Load Specifications
Load data in caliber 7.21 Firebird with .284 | 161gr | Peregrine VLR-4 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 ReloadSwiss RS 76.
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% | 56,507 psi | 85% | 2979 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 52,968 psi | 79% | 3031 fps | 98.5% |
| Accurate MAGPRO | <<locked>> | 84% | 60,002 psi | 90% | 3163 fps | 100% |
| ADI AR 2209 | <<locked>> | 82% | 57,508 psi | 86% | 3071 fps | 100% |
| ADI AR 2213 | <<locked>> | 84% | 56,637 psi | 85% | 3094 fps | 100% |
| ADI AR 2217 | <<locked>> | 92% | 56,260 psi | 84% | 3081 fps | 100% |
| ADI AR 2218 | <<locked>> | 96% | 57,116 psi | 86% | 3222 fps | 99.7% |
| ADI AR 2225 | <<locked>> | 96% | 60,249 psi | 90% | 3159 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 82% | 57,159 psi | 86% | 3061 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 84% | 57,087 psi | 86% | 3087 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 86% | 59,117 psi | 89% | 3035 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 88% | 56,449 psi | 85% | 3068 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 94% | 59,422 psi | 89% | 3196 fps | 99.6% |
| Alliant Reloder-50 | <<locked>> | 98% | 59,509 psi | 89% | 3186 fps | 99.4% |
| Baschieri & Pellagri 109 | <<locked>> | 86% | 56,739 psi | 85% | 3054 fps | 99.4% |
| Bofors RP15 | <<locked>> | 86% | 56,492 psi | 85% | 3077 fps | 100% |
| Bofors RP30 | <<locked>> | 92% | 60,075 psi | 90% | 3150 fps | 100% |
| Bofors RP5 | <<locked>> | 84% | 57,087 psi | 86% | 3087 fps | 100% |
| Hodgdon H1000 | <<locked>> | 90% | 57,696 psi | 86% | 3097 fps | 100% |
| Hodgdon H4831 | <<locked>> | 84% | 58,885 psi | 88% | 3084 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 84% | 57,899 psi | 87% | 3068 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 88% | 56,246 psi | 84% | 3166 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,942 psi | 57% | 1982 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 84% | 58,740 psi | 88% | 3054 fps | 100% |
| IMR 7828 SSC | <<locked>> | 86% | 59,190 psi | 89% | 3140 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 90% | 57,609 psi | 86% | 3015 fps | 97.1% |
| IMR 8133 Enduron | <<locked>> | 98% | 58,885 psi | 88% | 3150 fps | 100% |
| Lovex D100 | <<locked>> | 94% | 59,088 psi | 89% | 3064 fps | 96.5% |
| Lovex S071 | <<locked>> | 90% | 58,668 psi | 88% | 3009 fps | 100% |
| Norma 217 | <<locked>> | 96% | 56,608 psi | 85% | 3110 fps | 100% |
| Norma MRP | <<locked>> | 82% | 57,232 psi | 86% | 3097 fps | 100% |
| Ramshot Grand | <<locked>> | 84% | 56,797 psi | 85% | 3104 fps | 100% |
| Ramshot Magnum | <<locked>> | 88% | 59,408 psi | 89% | 3084 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,059 psi | 59% | 2031 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 88% | 57,101 psi | 86% | 3146 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 90% | 55,985 psi | 84% | 3117 fps | 99.9% |
| Rottweil R 904 | <<locked>> | 82% | 57,609 psi | 86% | 3041 fps | 100% |
| Rottweil R 905 | <<locked>> | 82% | 57,072 psi | 86% | 3054 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 94% | 59,088 psi | 89% | 3064 fps | 96.5% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 54,723 psi | 82% | 3038 fps | 98.4% |
| SNPE Vectan Tubal 8000 | <<locked>> | 82% | 56,710 psi | 85% | 3051 fps | 100% |
| Somchem S361 | <<locked>> | 82% | 59,088 psi | 89% | 3028 fps | 100% |
| Somchem S385 | <<locked>> | 82% | 57,159 psi | 86% | 3015 fps | 100% |
| Vihtavuori N165 | <<locked>> | 86% | 57,508 psi | 86% | 3009 fps | 100% |
| Vihtavuori N170 | <<locked>> | 90% | 56,811 psi | 85% | 3045 fps | 98.3% |
| Vihtavuori N555 | <<locked>> | 82% | 56,840 psi | 85% | 3012 fps | 100% |
| Vihtavuori N560 | <<locked>> | 82% | 56,521 psi | 85% | 3110 fps | 100% |
| Vihtavuori N565 | <<locked>> | 88% | 57,943 psi | 87% | 3104 fps | 100% |
| Vihtavuori N568 | <<locked>> | 90% | 56,333 psi | 84% | 3123 fps | 99.8% |
| Vihtavuori N570 | <<locked>> | 92% | 58,044 psi | 87% | 3196 fps | 99.2% |
| Winchester StaBALL HD | <<locked>> | 84% | 56,724 psi | 85% | 3077 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 84% | 57,145 psi | 86% | 3018 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% | 49,240 psi | 74% | 2867 fps | 100% |
| Accurate 8700 | <<locked>> | 94% | 42,221 psi | 63% | 2825 fps | 95.7% |
| Accurate MAGPRO | <<locked>> | 80% | 52,025 psi | 78% | 3035 fps | 99.6% |
| ADI AR 2209 | <<locked>> | 80% | 53,853 psi | 81% | 3015 fps | 100% |
