Load Specifications
Load data in caliber 7.21 Firebird with .284 | 110gr | Speer TNT bullet and 64 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Hodgdon Retumbo, Vihtavuori N570 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>> | 90% | 60,133 psi | 90% | 3501 fps | 100% |
| Accurate 4350 | <<locked>> | 82% | 59,959 psi | 90% | 3540 fps | 100% |
| Accurate MAGPRO | <<locked>> | 88% | 59,292 psi | 89% | 3612 fps | 98.7% |
| ADI AR 2209 | <<locked>> | 86% | 57,188 psi | 86% | 3540 fps | 99.6% |
| ADI AR 2213 | <<locked>> | 90% | 59,799 psi | 90% | 3615 fps | 99.4% |
| ADI AR 2217 | <<locked>> | 98% | 58,885 psi | 88% | 3579 fps | 99.6% |
| ADI AR 2218ᴾ | <<locked>> | 100% | 55,898 psi | 84% | 3609 fps | 96.7% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 57,754 psi | 87% | 3596 fps | 100% |
| Alliant Reloder-16 | <<locked>> | 82% | 57,014 psi | 85% | 3540 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 86% | 56,768 psi | 85% | 3524 fps | 99.6% |
| Alliant Reloder-22 | <<locked>> | 90% | 60,118 psi | 90% | 3609 fps | 99.9% |
| Alliant Reloder-23 | <<locked>> | 90% | 58,015 psi | 87% | 3510 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 94% | 58,537 psi | 88% | 3579 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 86% | 59,219 psi | 89% | 3606 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 98% | 57,827 psi | 87% | 3596 fps | 97% |
| Baschieri & Pellagri 109 | <<locked>> | 90% | 56,608 psi | 85% | 3484 fps | 96.9% |
| Bofors RP15 | <<locked>> | 92% | 59,480 psi | 89% | 3593 fps | 99.8% |
| Bofors RP30 | <<locked>> | 96% | 58,479 psi | 88% | 3586 fps | 99.6% |
| Bofors RP5 | <<locked>> | 90% | 60,118 psi | 90% | 3609 fps | 99.9% |
| Hodgdon H1000 | <<locked>> | 94% | 56,246 psi | 84% | 3533 fps | 99.6% |
| Hodgdon H4831 | <<locked>> | 88% | 58,827 psi | 88% | 3540 fps | 98.9% |
| Hodgdon H4831 SC | <<locked>> | 88% | 57,682 psi | 86% | 3520 fps | 98.7% |
| Hodgdon Hybrid 100V | <<locked>> | 84% | 57,232 psi | 86% | 3448 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 94% | 57,580 psi | 86% | 3671 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,463 psi | 56% | 2362 fps | 100% |
| IMR 4350 | <<locked>> | 84% | 59,219 psi | 89% | 3514 fps | 100% |
| IMR 4831 | <<locked>> | 84% | 60,046 psi | 90% | 3520 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 88% | 58,885 psi | 88% | 3517 fps | 99% |
| IMR 7828 SSC | <<locked>> | 90% | 58,001 psi | 87% | 3589 fps | 99.2% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 52,808 psi | 79% | 3491 fps | 98.8% |
| Lovex S065 | <<locked>> | 82% | 59,161 psi | 89% | 3494 fps | 100% |
| Lovex S070 | <<locked>> | 82% | 57,754 psi | 87% | 3491 fps | 100% |
| Lovex S071 | <<locked>> | 94% | 57,870 psi | 87% | 3465 fps | 100% |
| Norma 204 | <<locked>> | 82% | 56,913 psi | 85% | 3514 fps | 99.5% |
| Norma 217ᴾ | <<locked>> | 100% | 53,882 psi | 81% | 3520 fps | 99.9% |
| Norma MRP | <<locked>> | 86% | 56,362 psi | 84% | 3556 fps | 100% |
| Norma URP | <<locked>> | 82% | 57,754 psi | 87% | 3510 fps | 100% |
| Ramshot Grand | <<locked>> | 90% | 59,741 psi | 90% | 3622 fps | 99.6% |
| Ramshot Hunter | <<locked>> | 82% | 56,898 psi | 85% | 3510 fps | 100% |
| Ramshot Magnum | <<locked>> | 92% | 58,392 psi | 88% | 3530 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,363 psi | 57% | 2415 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 82% | 59,146 psi | 89% | 3586 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 94% | 59,509 psi | 89% | 3661 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 96% | 58,987 psi | 88% | 3609 fps | 98.9% |
| Rottweil R 904 | <<locked>> | 86% | 57,682 psi | 86% | 3504 fps | 99.1% |
