Load Specifications
Load data in caliber 7.21 Firebird with .284 | 136gr | Peregrine VLR-5 bullet and 52 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 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>> | 88% | 59,538 psi | 89% | 3238 fps | 100% |
| Accurate MAGPRO | <<locked>> | 86% | 59,030 psi | 88% | 3363 fps | 99.6% |
| ADI AR 2209 | <<locked>> | 84% | 56,840 psi | 85% | 3278 fps | 100% |
| ADI AR 2213 | <<locked>> | 88% | 59,625 psi | 89% | 3356 fps | 99.9% |
| ADI AR 2217 | <<locked>> | 96% | 58,972 psi | 88% | 3333 fps | 100% |
| ADI AR 2218ᴾ | <<locked>> | 100% | 60,292 psi | 90% | 3474 fps | 99.2% |
| ADI AR 2225 | <<locked>> | 98% | 58,407 psi | 88% | 3353 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 86% | 60,234 psi | 90% | 3327 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 88% | 59,886 psi | 90% | 3346 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 88% | 57,928 psi | 87% | 3241 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 92% | 58,914 psi | 88% | 3323 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 84% | 59,045 psi | 89% | 3337 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 96% | 57,609 psi | 86% | 3366 fps | 98.5% |
| Alliant Reloder-50ᴾ | <<locked>> | 100% | 57,435 psi | 86% | 3346 fps | 98% |
| Baschieri & Pellagri 109 | <<locked>> | 90% | 60,017 psi | 90% | 3310 fps | 98.9% |
| Bofors RP15 | <<locked>> | 90% | 59,234 psi | 89% | 3337 fps | 100% |
| Bofors RP30 | <<locked>> | 94% | 58,566 psi | 88% | 3343 fps | 100% |
| Bofors RP5 | <<locked>> | 88% | 59,886 psi | 90% | 3346 fps | 100% |
| Hodgdon H1000 | <<locked>> | 92% | 56,333 psi | 84% | 3291 fps | 100% |
| Hodgdon H4831 | <<locked>> | 86% | 58,421 psi | 88% | 3284 fps | 99.7% |
| Hodgdon H4831 SC | <<locked>> | 86% | 57,246 psi | 86% | 3264 fps | 99.6% |
| Hodgdon Hybrid 100V | <<locked>> | 82% | 56,956 psi | 85% | 3176 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 92% | 58,421 psi | 88% | 3422 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,739 psi | 57% | 2146 fps | 100% |
| IMR 4350 | <<locked>> | 82% | 58,813 psi | 88% | 3248 fps | 100% |
| IMR 4831 | <<locked>> | 82% | 59,669 psi | 89% | 3248 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 86% | 58,291 psi | 87% | 3258 fps | 99.7% |
| IMR 7828 SSC | <<locked>> | 88% | 58,146 psi | 87% | 3340 fps | 99.9% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 56,855 psi | 85% | 3327 fps | 100% |
| Lovex S071 | <<locked>> | 92% | 57,392 psi | 86% | 3205 fps | 100% |
| Norma 217ᴾ | <<locked>> | 100% | 58,378 psi | 88% | 3350 fps | 100% |
| Norma MRP | <<locked>> | 84% | 56,159 psi | 84% | 3301 fps | 100% |
| Ramshot Grand | <<locked>> | 88% | 59,712 psi | 90% | 3363 fps | 100% |
| Ramshot Magnum | <<locked>> | 90% | 58,146 psi | 87% | 3281 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,595 psi | 58% | 2192 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 92% | 59,944 psi | 90% | 3409 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 94% | 58,885 psi | 88% | 3373 fps | 99.7% |
| Rottweil R 904 | <<locked>> | 84% | 57,072 psi | 86% | 3241 fps | 99.8% |
| Rottweil R 905 | <<locked>> | 86% | 59,988 psi | 90% | 3317 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 86% | 59,596 psi | 89% | 3314 fps | 100% |
| Somchem S361 | <<locked>> | 84% | 58,798 psi | 88% | 3232 fps | 99.7% |
| Somchem S365 | <<locked>> | 82% | 59,350 psi | 89% | 3238 fps | 100% |
| Somchem S385 | <<locked>> | 86% | 60,350 psi | 90% | 3281 fps | 100% |
| Vihtavuori N165 | <<locked>> | 88% | 56,666 psi | 85% | 3205 fps | 100% |
| Vihtavuori N170 | <<locked>> | 94% | 60,075 psi | 90% | 3294 fps | 97.6% |
| Vihtavuori N555 | <<locked>> | 86% | 59,524 psi | 89% | 3271 fps | 100% |
| Vihtavuori N560 | <<locked>> | 86% | 59,741 psi | 90% | 3373 fps | 99.8% |
| Vihtavuori N565 | <<locked>> | 90% | 56,724 psi | 85% | 3294 fps | 99.7% |
| Vihtavuori N568 | <<locked>> | 94% | 58,972 psi | 88% | 3369 fps | 99.5% |
| Vihtavuori N570 | <<locked>> | 94% | 56,318 psi | 84% | 3369 fps | 97.9% |
| Winchester StaBALL HD | <<locked>> | 88% | 59,016 psi | 88% | 3340 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 86% | 56,391 psi | 85% | 3219 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% | 45,107 psi | 68% | 2992 fps | 100% |
| Accurate MAGPRO | <<locked>> | 80% | 47,326 psi | 71% | 3143 fps | 97.8% |
| ADI AR 2209 | <<locked>> | 80% | 49,487 psi | 74% | 3146 fps | 99.6% |
| ADI AR 2213 | <<locked>> | 80% | 44,831 psi | 67% | 3084 fps | 98.2% |
