R 905 | <<locked>> | 80% | 50,024 psi | 75% | 3068 fps | 99.9% |
| SNPE Vectan SP 13 | <<locked>> | 98% | 47,079 psi | 71% | 3015 fps | 95.7% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 49,676 psi | 74% | 3064 fps | 99.9% |
| Somchem S361 | <<locked>> | 80% | 52,127 psi | 78% | 3045 fps | 99.3% |
| Somchem S385 | <<locked>> | 80% | 50,299 psi | 75% | 3038 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 44,034 psi | 66% | 2907 fps | 99.5% |
| Vihtavuori N170 | <<locked>> | 88% | 49,792 psi | 75% | 3038 fps | 95.8% |
| Vihtavuori N555 | <<locked>> | 80% | 49,705 psi | 75% | 3038 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 49,211 psi | 74% | 3107 fps | 99% |
| Vihtavuori N565 | <<locked>> | 80% | 40,828 psi | 61% | 2904 fps | 97.4% |
| Vihtavuori N568 | <<locked>> | 82% | 38,711 psi | 58% | 2890 fps | 95.3% |
| Vihtavuori N570 | 92.2 gr | 88% | 46,238 psi | 69% | 3097 fps | 95.9% |
| Winchester StaBALL HD | <<locked>> | 80% | 44,425 psi | 67% | 3022 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 46,485 psi | 70% | 2966 fps | 99.6% |
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 | 145gr | Peregrine Glider GRM. Hodgdon Retumbo delivers the highest muzzle velocity at 3,363 fps; across all powders the maximum-charge window runs from 2,077 fps to 3,363 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 145.0 gr projectile in 0.284" calls for a 1:8.5 twist; slower twists will usually not stabilise this weight. Accurate 8700, Alliant Reloder-50, Hodgdon TrailBoss 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. Vihtavuori N570, Hodgdon Retumbo, ADI AR 2218 rank at the top here: for 7.21 Firebird with the .284 | 145gr | Peregrine Glider GRM 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.