Load Specifications
Load data in caliber 7.21 Firebird with .284 | 128gr | IBEX TRD bullet and 50 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Hodgdon Retumbo, ReloadSwiss RS 76 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% | 58,465 psi | 88% | 3287 fps | 100% |
| Accurate MAGPRO | <<locked>> | 84% | 57,145 psi | 86% | 3392 fps | 99.1% |
| ADI AR 2209 | <<locked>> | 84% | 58,465 psi | 88% | 3373 fps | 100% |
| ADI AR 2213 | <<locked>> | 86% | 57,435 psi | 86% | 3389 fps | 99.7% |
| ADI AR 2217 | <<locked>> | 94% | 56,666 psi | 85% | 3360 fps | 99.9% |
| ADI AR 2218 | <<locked>> | 98% | 57,827 psi | 87% | 3491 fps | 98.4% |
| ADI AR 2225 | <<locked>> | 96% | 56,362 psi | 84% | 3389 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 84% | 58,175 psi | 87% | 3360 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 86% | 58,189 psi | 87% | 3386 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 88% | 60,162 psi | 90% | 3343 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 90% | 56,927 psi | 85% | 3366 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 82% | 57,305 psi | 86% | 3379 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 96% | 60,104 psi | 90% | 3471 fps | 98.5% |
| Alliant Reloder-50 | <<locked>> | 98% | 56,681 psi | 85% | 3392 fps | 97.5% |
| Baschieri & Pellagri 109 | <<locked>> | 88% | 57,508 psi | 86% | 3330 fps | 98.2% |
| Bofors RP15 | <<locked>> | 88% | 57,595 psi | 86% | 3376 fps | 100% |
| Bofors RP30 | <<locked>> | 92% | 57,130 psi | 86% | 3386 fps | 99.9% |
| Bofors RP5 | <<locked>> | 86% | 58,189 psi | 87% | 3386 fps | 100% |
| Hodgdon H1000 | <<locked>> | 92% | 58,262 psi | 87% | 3386 fps | 100% |
| Hodgdon H4831 | <<locked>> | 86% | 59,959 psi | 90% | 3376 fps | 99.6% |
| Hodgdon H4831 SC | <<locked>> | 86% | 59,045 psi | 89% | 3360 fps | 99.5% |
| Hodgdon Hybrid 100V | <<locked>> | 82% | 58,900 psi | 88% | 3274 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 90% | 56,362 psi | 84% | 3461 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,913 psi | 57% | 2208 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 86% | 59,872 psi | 90% | 3350 fps | 99.7% |
| IMR 7828 SSC | <<locked>> | 88% | 59,973 psi | 90% | 3438 fps | 99.9% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 59,582 psi | 89% | 3435 fps | 100% |
| Lovex S071 | <<locked>> | 92% | 60,350 psi | 90% | 3314 fps | 100% |
| Norma 217 | <<locked>> | 98% | 57,159 psi | 86% | 3399 fps | 100% |
| Norma MRP | <<locked>> | 84% | 58,436 psi | 88% | 3402 fps | 100% |
| Ramshot Grand | <<locked>> | 86% | 57,450 psi | 86% | 3396 fps | 99.9% |
| Ramshot Magnum | <<locked>> | 88% | 56,188 psi | 84% | 3314 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,986 psi | 58% | 2257 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 90% | 57,638 psi | 86% | 3445 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 92% | 57,116 psi | 86% | 3406 fps | 99.4% |
| Rottweil R 904 | <<locked>> | 84% | 58,842 psi | 88% | 3337 fps | 99.8% |
| Rottweil R 905 | <<locked>> | 84% | 58,276 psi | 87% | 3356 fps | 100% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 52,054 psi | 78% | 3235 fps | 96% |
| SNPE Vectan Tubal 8000 | <<locked>> | 84% | 57,885 psi | 87% | 3353 fps | 100% |
| Somchem S361 | <<locked>> | 82% | 56,782 psi | 85% | 3261 fps | 99.3% |
| Somchem S385 | <<locked>> | 84% | 58,740 psi | 88% | 3320 fps | 100% |
| Vihtavuori N165 | <<locked>> | 88% | 58,697 psi | 88% | 3301 fps | 100% |
| Vihtavuori N170 | <<locked>> | 92% | 58,494 psi | 88% | 3327 fps | 96.8% |
| Vihtavuori N555 | <<locked>> | 84% | 58,363 psi | 87% | 3323 fps | 100% |
| Vihtavuori N560 | <<locked>> | 84% | 57,595 psi | 86% | 3402 fps | 99.5% |
| Vihtavuori N565 | <<locked>> | 90% | 59,437 psi | 89% | 3402 fps | 99.8% |
| Vihtavuori N568 | <<locked>> | 92% | 57,305 psi | 86% | 3409 fps | 99% |
| Vihtavuori N570 | <<locked>> | 94% | 58,813 psi | 88% | 3478 fps | 97.9% |
| Winchester StaBALL HD | <<locked>> | 86% | 57,290 psi | 86% | 3386 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 86% | 58,392 psi | 88% | 3310 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% | 48,138 psi | 72% | 3110 fps | 100% |
| Accurate MAGPRO | <<locked>> | 80% | 49,734 psi | 75% | 3251 fps | 97.9% |
| ADI AR 2209 | <<locked>> | 80% | 51,271 psi | 77% | 3245 fps | 99.6% |