| Rottweil R 905 | <<locked>> | 86% | 56,507 psi | 85% | 3517 fps | 99.6% |
| Shooters World Long Rifle | <<locked>> | 82% | 59,161 psi | 89% | 3494 fps | 100% |
| Shooters World SW4350 | <<locked>> | 82% | 57,754 psi | 87% | 3491 fps | 100% |
| SNPE Vectan Tubal 7000 | <<locked>> | 82% | 58,407 psi | 88% | 3438 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 88% | 60,002 psi | 90% | 3579 fps | 99.9% |
| Somchem S361 | <<locked>> | 86% | 59,582 psi | 89% | 3488 fps | 99% |
| Somchem S365 | <<locked>> | 84% | 59,466 psi | 89% | 3514 fps | 100% |
| Somchem S385 | <<locked>> | 86% | 56,956 psi | 85% | 3481 fps | 99.9% |
| Vihtavuori N160 | <<locked>> | 82% | 59,422 psi | 89% | 3504 fps | 100% |
| Vihtavuori N165 | <<locked>> | 90% | 57,029 psi | 85% | 3458 fps | 99.8% |
| Vihtavuori N550 | <<locked>> | 82% | 58,755 psi | 88% | 3504 fps | 100% |
| Vihtavuori N555 | <<locked>> | 88% | 59,799 psi | 90% | 3543 fps | 100% |
| Vihtavuori N560 | <<locked>> | 88% | 59,770 psi | 90% | 3625 fps | 99.1% |
| Vihtavuori N565 | <<locked>> | 92% | 56,927 psi | 85% | 3537 fps | 98.9% |
| Vihtavuori N568 | <<locked>> | 96% | 59,045 psi | 89% | 3612 fps | 98.5% |
| Vihtavuori N570 | <<locked>> | 96% | 56,043 psi | 84% | 3599 fps | 96.1% |
| Winchester 6.5 StaBALL | <<locked>> | 82% | 59,379 psi | 89% | 3432 fps | 100% |
| Winchester StaBALL HD | <<locked>> | 90% | 58,392 psi | 88% | 3599 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 88% | 57,000 psi | 85% | 3474 fps | 99.7% |
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% | 42,438 psi | 64% | 3173 fps | 99.1% |
| Accurate 4350 | <<locked>> | 80% | 55,840 psi | 84% | 3471 fps | 100% |
| Accurate MAGPRO | <<locked>> | 82% | 47,572 psi | 71% | 3379 fps | 96.1% |
| ADI AR 2209 | <<locked>> | 80% | 46,354 psi | 69% | 3323 fps | 97.9% |
| ADI AR 2213 | <<locked>> | 80% | 41,669 psi | 62% | 3238 fps | 95.4% |
| ADI AR 2217 | <<locked>> | 88% | 41,118 psi | 62% | 3209 fps | 95.8% |
| ADI AR 2218 | <<locked>> | 98% | 51,735 psi | 78% | 3520 fps | 95.4% |
| ADI AR 2225 | <<locked>> | 84% | 32,721 psi | 49% | 3012 fps | 95.3% |
| Alliant Reloder-16 | <<locked>> | 80% | 53,258 psi | 80% | 3478 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 80% | 46,340 psi | 69% | 3317 fps | 98% |
| Alliant Reloder-22 | <<locked>> | 80% | 42,409 psi | 64% | 3248 fps | 97% |
| Alliant Reloder-23 | <<locked>> | 80% | 41,046 psi | 62% | 3196 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 35,505 psi | 53% | 3097 fps | 98.1% |
| Alliant Reloder-26 | <<locked>> | 80% | 46,992 psi | 70% | 3383 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 96% | 53,316 psi | 80% | 3510 fps | 95.9% |
| Baschieri & Pellagri 109 | <<locked>> | 86% | 49,559 psi | 74% | 3346 fps | 95.1% |
| Bofors RP15 | <<locked>> | 80% | 39,479 psi | 59% | 3173 fps | 95.9% |
| Bofors RP30 | <<locked>> | 86% | 41,176 psi | 62% | 3225 fps | 95.8% |
| Bofors RP5 | <<locked>> | 80% | 42,409 psi | 64% | 3248 fps | 97% |
| Hodgdon H1000 | <<locked>> | 84% | 39,001 psi | 58% | 3156 fps | 95.6% |
| Hodgdon H4831 | <<locked>> | 80% | 44,338 psi | 66% | 3248 fps | 95.7% |
| Hodgdon H4831 SC | <<locked>> | 80% | 43,497 psi | 65% | 3228 fps | 95.4% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 50,009 psi | 75% | 3327 fps | 100% |
| Hodgdon Retumbo | 88.8 gr | 82% | 37,231 psi | 56% | 3199 fps | 95.9% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,007 psi | 42% | 2126 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 51,982 psi | 78% | 3386 fps | 99.6% |
| IMR 4831 | <<locked>> | 80% | 52,533 psi | 79% | 3396 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 45,324 psi | 68% | 3245 fps | 96.2% |
