Load Specifications
Load data in caliber 7.21 Firebird with .284 | 100gr | Barnes X S bullet and 65 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 IMR 7828 SSC.
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% | 56,826 psi | 85% | 3553 fps | 100% |
| Accurate 4350 | <<locked>> | 82% | 60,292 psi | 90% | 3658 fps | 100% |
| Accurate High Country | <<locked>> | 86% | 57,754 psi | 87% | 3714 fps | 98.7% |
| Accurate MAGPRO | <<locked>> | 88% | 58,929 psi | 88% | 3711 fps | 98% |
| ADI AR 2209 | <<locked>> | 86% | 56,608 psi | 85% | 3635 fps | 99.1% |
| ADI AR 2213 | <<locked>> | 90% | 59,190 psi | 89% | 3714 fps | 98.8% |
| ADI AR 2217 | <<locked>> | 98% | 58,146 psi | 87% | 3671 fps | 99.1% |
| ADI AR 2225ᴾ | <<locked>> | 100% | 57,000 psi | 85% | 3694 fps | 100% |
| Alliant Power Pro Varmint | <<locked>> | 86% | 56,971 psi | 85% | 3635 fps | 99.2% |
| Alliant Reloder-16 | <<locked>> | 84% | 60,234 psi | 90% | 3711 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 88% | 60,249 psi | 90% | 3694 fps | 99.6% |
| Alliant Reloder-22 | <<locked>> | 90% | 59,915 psi | 90% | 3714 fps | 99.6% |
| Alliant Reloder-23 | <<locked>> | 90% | 57,696 psi | 86% | 3619 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 94% | 58,030 psi | 87% | 3691 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 86% | 59,074 psi | 89% | 3720 fps | 100% |
| Baschieri & Pellagri 109 | <<locked>> | 92% | 59,698 psi | 89% | 3638 fps | 96.8% |
| Bofors RP15 | <<locked>> | 92% | 59,088 psi | 89% | 3698 fps | 99.5% |
| Bofors RP30 | <<locked>> | 96% | 58,378 psi | 88% | 3694 fps | 99.1% |
| Bofors RP5 | <<locked>> | 90% | 59,915 psi | 90% | 3714 fps | 99.6% |
| Hodgdon H1000 | <<locked>> | 96% | 59,712 psi | 90% | 3698 fps | 99.6% |
| Hodgdon H4831 | <<locked>> | 88% | 58,276 psi | 87% | 3635 fps | 98.2% |
| Hodgdon H4831 SC | <<locked>> | 88% | 57,232 psi | 86% | 3615 fps | 98% |
| Hodgdon Hybrid 100V | <<locked>> | 84% | 56,971 psi | 85% | 3560 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 94% | 56,898 psi | 85% | 3776 fps | 99.9% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,652 psi | 56% | 2461 fps | 100% |
| IMR 4350 | <<locked>> | 84% | 58,958 psi | 88% | 3619 fps | 99.8% |
| IMR 4831 | <<locked>> | 84% | 60,133 psi | 90% | 3635 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 88% | 58,595 psi | 88% | 3612 fps | 98.4% |
| IMR 7828 SSC | <<locked>> | 90% | 57,319 psi | 86% | 3688 fps | 98.6% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 52,663 psi | 79% | 3589 fps | 98.2% |
| Lovex S065 | <<locked>> | 82% | 59,364 psi | 89% | 3609 fps | 100% |
| Lovex S070 | <<locked>> | 82% | 58,015 psi | 87% | 3606 fps | 99.9% |
| Lovex S071 | <<locked>> | 94% | 58,363 psi | 87% | 3579 fps | 100% |
| Norma 204 | <<locked>> | 82% | 56,695 psi | 85% | 3615 fps | 99% |
| Norma 217ᴾ | <<locked>> | 100% | 53,722 psi | 81% | 3629 fps | 99.7% |
| Norma MRP | <<locked>> | 88% | 60,205 psi | 90% | 3737 fps | 100% |
| Norma URP | <<locked>> | 82% | 57,725 psi | 87% | 3625 fps | 100% |
| Ramshot Grand | <<locked>> | 90% | 58,914 psi | 88% | 3714 fps | 99.1% |
| Ramshot Hunter | <<locked>> | 82% | 56,782 psi | 85% | 3622 fps | 100% |
| Ramshot Magnum | <<locked>> | 92% | 57,928 psi | 87% | 3632 fps | 99.8% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,595 psi | 58% | 2513 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 82% | 60,263 psi | 90% | 3668 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 82% | 58,639 psi | 88% | 3698 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 94% | 58,581 psi | 88% | 3763 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 96% | 58,595 psi | 88% | 3704 fps | 98.2% |
