Load Specifications
Load data in caliber 7.21 Firebird with .284 | 166gr | Peregrine VRG-2 bullet and 51 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are ADI AR 2218, Ramshot LRT 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% | 59,799 psi | 90% | 2986 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 57,551 psi | 86% | 3064 fps | 99.4% |
| Accurate MAGPRO | <<locked>> | 82% | 59,640 psi | 89% | 3117 fps | 100% |
| ADI AR 2213 | <<locked>> | 84% | 60,249 psi | 90% | 3110 fps | 100% |
| ADI AR 2217 | <<locked>> | 92% | 60,321 psi | 90% | 3097 fps | 100% |
| ADI AR 2218 | <<locked>> | 94% | 57,319 psi | 86% | 3186 fps | 99.8% |
| ADI AR 2225 | <<locked>> | 92% | 56,536 psi | 85% | 3061 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 82% | 56,623 psi | 85% | 3038 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 84% | 58,697 psi | 88% | 2986 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 88% | 60,191 psi | 90% | 3074 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 92% | 59,408 psi | 89% | 3153 fps | 99.8% |
| Alliant Reloder-50 | <<locked>> | 96% | 59,901 psi | 90% | 3150 fps | 99.6% |
| Baschieri & Pellagri 109 | <<locked>> | 86% | 59,886 psi | 90% | 3071 fps | 99.8% |
| Bofors RP15 | <<locked>> | 86% | 59,973 psi | 90% | 3087 fps | 100% |
| Bofors RP30 | <<locked>> | 90% | 60,089 psi | 90% | 3110 fps | 100% |
| Bofors RP5 | <<locked>> | 82% | 56,623 psi | 85% | 3038 fps | 100% |
| Hodgdon H1000 | <<locked>> | 88% | 57,493 psi | 86% | 3051 fps | 100% |
| Hodgdon H4831 | <<locked>> | 82% | 58,146 psi | 87% | 3031 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 82% | 57,203 psi | 86% | 3018 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 86% | 56,594 psi | 85% | 3123 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,087 psi | 57% | 1969 fps | 100% |
| Hodgdon US 869 | <<locked>> | 98% | 57,856 psi | 87% | 3064 fps | 96.4% |
| IMR 4955 Enduron | <<locked>> | 82% | 57,943 psi | 87% | 3005 fps | 100% |
| IMR 7828 SSC | <<locked>> | 84% | 58,885 psi | 88% | 3094 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 88% | 56,884 psi | 85% | 2972 fps | 97.5% |
| IMR 8133 Enduron | <<locked>> | 96% | 59,088 psi | 89% | 3107 fps | 100% |
| Lovex D100 | <<locked>> | 92% | 58,726 psi | 88% | 3028 fps | 97% |
| Lovex S071 | <<locked>> | 88% | 58,247 psi | 87% | 2966 fps | 100% |
| Norma 217 | <<locked>> | 94% | 57,087 psi | 86% | 3068 fps | 100% |
| Ramshot Grand | <<locked>> | 82% | 56,463 psi | 85% | 3058 fps | 100% |
| Ramshot LRT | <<locked>> | 94% | 56,652 psi | 85% | 3104 fps | 96.2% |
| Ramshot Magnum | <<locked>> | 86% | 59,088 psi | 89% | 3038 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,189 psi | 59% | 2014 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 86% | 57,232 psi | 86% | 3100 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 88% | 56,028 psi | 84% | 3077 fps | 100% |
| Rottweil R 905 | <<locked>> | 82% | 60,249 psi | 90% | 3061 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 92% | 58,726 psi | 88% | 3028 fps | 97% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 58,871 psi | 88% | 3071 fps | 99.3% |
| SNPE Vectan Tubal 8000 | <<locked>> | 82% | 59,886 psi | 90% | 3058 fps | 100% |
| Somchem S385 | <<locked>> | 82% | 60,321 psi | 90% | 3022 fps | 100% |
| Vihtavuori 20N29ᴾ | <<locked>> | 100% | 52,069 psi | 78% | 2976 fps | 97% |
| Vihtavuori 24N41 | <<locked>> | 96% | 58,682 psi | 88% | 3081 fps | 96.5% |
| Vihtavuori N165 | <<locked>> | 84% | 56,840 psi | 85% | 2963 fps | 100% |
| Vihtavuori N170 | <<locked>> | 90% | 60,365 psi | 90% | 3068 fps | 99.1% |
| Vihtavuori N555 | <<locked>> | 82% | 60,176 psi | 90% | 3015 fps | 100% |
| Vihtavuori N560 | <<locked>> | 82% | 60,104 psi | 90% | 3123 fps | 100% |
| Vihtavuori N565 | <<locked>> | 86% | 57,812 psi | 87% | 3061 fps | 100% |
| Vihtavuori N568 | <<locked>> | 88% | 56,420 psi | 85% | 3081 fps | 99.9% |
| Vihtavuori N570 | <<locked>> | 90% | 58,189 psi | 87% | 3156 fps | 99.5% |
| Winchester StaBALL HD | <<locked>> | 82% | 56,797 psi | 85% | 3031 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 82% | 56,405 psi | 85% | 2969 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% | 52,257 psi | 78% | 2877 fps | 100% |
| Accurate 8700 | <<locked>> | 90% | 39,392 psi | 59% | 2723 fps | 95.2% |
