Load Specifications
Load data in caliber 7.21 Firebird with .284 | 130gr | Sierra HPBT MatchKing bullet and 51 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.
A valid access license is required to use the Personalized Load Calculator.
You can find more information in our FAQ: How can I use the Personalized Load Calculator?
Max Load - Barrel Length: 26"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 3100 | <<locked>> | 86% | 56,840 psi | 85% | 3248 fps | 100% |
| Accurate MAGPRO | <<locked>> | 86% | 60,162 psi | 90% | 3432 fps | 99.6% |
| ADI AR 2209 | <<locked>> | 84% | 57,682 psi | 86% | 3346 fps | 100% |
| ADI AR 2213 | <<locked>> | 86% | 56,376 psi | 85% | 3356 fps | 99.7% |
| ADI AR 2217 | <<locked>> | 96% | 60,017 psi | 90% | 3399 fps | 100% |
| ADI AR 2218 | <<locked>> | 98% | 56,869 psi | 85% | 3461 fps | 98.4% |
| ADI AR 2225 | <<locked>> | 98% | 59,408 psi | 89% | 3419 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 84% | 57,305 psi | 86% | 3330 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 86% | 56,898 psi | 85% | 3350 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 88% | 59,030 psi | 88% | 3314 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 92% | 59,785 psi | 90% | 3392 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 84% | 60,321 psi | 90% | 3409 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 96% | 58,958 psi | 88% | 3432 fps | 98.5% |
| Alliant Reloder-50ᴾ | <<locked>> | 100% | 59,161 psi | 89% | 3422 fps | 98.1% |
| Baschieri & Pellagri 109 | <<locked>> | 88% | 56,956 psi | 85% | 3310 fps | 98.3% |
| Bofors RP15 | <<locked>> | 90% | 60,191 psi | 90% | 3402 fps | 100% |
| Bofors RP30 | <<locked>> | 94% | 59,857 psi | 90% | 3412 fps | 100% |
| Bofors RP5 | <<locked>> | 86% | 56,898 psi | 85% | 3350 fps | 100% |
| Hodgdon H1000 | <<locked>> | 92% | 57,261 psi | 86% | 3356 fps | 100% |
| Hodgdon H4831 | <<locked>> | 86% | 59,059 psi | 89% | 3346 fps | 99.6% |
| Hodgdon H4831 SC | <<locked>> | 86% | 57,957 psi | 87% | 3330 fps | 99.5% |
| Hodgdon Hybrid 100V | <<locked>> | 82% | 57,812 psi | 87% | 3241 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 92% | 59,437 psi | 89% | 3494 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,826 psi | 57% | 2198 fps | 100% |
| IMR 4350 | <<locked>> | 82% | 59,451 psi | 89% | 3314 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 86% | 59,161 psi | 89% | 3323 fps | 99.7% |
| IMR 7828 SSC | <<locked>> | 88% | 59,016 psi | 88% | 3409 fps | 99.9% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 58,247 psi | 87% | 3396 fps | 99.9% |
| Lovex S071 | <<locked>> | 92% | 58,711 psi | 88% | 3274 fps | 100% |
| Norma 217ᴾ | <<locked>> | 100% | 59,843 psi | 90% | 3422 fps | 100% |
| Norma MRP | <<locked>> | 84% | 57,217 psi | 86% | 3369 fps | 100% |
| Ramshot Grand | <<locked>> | 86% | 56,347 psi | 84% | 3363 fps | 99.8% |
| Ramshot Magnum | <<locked>> | 90% | 59,350 psi | 89% | 3346 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,696 psi | 58% | 2244 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 90% | 56,333 psi | 84% | 3406 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 94% | 60,147 psi | 90% | 3438 fps | 99.7% |
| Rottweil R 904 | <<locked>> | 84% | 57,899 psi | 87% | 3310 fps | 99.8% |
| Rottweil R 905 | <<locked>> | 84% | 57,058 psi | 86% | 3323 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 84% | 56,681 psi | 85% | 3320 fps | 100% |
| Somchem S361 | <<locked>> | 84% | 59,611 psi | 89% | 3294 fps | 99.7% |
| Somchem S365 | <<locked>> | 82% | 60,263 psi | 90% | 3307 fps | 100% |
| Somchem S385 | <<locked>> | 84% | 57,363 psi | 86% | 3287 fps | 100% |
| Vihtavuori N165 | <<locked>> | 88% | 57,638 psi | 86% | 3271 fps | 100% |
| Vihtavuori N170 | <<locked>> | 92% | 57,246 psi | 86% | 3294 fps | 96.7% |
| Vihtavuori N555 | <<locked>> | 84% | 56,753 psi | 85% | 3287 fps | 100% |
| Vihtavuori N560 | <<locked>> | 84% | 56,507 psi | 85% | 3369 fps | 99.5% |
| Vihtavuori N565 | <<locked>> | 90% | 57,914 psi | 87% | 3363 fps | 99.7% |
| Vihtavuori N568 | <<locked>> | 94% | 60,249 psi | 90% | 3442 fps | 99.5% |
| Vihtavuori N570 | <<locked>> | 94% | 57,421 psi | 86% | 3438 fps | 97.8% |
| Winchester StaBALL HD | <<locked>> | 88% | 60,350 psi | 90% | 3412 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 86% | 57,334 psi | 86% | 3281 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% | 46,296 psi | 69% | 3064 fps | 100% |