| Rottweil R 904 | <<locked>> | 86% | 57,276 psi | 86% | 3602 fps | 98.5% |
| Rottweil R 905 | <<locked>> | 88% | 60,176 psi | 90% | 3688 fps | 99.6% |
| Shooters World Long Rifle | <<locked>> | 82% | 59,364 psi | 89% | 3609 fps | 100% |
| Shooters World SW4350 | <<locked>> | 82% | 58,015 psi | 87% | 3606 fps | 99.9% |
| SNPE Vectan Tubal 7000 | <<locked>> | 82% | 58,450 psi | 88% | 3543 fps | 99.9% |
| SNPE Vectan Tubal 8000 | <<locked>> | 88% | 59,741 psi | 90% | 3681 fps | 99.6% |
| Somchem S361 | <<locked>> | 86% | 59,509 psi | 89% | 3583 fps | 98.4% |
| Somchem S365 | <<locked>> | 84% | 59,379 psi | 89% | 3629 fps | 100% |
| Somchem S385 | <<locked>> | 86% | 57,000 psi | 85% | 3586 fps | 99.7% |
| Vihtavuori N160 | <<locked>> | 82% | 59,132 psi | 89% | 3609 fps | 100% |
| Vihtavuori N165 | <<locked>> | 90% | 56,797 psi | 85% | 3556 fps | 99.5% |
| Vihtavuori N550 | <<locked>> | 82% | 58,856 psi | 88% | 3615 fps | 100% |
| Vihtavuori N555 | <<locked>> | 88% | 59,944 psi | 90% | 3661 fps | 100% |
| Vihtavuori N560 | <<locked>> | 88% | 59,466 psi | 89% | 3730 fps | 98.5% |
| Vihtavuori N565 | <<locked>> | 92% | 57,217 psi | 86% | 3648 fps | 98.4% |
| Vihtavuori N568 | <<locked>> | 96% | 58,610 psi | 88% | 3707 fps | 97.7% |
| Vihtavuori N570 | <<locked>> | 98% | 59,828 psi | 90% | 3773 fps | 96.1% |
| Winchester 6.5 StaBALL | <<locked>> | 82% | 58,958 psi | 88% | 3540 fps | 100% |
| Winchester StaBALL HD | <<locked>> | 90% | 57,899 psi | 87% | 3717 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 88% | 56,739 psi | 85% | 3573 fps | 99.2% |
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% | 43,714 psi | 66% | 3297 fps | 98.8% |
| Accurate 4350 | <<locked>> | 80% | 56,434 psi | 85% | 3596 fps | 100% |
| Accurate High Country | <<locked>> | 80% | 46,934 psi | 70% | 3488 fps | 96.3% |
| Accurate MAGPRO | <<locked>> | 82% | 47,877 psi | 72% | 3484 fps | 95.2% |
| ADI AR 2209 | <<locked>> | 80% | 46,412 psi | 70% | 3428 fps | 97.2% |
| ADI AR 2213 | <<locked>> | 82% | 44,947 psi | 67% | 3419 fps | 95.6% |
| ADI AR 2217 | <<locked>> | 90% | 44,338 psi | 66% | 3383 fps | 95.9% |
| ADI AR 2225 | <<locked>> | 86% | 35,839 psi | 54% | 3199 fps | 95.9% |
| Alliant Power Pro Varmint | <<locked>> | 80% | 46,934 psi | 70% | 3432 fps | 97.4% |
| Alliant Reloder-16 | <<locked>> | 80% | 52,808 psi | 79% | 3586 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 80% | 46,514 psi | 70% | 3422 fps | 97.3% |
| Alliant Reloder-22 | <<locked>> | 80% | 42,873 psi | 64% | 3360 fps | 96.3% |
| Alliant Reloder-23 | <<locked>> | 80% | 41,582 psi | 62% | 3317 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 36,201 psi | 54% | 3215 fps | 97.6% |
| Alliant Reloder-26 | <<locked>> | 80% | 47,195 psi | 71% | 3497 fps | 99.9% |
| Baschieri & Pellagri 109 | <<locked>> | 88% | 52,605 psi | 79% | 3504 fps | 95% |
| Bofors RP15 | <<locked>> | 80% | 40,059 psi | 60% | 3284 fps | 95.1% |
| Bofors RP30 | <<locked>> | 86% | 41,655 psi | 62% | 3333 fps | 95.1% |
| Bofors RP5 | <<locked>> | 80% | 42,873 psi | 64% | 3360 fps | 96.3% |
| Hodgdon H1000 | <<locked>> | 86% | 42,192 psi | 63% | 3333 fps | 95.8% |
| Hodgdon H4831 | <<locked>> | 82% | 47,718 psi | 72% | 3422 fps | 95.8% |
| Hodgdon H4831 SC | <<locked>> | 82% | 46,847 psi | 70% | 3402 fps | 95.5% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 50,227 psi | 75% | 3442 fps | 100% |
| Hodgdon Retumbo | 88.5 gr | 82% | 37,797 psi | 57% | 3310 fps | 95% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,224 psi | 42% | 2218 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 51,967 psi | 78% | 3491 fps | 99.1% |