| ADI AR 2217 | <<locked>> | 82% | 35,549 psi | 53% | 2851 fps | 95.7% |
| ADI AR 2218 | <<locked>> | 92% | 44,164 psi | 66% | 3136 fps | 95% |
| ADI AR 2225 | <<locked>> | 80% | 30,371 psi | 46% | 2740 fps | 96.5% |
| Alliant Reloder-19 | <<locked>> | 80% | 49,371 psi | 74% | 3140 fps | 99.6% |
| Alliant Reloder-22 | <<locked>> | 80% | 45,498 psi | 68% | 3087 fps | 99.2% |
| Alliant Reloder-23 | <<locked>> | 80% | 44,106 psi | 66% | 3012 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 38,290 psi | 57% | 2946 fps | 99.8% |
| Alliant Reloder-26 | <<locked>> | 80% | 50,647 psi | 76% | 3202 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 90% | 45,527 psi | 68% | 3130 fps | 95.5% |
| Alliant Reloder-50 | <<locked>> | 96% | 49,153 psi | 74% | 3189 fps | 96.1% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 42,931 psi | 64% | 2982 fps | 95% |
| Bofors RP15 | <<locked>> | 80% | 42,221 psi | 63% | 3012 fps | 98.5% |
| Bofors RP30 | <<locked>> | 80% | 35,679 psi | 53% | 2864 fps | 95.8% |
| Bofors RP5 | <<locked>> | 80% | 45,498 psi | 68% | 3087 fps | 99.2% |
| Hodgdon H1000 | <<locked>> | 80% | 36,143 psi | 54% | 2871 fps | 96.6% |
| Hodgdon H4831 | <<locked>> | 80% | 47,268 psi | 71% | 3084 fps | 98.2% |
| Hodgdon H4831 SC | <<locked>> | 80% | 46,470 psi | 70% | 3068 fps | 98% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 53,258 psi | 80% | 3120 fps | 100% |
| Hodgdon Retumbo | 82.5 gr | 80% | 37,391 psi | 56% | 2992 fps | 98.2% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,311 psi | 42% | 1926 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 55,042 psi | 83% | 3189 fps | 100% |
| IMR 4831 | <<locked>> | 80% | 55,709 psi | 84% | 3189 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 47,964 psi | 72% | 3068 fps | 98.5% |
| IMR 7828 SSC | <<locked>> | 80% | 43,468 psi | 65% | 3061 fps | 97.9% |
| IMR 8133 Enduron | <<locked>> | 86% | 34,606 psi | 52% | 2848 fps | 95.1% |
| Lovex S071 | <<locked>> | 80% | 38,595 psi | 58% | 2854 fps | 99.4% |
| Norma 217 | <<locked>> | 82% | 30,110 psi | 45% | 2733 fps | 95.3% |
| Norma MRP | <<locked>> | 80% | 48,501 psi | 73% | 3163 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 43,859 psi | 66% | 3074 fps | 98.4% |
| Ramshot Magnum | <<locked>> | 80% | 39,450 psi | 59% | 2930 fps | 98.7% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 28,993 psi | 43% | 1972 fps | 100% |
| ReloadSwiss RS 76 | 88.3 gr | 80% | 36,927 psi | 55% | 2963 fps | 99% |
| ReloadSwiss RS 80 | <<locked>> | 84% | 39,711 psi | 60% | 2986 fps | 95.7% |
| Rottweil R 904 | <<locked>> | 80% | 50,053 psi | 75% | 3117 fps | 99.2% |
| Rottweil R 905 | <<locked>> | 80% | 48,878 psi | 73% | 3127 fps | 99.6% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 48,544 psi | 73% | 3120 fps | 99.6% |
| Somchem S361 | <<locked>> | 80% | 51,242 psi | 77% | 3104 fps | 98.9% |
| Somchem S365 | <<locked>> | 80% | 55,288 psi | 83% | 3179 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 49,342 psi | 74% | 3097 fps | 99.9% |
| Vihtavuori N165 | <<locked>> | 80% | 43,149 psi | 65% | 2959 fps | 99.2% |
| Vihtavuori N170 | <<locked>> | 90% | 52,199 psi | 78% | 3153 fps | 95.8% |
| Vihtavuori N555 | <<locked>> | 80% | 48,733 psi | 73% | 3100 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 48,066 psi | 72% | 3159 fps | 98.5% |
| Vihtavuori N565 | <<locked>> | 80% | 39,813 psi | 60% | 2949 fps | 96.5% |
| Vihtavuori N568 | <<locked>> | 84% | 40,727 psi | 61% | 3005 fps | 95.5% |
| Vihtavuori N570 | 96.3 gr | 90% | 48,472 psi | 73% | 3215 fps | 96% |
| Winchester StaBALL HD | <<locked>> | 80% | 43,076 psi | 65% | 3077 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 45,527 psi | 68% | 3018 fps | 99.2% |
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 61 powders for 7.21 Firebird loaded with the .284 | 136gr | Peregrine VLR-5. ADI AR 2218 delivers the highest muzzle velocity at 3,474 fps; across all powders the maximum-charge window runs from 2,146 fps to 3,474 fps. Accurate 8700 gives the best case fill at 100 %, and 61 of the 61 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 136.0 gr projectile in 0.284" calls for a 1:9.5 twist; slower twists will usually not stabilise this weight. Accurate 8700, ADI AR 2218, Alliant Reloder-50 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, ReloadSwiss RS 76 rank at the top here: for 7.21 Firebird with the .284 | 136gr | Peregrine VLR-5 they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Hodgdon 50BMG, Hodgdon US 869, Lovex D100 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.