| ADI AR 2213 | <<locked>> | 80% | 49,197 psi | 74% | 2969 fps | 99.8% |
| ADI AR 2217 | <<locked>> | 80% | 36,506 psi | 55% | 2700 fps | 97.9% |
| ADI AR 2218 | 91.1 gr | 86% | 38,986 psi | 58% | 2835 fps | 95% |
| ADI AR 2225 | <<locked>> | 80% | 33,779 psi | 51% | 2671 fps | 99.4% |
| Alliant Reloder-19 | <<locked>> | 80% | 53,490 psi | 80% | 3002 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 49,806 psi | 75% | 2966 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 80% | 48,472 psi | 73% | 2877 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 42,685 psi | 64% | 2838 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 84% | 40,495 psi | 61% | 2831 fps | 95.6% |
| Alliant Reloder-50 | <<locked>> | 88% | 40,553 psi | 61% | 2822 fps | 95% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 46,485 psi | 70% | 2871 fps | 97.7% |
| Bofors RP15 | <<locked>> | 80% | 46,209 psi | 69% | 2900 fps | 99.9% |
| Bofors RP30 | <<locked>> | 80% | 39,653 psi | 59% | 2779 fps | 98.6% |
| Bofors RP5 | <<locked>> | 80% | 49,806 psi | 75% | 2966 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 39,972 psi | 60% | 2782 fps | 99.2% |
| Hodgdon H4831 | <<locked>> | 80% | 51,401 psi | 77% | 2959 fps | 99.7% |
| Hodgdon H4831 SC | <<locked>> | 80% | 50,517 psi | 76% | 2946 fps | 99.6% |
| Hodgdon Retumbo | 80 gr | 80% | 41,785 psi | 63% | 2907 fps | 99.9% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,500 psi | 43% | 1775 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 51,735 psi | 78% | 2940 fps | 99.8% |
| IMR 7828 SSC | <<locked>> | 80% | 47,848 psi | 72% | 2949 fps | 99.7% |
| IMR 7977 Enduron | <<locked>> | 86% | 50,401 psi | 76% | 2890 fps | 95.5% |
| IMR 8133 Enduron | <<locked>> | 80% | 31,328 psi | 47% | 2582 fps | 95.5% |
| Lovex D100 | <<locked>> | 92% | 55,013 psi | 82% | 2999 fps | 95.6% |
| Lovex S071 | <<locked>> | 80% | 42,380 psi | 64% | 2743 fps | 100% |
| Norma 217 | <<locked>> | 80% | 31,778 psi | 48% | 2608 fps | 97.9% |
| Norma MRP | <<locked>> | 80% | 53,432 psi | 80% | 3038 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 48,863 psi | 73% | 2972 fps | 99.9% |
| Ramshot Magnum | <<locked>> | 80% | 43,874 psi | 66% | 2831 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,254 psi | 44% | 1818 fps | 100% |
| ReloadSwiss RS 76 | 85.7 gr | 80% | 41,626 psi | 62% | 2881 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 37,971 psi | 57% | 2762 fps | 96.9% |
| Rottweil R 904 | <<locked>> | 80% | 54,085 psi | 81% | 2982 fps | 100% |
| Rottweil R 905 | <<locked>> | 80% | 53,301 psi | 80% | 2995 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 92% | 55,013 psi | 82% | 2999 fps | 95.6% |
| SNPE Vectan SP 13 | <<locked>> | 94% | 44,266 psi | 66% | 2844 fps | 96% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 52,968 psi | 79% | 2992 fps | 100% |
| Somchem S361 | <<locked>> | 80% | 55,259 psi | 83% | 2972 fps | 99.9% |
| Somchem S385 | <<locked>> | 80% | 53,519 psi | 80% | 2963 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 46,992 psi | 70% | 2841 fps | 100% |
| Vihtavuori N170 | <<locked>> | 84% | 46,253 psi | 69% | 2854 fps | 96% |
| Vihtavuori N555 | <<locked>> | 80% | 53,142 psi | 80% | 2956 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 52,794 psi | 79% | 3045 fps | 99.9% |
| Vihtavuori N565 | <<locked>> | 80% | 43,990 psi | 66% | 2858 fps | 99% |
| Vihtavuori N568 | <<locked>> | 80% | 39,088 psi | 59% | 2785 fps | 96.7% |
| Vihtavuori N570 | <<locked>> | 84% | 43,265 psi | 65% | 2913 fps | 96.1% |
| Winchester StaBALL HD | <<locked>> | 80% | 48,704 psi | 73% | 2959 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 49,617 psi | 74% | 2900 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 57 powders for 7.21 Firebird loaded with the .284 | 161gr | Peregrine VLR-4. ADI AR 2218 delivers the highest muzzle velocity at 3,222 fps; across all powders the maximum-charge window runs from 1,982 fps to 3,222 fps. Accurate 8700 gives the best case fill at 100 %, and 57 of the 57 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 161.0 gr projectile in 0.284" calls for a 1:8.5 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, Hodgdon Retumbo, ReloadSwiss RS 76 rank at the top here: for 7.21 Firebird with the .284 | 161gr | Peregrine VLR-4 they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Hodgdon 50BMG burn incompletely and react more sensitively to barrel length and temperature. Always begin at the start load and work up in small increments while checking case and primer for pressure signs.