| Accurate MAGPRO | <<locked>> | 80% | 48,472 psi | 73% | 3212 fps | 97.8% |
| ADI AR 2209 | <<locked>> | 80% | 50,270 psi | 75% | 3212 fps | 99.6% |
| ADI AR 2213 | <<locked>> | 80% | 45,600 psi | 68% | 3150 fps | 98.1% |
| ADI AR 2217 | <<locked>> | 82% | 36,390 psi | 55% | 2917 fps | 95.7% |
| ADI AR 2218 | <<locked>> | 92% | 45,310 psi | 68% | 3209 fps | 95% |
| ADI AR 2225 | <<locked>> | 80% | 31,314 psi | 47% | 2808 fps | 96.6% |
| Alliant Reloder-19 | <<locked>> | 80% | 50,183 psi | 75% | 3205 fps | 99.6% |
| Alliant Reloder-22 | <<locked>> | 80% | 46,383 psi | 70% | 3153 fps | 99.1% |
| Alliant Reloder-23 | <<locked>> | 80% | 44,991 psi | 67% | 3081 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 39,247 psi | 59% | 3012 fps | 99.8% |
| Alliant Reloder-26 | <<locked>> | 80% | 51,895 psi | 78% | 3274 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 90% | 46,876 psi | 70% | 3199 fps | 95.6% |
| Alliant Reloder-50 | <<locked>> | 94% | 47,007 psi | 70% | 3186 fps | 95% |
| Baschieri & Pellagri 109 | <<locked>> | 82% | 46,615 psi | 70% | 3107 fps | 95.9% |
| Bofors RP15 | <<locked>> | 80% | 43,178 psi | 65% | 3081 fps | 98.4% |
| Bofors RP30 | <<locked>> | 80% | 36,724 psi | 55% | 2936 fps | 95.8% |
| Bofors RP5 | <<locked>> | 80% | 46,383 psi | 70% | 3153 fps | 99.1% |
| Hodgdon H1000 | <<locked>> | 80% | 37,014 psi | 55% | 2936 fps | 96.6% |
| Hodgdon H4831 | <<locked>> | 80% | 48,037 psi | 72% | 3146 fps | 98.1% |
| Hodgdon H4831 SC | <<locked>> | 80% | 47,239 psi | 71% | 3130 fps | 97.9% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 54,027 psi | 81% | 3186 fps | 100% |
| Hodgdon Retumbo | 84.4 gr | 80% | 38,305 psi | 57% | 3061 fps | 98.1% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,369 psi | 43% | 1975 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 55,753 psi | 84% | 3255 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 48,675 psi | 73% | 3133 fps | 98.4% |
| IMR 7828 SSC | <<locked>> | 80% | 44,295 psi | 66% | 3127 fps | 97.8% |
| IMR 8133 Enduron | <<locked>> | 86% | 35,723 psi | 54% | 2920 fps | 95.2% |
| Lovex S071 | <<locked>> | 80% | 39,784 psi | 60% | 2927 fps | 99.4% |
| Norma 217 | <<locked>> | 82% | 31,357 psi | 47% | 2812 fps | 95.5% |
| Norma MRP | <<locked>> | 80% | 49,516 psi | 74% | 3232 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 44,846 psi | 67% | 3143 fps | 98.3% |
| Ramshot Magnum | <<locked>> | 80% | 40,495 psi | 61% | 3002 fps | 98.7% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,066 psi | 44% | 2018 fps | 100% |
| ReloadSwiss RS 76 | 90.4 gr | 80% | 38,043 psi | 57% | 3035 fps | 99% |
| ReloadSwiss RS 80 | <<locked>> | 84% | 40,843 psi | 61% | 3054 fps | 95.8% |
| Rottweil R 904 | <<locked>> | 80% | 50,865 psi | 76% | 3182 fps | 99.1% |
| Rottweil R 905 | <<locked>> | 80% | 49,806 psi | 75% | 3192 fps | 99.6% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 49,458 psi | 74% | 3186 fps | 99.5% |
| Somchem S361 | <<locked>> | 80% | 52,025 psi | 78% | 3166 fps | 98.9% |
| Somchem S365 | <<locked>> | 80% | 56,289 psi | 84% | 3251 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 50,256 psi | 75% | 3163 fps | 99.9% |
| Vihtavuori N165 | <<locked>> | 80% | 44,048 psi | 66% | 3025 fps | 99.1% |
| Vihtavuori N170 | <<locked>> | 90% | 53,432 psi | 80% | 3225 fps | 95.8% |
| Vihtavuori N555 | <<locked>> | 80% | 49,734 psi | 75% | 3169 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 48,994 psi | 73% | 3228 fps | 98.4% |
| Vihtavuori N565 | <<locked>> | 80% | 40,886 psi | 61% | 3018 fps | 96.6% |
| Vihtavuori N568 | <<locked>> | 84% | 41,843 psi | 63% | 3077 fps | 95.5% |
| Vihtavuori N570 | 98.6 gr | 90% | 49,719 psi | 75% | 3291 fps | 96% |
| Winchester StaBALL HD | <<locked>> | 80% | 44,309 psi | 66% | 3150 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 46,499 psi | 70% | 3087 fps | 99.1% |
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 | 130gr | Sierra HPBT MatchKing. Hodgdon Retumbo delivers the highest muzzle velocity at 3,494 fps; across all powders the maximum-charge window runs from 2,198 fps to 3,494 fps. Alliant Reloder-50 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 130.0 gr projectile in 0.284" calls for a 1:11.5 twist; slower twists will usually not stabilise this weight. Alliant Reloder-50, Hodgdon TrailBoss, IMR 8133 Enduron 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 | 130gr | Sierra HPBT MatchKing 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.