| IMR 4831 | <<locked>> | 80% | 52,910 psi | 79% | 3514 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 45,542 psi | 68% | 3343 fps | 95.3% |
| IMR 7828 SSC | 88.4 gr | 82% | 43,555 psi | 65% | 3392 fps | 95.1% |
| IMR 8133 Enduron | <<locked>> | 94% | 43,062 psi | 65% | 3379 fps | 95.5% |
| Lovex S065 | <<locked>> | 80% | 55,811 psi | 84% | 3547 fps | 100% |
| Lovex S070 | <<locked>> | 80% | 54,549 psi | 82% | 3543 fps | 99.7% |
| Lovex S071 | <<locked>> | 80% | 37,855 psi | 57% | 3153 fps | 97.3% |
| Norma 204 | <<locked>> | 80% | 53,040 psi | 80% | 3547 fps | 98.5% |
| Norma 217 | <<locked>> | 90% | 38,189 psi | 57% | 3274 fps | 96.1% |
| Norma MRP | <<locked>> | 80% | 45,484 psi | 68% | 3448 fps | 98.3% |
| Norma URP | <<locked>> | 80% | 54,201 psi | 81% | 3563 fps | 100% |
| Ramshot Grand | <<locked>> | 82% | 43,830 psi | 66% | 3406 fps | 95.7% |
| Ramshot Hunter | <<locked>> | 80% | 53,185 psi | 80% | 3556 fps | 99.8% |
| Ramshot Magnum | <<locked>> | 80% | 37,304 psi | 56% | 3189 fps | 95.4% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,008 psi | 43% | 2270 fps | 100% |
| ReloadSwiss RS 62 | <<locked>> | 80% | 56,420 psi | 85% | 3606 fps | 100% |
| ReloadSwiss RS 70 | <<locked>> | 80% | 54,534 psi | 82% | 3625 fps | 100% |
| ReloadSwiss RS 76 | 92.4 gr | 80% | 35,056 psi | 53% | 3202 fps | 95.2% |
| ReloadSwiss RS 80 | <<locked>> | 90% | 46,746 psi | 70% | 3468 fps | 95.3% |
| Rottweil R 904 | <<locked>> | 80% | 47,398 psi | 71% | 3399 fps | 96.4% |
| Rottweil R 905 | <<locked>> | 80% | 46,195 psi | 69% | 3412 fps | 97.3% |
| Shooters World Long Rifle | <<locked>> | 80% | 55,811 psi | 84% | 3547 fps | 100% |
| Shooters World SW4350 | <<locked>> | 80% | 54,549 psi | 82% | 3543 fps | 99.7% |
| SNPE Vectan Tubal 7000 | <<locked>> | 80% | 54,911 psi | 82% | 3484 fps | 99.7% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 45,832 psi | 69% | 3402 fps | 97.2% |
| Somchem S361 | <<locked>> | 80% | 48,791 psi | 73% | 3379 fps | 96.2% |
| Somchem S365 | <<locked>> | 80% | 51,938 psi | 78% | 3510 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 47,007 psi | 70% | 3389 fps | 98.3% |
| Vihtavuori N160 | <<locked>> | 80% | 55,463 psi | 83% | 3550 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 41,089 psi | 62% | 3235 fps | 96.5% |
| Vihtavuori N550 | <<locked>> | 80% | 55,172 psi | 83% | 3553 fps | 100% |
| Vihtavuori N555 | <<locked>> | 80% | 46,427 psi | 70% | 3415 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 45,078 psi | 68% | 3428 fps | 95% |
| Vihtavuori N565 | <<locked>> | 86% | 46,717 psi | 70% | 3432 fps | 96% |
| Vihtavuori N568 | <<locked>> | 92% | 50,894 psi | 76% | 3556 fps | 95.8% |
| Vihtavuori N570 | <<locked>> | 96% | 55,579 psi | 83% | 3691 fps | 95% |
| Winchester 6.5 StaBALL | <<locked>> | 80% | 55,027 psi | 82% | 3478 fps | 100% |
| Winchester StaBALL HD | <<locked>> | 80% | 39,581 psi | 59% | 3369 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 43,221 psi | 65% | 3294 fps | 96.5% |
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 65 powders for 7.21 Firebird loaded with the .284 | 100gr | Barnes X S. Hodgdon Retumbo delivers the highest muzzle velocity at 3,776 fps; across all powders the maximum-charge window runs from 2,461 fps to 3,776 fps. ADI AR 2225 gives the best case fill at 100 %, and 65 of the 65 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 100.0 gr projectile in 0.284" calls for a 1:14.5 twist; slower twists will usually not stabilise this weight. ADI AR 2225, 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. Hodgdon Retumbo, ReloadSwiss RS 76, IMR 7828 SSC rank at the top here: for 7.21 Firebird with the .284 | 100gr | Barnes X S 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.