| Accurate MAGPRO | <<locked>> | 80% | 55,521 psi | 83% | 3051 fps | 99.9% |
| ADI AR 2213 | <<locked>> | 80% | 52,286 psi | 78% | 2986 fps | 100% |
| ADI AR 2217 | <<locked>> | 80% | 39,218 psi | 59% | 2730 fps | 99% |
| ADI AR 2218 | 92.3 gr | 84% | 39,131 psi | 59% | 2805 fps | 95.7% |
| ADI AR 2225 | <<locked>> | 80% | 36,492 psi | 55% | 2697 fps | 99.9% |
| Alliant Reloder-22 | <<locked>> | 80% | 52,895 psi | 79% | 2979 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 80% | 51,488 psi | 77% | 2884 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 45,643 psi | 68% | 2848 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 82% | 40,582 psi | 61% | 2795 fps | 96.1% |
| Alliant Reloder-50 | <<locked>> | 86% | 40,959 psi | 61% | 2792 fps | 95.6% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 49,168 psi | 74% | 2890 fps | 98.6% |
| Bofors RP15 | <<locked>> | 80% | 49,168 psi | 74% | 2913 fps | 100% |
| Bofors RP30 | <<locked>> | 80% | 42,569 psi | 64% | 2802 fps | 99.4% |
| Bofors RP5 | <<locked>> | 80% | 52,895 psi | 79% | 2979 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 42,917 psi | 64% | 2805 fps | 99.8% |
| Hodgdon H4831 | <<locked>> | 80% | 54,273 psi | 81% | 2972 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 80% | 53,403 psi | 80% | 2959 fps | 99.9% |
| Hodgdon Retumbo | <<locked>> | 80% | 45,223 psi | 68% | 2930 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,660 psi | 43% | 1765 fps | 100% |
| Hodgdon US 869 | <<locked>> | 96% | 53,838 psi | 81% | 2995 fps | 95.4% |
| IMR 4955 Enduron | <<locked>> | 80% | 54,244 psi | 81% | 2946 fps | 100% |
| IMR 7828 SSC | <<locked>> | 80% | 51,024 psi | 76% | 2969 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 82% | 46,557 psi | 70% | 2789 fps | 95% |
| IMR 8133 Enduron | <<locked>> | 80% | 33,881 psi | 51% | 2612 fps | 97.1% |
| Lovex D100 | <<locked>> | 88% | 50,705 psi | 76% | 2894 fps | 95.1% |
| Lovex S071 | <<locked>> | 80% | 44,962 psi | 67% | 2753 fps | 100% |
| Norma 217 | <<locked>> | 80% | 34,519 psi | 52% | 2638 fps | 99.1% |
| Ramshot Grand | <<locked>> | 80% | 52,417 psi | 79% | 2992 fps | 100% |
| Ramshot LRT | 100.8 gr | 92% | 52,634 psi | 79% | 3035 fps | 95.2% |
| Ramshot Magnum | <<locked>> | 80% | 47,210 psi | 71% | 2854 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,443 psi | 44% | 1804 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 45,295 psi | 68% | 2907 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 41,263 psi | 62% | 2799 fps | 98.3% |
| Rottweil R 905 | <<locked>> | 80% | 56,434 psi | 85% | 3005 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 88% | 50,705 psi | 76% | 2894 fps | 95.1% |
| SNPE Vectan SP 13 | <<locked>> | 90% | 41,365 psi | 62% | 2746 fps | 95.5% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 56,086 psi | 84% | 3002 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 56,449 psi | 85% | 2966 fps | 100% |
| Vihtavuori 20N29 | <<locked>> | 96% | 44,976 psi | 67% | 2838 fps | 95% |
| Vihtavuori 24N41 | <<locked>> | 94% | 54,534 psi | 82% | 3009 fps | 95.5% |
| Vihtavuori N165 | <<locked>> | 80% | 49,748 psi | 75% | 2851 fps | 100% |
| Vihtavuori N170 | <<locked>> | 80% | 42,859 psi | 64% | 2749 fps | 95.4% |
| Vihtavuori N555 | <<locked>> | 80% | 56,434 psi | 85% | 2963 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 56,115 psi | 84% | 3061 fps | 100% |
| Vihtavuori N565 | <<locked>> | 80% | 46,891 psi | 70% | 2874 fps | 99.6% |
| Vihtavuori N568 | <<locked>> | 80% | 42,090 psi | 63% | 2812 fps | 98% |
| Vihtavuori N570 | 86.1 gr | 80% | 40,306 psi | 60% | 2805 fps | 95.5% |
| Winchester StaBALL HD | <<locked>> | 80% | 52,721 psi | 79% | 2969 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 52,634 psi | 79% | 2910 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 51 powders for 7.21 Firebird loaded with the .284 | 166gr | Peregrine VRG-2. ADI AR 2218 delivers the highest muzzle velocity at 3,186 fps; across all powders the maximum-charge window runs from 1,969 fps to 3,186 fps. Accurate 8700 gives the best case fill at 100 %, and 51 of the 51 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 166.0 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, Ramshot LRT, Vihtavuori N570 rank at the top here: for 7.21 Firebird with the .284 | 166gr | Peregrine VRG-2 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.