| IMR 7828 SSC | <<locked>> | 82% | 43,395 psi | 65% | 3291 fps | 96.1% |
| IMR 8133 Enduron | <<locked>> | 92% | 39,755 psi | 60% | 3199 fps | 95.1% |
| Lovex S065 | <<locked>> | 80% | 55,535 psi | 83% | 3432 fps | 100% |
| Lovex S070 | <<locked>> | 80% | 54,215 psi | 81% | 3428 fps | 99.9% |
| Lovex S071 | <<locked>> | 80% | 36,361 psi | 55% | 3022 fps | 97.5% |
| Norma 204 | <<locked>> | 80% | 53,098 psi | 80% | 3442 fps | 99.1% |
| Norma 217 | <<locked>> | 88% | 34,751 psi | 52% | 3077 fps | 95.4% |
| Norma MRP | <<locked>> | 80% | 45,310 psi | 68% | 3337 fps | 98.9% |
| Norma URP | <<locked>> | 80% | 54,085 psi | 81% | 3448 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 40,466 psi | 61% | 3222 fps | 95.4% |
| Ramshot Hunter | <<locked>> | 80% | 53,185 psi | 80% | 3445 fps | 100% |
| Ramshot Magnum | <<locked>> | 80% | 36,593 psi | 55% | 3074 fps | 96% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 28,761 psi | 43% | 2178 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 54,868 psi | 82% | 3517 fps | 100% |
| ReloadSwiss RS 76 | 92.8 gr | 80% | 34,272 psi | 51% | 3087 fps | 95.9% |
| ReloadSwiss RS 80 | <<locked>> | 90% | 46,557 psi | 70% | 3363 fps | 96.1% |
| Rottweil R 904 | <<locked>> | 80% | 47,253 psi | 71% | 3297 fps | 97.2% |
| Rottweil R 905 | <<locked>> | 80% | 45,832 psi | 69% | 3304 fps | 98% |
| Shooters World Long Rifle | <<locked>> | 80% | 55,535 psi | 83% | 3432 fps | 100% |
| Shooters World SW4350 | <<locked>> | 80% | 54,215 psi | 81% | 3428 fps | 99.9% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 54,592 psi | 82% | 3376 fps | 99.9% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 45,484 psi | 68% | 3297 fps | 97.9% |
| Somchem S361 | <<locked>> | 80% | 48,472 psi | 73% | 3278 fps | 97% |
| Somchem S365 | <<locked>> | 80% | 51,735 psi | 78% | 3392 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 46,383 psi | 70% | 3274 fps | 98.8% |
| Vihtavuori N160 | <<locked>> | 80% | 55,463 psi | 83% | 3438 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 40,495 psi | 61% | 3123 fps | 97.1% |
| Vihtavuori N550 | <<locked>> | 80% | 54,984 psi | 82% | 3438 fps | 100% |
| Vihtavuori N555 | <<locked>> | 80% | 45,614 psi | 68% | 3291 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 44,976 psi | 67% | 3323 fps | 95.9% |
| Vihtavuori N565 | <<locked>> | 84% | 43,004 psi | 64% | 3245 fps | 95.6% |
| Vihtavuori N568 | <<locked>> | 90% | 47,239 psi | 71% | 3376 fps | 95.6% |
| Vihtavuori N570 | 105.7 gr | 94% | 52,098 psi | 78% | 3517 fps | 95% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 55,361 psi | 83% | 3373 fps | 100% |
| Winchester StaBALL HD | <<locked>> | 80% | 39,247 psi | 59% | 3241 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 42,859 psi | 64% | 3189 fps | 97.2% |
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 71 powders for 7.21 Firebird loaded with the .284 | 110gr | Speer TNT. Hodgdon Retumbo delivers the highest muzzle velocity at 3,671 fps; across all powders the maximum-charge window runs from 2,362 fps to 3,671 fps. Accurate 8700 gives the best case fill at 100 %, and 71 of the 71 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (460 MPa), the top charges use 56–90 %, leaving at least 10 % headroom. The 110.0 gr projectile in 0.284" calls for a 1:14.0 twist; slower twists will usually not stabilise this weight. Accurate 8700, ADI AR 2218, ADI AR 2225 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, Vihtavuori N570, ReloadSwiss RS 76 rank at the top here: for 7.21 Firebird with the .284 | 110gr | Speer TNT they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Accurate 8700, IMR 7977 Enduron, 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.