| ADI AR 2213 | <<locked>> | 80% | 46,746 psi | 70% | 3186 fps | 98.2% |
| ADI AR 2217 | <<locked>> | 82% | 37,710 psi | 57% | 2963 fps | 96% |
| ADI AR 2218 | 101.9 gr | 92% | 46,514 psi | 70% | 3248 fps | 95.2% |
| ADI AR 2225 | <<locked>> | 80% | 32,822 psi | 49% | 2867 fps | 97.2% |
| Alliant Reloder-19 | <<locked>> | 80% | 51,242 psi | 77% | 3238 fps | 99.6% |
| Alliant Reloder-22 | <<locked>> | 80% | 47,718 psi | 72% | 3192 fps | 99.2% |
| Alliant Reloder-23 | <<locked>> | 80% | 46,340 psi | 69% | 3120 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 40,596 psi | 61% | 3061 fps | 99.9% |
| Alliant Reloder-26 | <<locked>> | 80% | 53,330 psi | 80% | 3314 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 90% | 48,298 psi | 72% | 3245 fps | 95.9% |
| Alliant Reloder-50 | <<locked>> | 94% | 48,921 psi | 73% | 3241 fps | 95.5% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 44,541 psi | 67% | 3071 fps | 95% |
| Bofors RP15 | <<locked>> | 80% | 44,527 psi | 67% | 3123 fps | 98.6% |
| Bofors RP30 | <<locked>> | 80% | 38,334 psi | 57% | 2992 fps | 96.3% |
| Bofors RP5 | <<locked>> | 80% | 47,718 psi | 72% | 3192 fps | 99.2% |
| Hodgdon H1000 | <<locked>> | 80% | 38,305 psi | 57% | 2982 fps | 96.9% |
| Hodgdon H4831 | <<locked>> | 80% | 49,139 psi | 74% | 3179 fps | 98.2% |
| Hodgdon H4831 SC | <<locked>> | 80% | 48,370 psi | 73% | 3163 fps | 98% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 55,158 psi | 83% | 3219 fps | 100% |
| Hodgdon Retumbo | 83.6 gr | 80% | 39,668 psi | 59% | 3110 fps | 98.4% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,529 psi | 43% | 1985 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 49,676 psi | 74% | 3166 fps | 98.4% |
| IMR 7828 SSC | <<locked>> | 80% | 45,498 psi | 68% | 3166 fps | 98% |
| IMR 8133 Enduron | <<locked>> | 86% | 37,420 psi | 56% | 2979 fps | 95.8% |
| Lovex S071 | <<locked>> | 80% | 41,597 psi | 62% | 2979 fps | 99.6% |
| Norma 217 | <<locked>> | 80% | 30,879 psi | 46% | 2812 fps | 95.2% |
| Norma MRP | <<locked>> | 80% | 50,908 psi | 76% | 3274 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 46,180 psi | 69% | 3186 fps | 98.5% |
| Ramshot Magnum | <<locked>> | 80% | 42,018 psi | 63% | 3048 fps | 98.9% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,414 psi | 44% | 2034 fps | 100% |
| ReloadSwiss RS 76 | 89.5 gr | 80% | 39,508 psi | 59% | 3087 fps | 99.3% |
| ReloadSwiss RS 80 | <<locked>> | 82% | 39,552 psi | 59% | 3038 fps | 95.1% |
| Rottweil R 904 | <<locked>> | 80% | 51,851 psi | 78% | 3212 fps | 99.1% |
| Rottweil R 905 | <<locked>> | 80% | 51,039 psi | 77% | 3228 fps | 99.6% |
| SNPE Vectan SP 13 | <<locked>> | 98% | 48,689 psi | 73% | 3169 fps | 95% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 50,676 psi | 76% | 3222 fps | 99.6% |
| Somchem S361 | <<locked>> | 80% | 53,214 psi | 80% | 3199 fps | 98.9% |
| Somchem S385 | <<locked>> | 80% | 51,663 psi | 77% | 3202 fps | 99.9% |
| Vihtavuori N165 | <<locked>> | 80% | 45,339 psi | 68% | 3064 fps | 99.2% |
| Vihtavuori N170 | <<locked>> | 88% | 51,271 psi | 77% | 3192 fps | 95% |
| Vihtavuori N555 | <<locked>> | 80% | 51,401 psi | 77% | 3209 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 50,299 psi | 75% | 3268 fps | 98.5% |
| Vihtavuori N565 | <<locked>> | 80% | 42,569 psi | 64% | 3071 fps | 96.9% |
| Vihtavuori N568 | <<locked>> | 84% | 43,308 psi | 65% | 3127 fps | 95.9% |
| Vihtavuori N570 | <<locked>> | 88% | 47,587 psi | 71% | 3258 fps | 95.1% |
| Winchester StaBALL HD | <<locked>> | 80% | 45,977 psi | 69% | 3202 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 47,761 psi | 72% | 3123 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 50 powders for 7.21 Firebird loaded with the .284 | 128gr | IBEX TRD. ADI AR 2218 delivers the highest muzzle velocity at 3,491 fps; across all powders the maximum-charge window runs from 2,208 fps to 3,491 fps. Hodgdon TrailBoss gives the best case fill at 100 %, and 50 of the 50 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 128.0 gr projectile in 0.284" calls for a 1:11.0 twist; slower twists will usually not stabilise this weight. Hodgdon TrailBoss, IMR 8133 Enduron, 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. Hodgdon Retumbo, ReloadSwiss RS 76, ADI AR 2218 rank at the top here: for 7.21 Firebird with the .284 | 128gr | IBEX TRD 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.