Load Specifications
Load data in caliber 7.21 Firebird with .284 | 160gr | Speer Deep Curl Soft Point bullet and 47 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are ADI AR 2218, Vihtavuori N570 and Alliant Reloder-50.
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>> | 82% | 56,623 psi | 85% | 2982 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 58,015 psi | 87% | 3114 fps | 99.3% |
| Accurate MAGPRO | <<locked>> | 82% | 60,089 psi | 90% | 3166 fps | 100% |
| ADI AR 2213 | <<locked>> | 84% | 60,365 psi | 90% | 3156 fps | 100% |
| ADI AR 2217 | <<locked>> | 90% | 56,565 psi | 85% | 3084 fps | 100% |
| ADI AR 2218 | <<locked>> | 94% | 57,769 psi | 87% | 3232 fps | 99.8% |
| ADI AR 2225 | <<locked>> | 92% | 57,014 psi | 85% | 3110 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 82% | 56,971 psi | 85% | 3087 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 84% | 59,263 psi | 89% | 3038 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 86% | 56,768 psi | 85% | 3071 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 92% | 60,060 psi | 90% | 3202 fps | 99.7% |
| Alliant Reloder-50 | <<locked>> | 94% | 56,347 psi | 84% | 3133 fps | 99.1% |
| Baschieri & Pellagri 109 | <<locked>> | 86% | 60,176 psi | 90% | 3117 fps | 99.7% |
| Bofors RP15 | <<locked>> | 84% | 56,565 psi | 85% | 3081 fps | 100% |
| Bofors RP30 | <<locked>> | 88% | 56,797 psi | 85% | 3100 fps | 100% |
| Bofors RP5 | <<locked>> | 82% | 56,971 psi | 85% | 3087 fps | 100% |
| Hodgdon H1000 | <<locked>> | 88% | 57,957 psi | 87% | 3104 fps | 100% |
| Hodgdon H4831 | <<locked>> | 82% | 58,523 psi | 88% | 3081 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 82% | 57,421 psi | 86% | 3064 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 86% | 56,971 psi | 85% | 3176 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,159 psi | 57% | 2005 fps | 100% |
| Hodgdon US 869 | <<locked>> | 98% | 58,537 psi | 88% | 3110 fps | 96.2% |
| IMR 4955 Enduron | <<locked>> | 82% | 58,117 psi | 87% | 3051 fps | 100% |
| IMR 7828 SSC | <<locked>> | 84% | 59,248 psi | 89% | 3146 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 88% | 57,130 psi | 86% | 3015 fps | 97.2% |
| IMR 8133 Enduron | <<locked>> | 96% | 59,654 psi | 89% | 3159 fps | 100% |
| Lovex D100 | <<locked>> | 92% | 59,088 psi | 89% | 3071 fps | 96.7% |
| Lovex S071 | <<locked>> | 88% | 59,045 psi | 89% | 3015 fps | 100% |
| Norma 217 | <<locked>> | 94% | 57,580 psi | 86% | 3120 fps | 100% |
| Ramshot Grand | <<locked>> | 82% | 56,884 psi | 85% | 3107 fps | 100% |
| Ramshot LRT | <<locked>> | 94% | 57,101 psi | 86% | 3150 fps | 96% |
| Ramshot Magnum | <<locked>> | 86% | 59,466 psi | 89% | 3087 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,276 psi | 59% | 2051 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 86% | 57,740 psi | 87% | 3150 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 88% | 56,652 psi | 85% | 3130 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 92% | 59,088 psi | 89% | 3071 fps | 96.7% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 59,292 psi | 89% | 3114 fps | 99.2% |
| SNPE Vectan Tubal 8000 | <<locked>> | 82% | 60,365 psi | 90% | 3107 fps | 100% |
| Vihtavuori 20N29ᴾ | <<locked>> | 100% | 52,750 psi | 79% | 3022 fps | 96.8% |
| Vihtavuori 24N41 | <<locked>> | 96% | 58,914 psi | 88% | 3120 fps | 96.2% |
| Vihtavuori N165 | <<locked>> | 84% | 57,319 psi | 86% | 3009 fps | 100% |
| Vihtavuori N170 | <<locked>> | 88% | 57,116 psi | 86% | 3054 fps | 98.5% |
| Vihtavuori N565 | <<locked>> | 86% | 58,378 psi | 88% | 3114 fps | 100% |
| Vihtavuori N568 | <<locked>> | 88% | 57,000 psi | 85% | 3133 fps | 99.9% |
| Vihtavuori N570 | <<locked>> | 90% | 58,697 psi | 88% | 3205 fps | 99.4% |
| Winchester StaBALL HD | <<locked>> | 82% | 57,450 psi | 86% | 3084 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 82% | 56,855 psi | 85% | 3018 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% | 52,968 psi | 79% | 2930 fps | 100% |
| Accurate 8700 | <<locked>> | 90% | 40,030 psi | 60% | 2776 fps | 95.1% |
| Accurate MAGPRO | <<locked>> | 80% | 56,014 psi | 84% | 3104 fps | 99.9% |
| ADI AR 2213 | <<locked>> | 80% | 52,562 psi | 79% | 3031 fps | 100% |
| ADI AR 2217 | <<locked>> | 80% | 39,682 psi | 59% | 2776 fps | 98.8% |
| ADI AR 2218 | 93.3 gr | 84% | 39,639 psi | 59% | 2851 fps | 95.5% |
| ADI AR 2225 | <<locked>> | 80% | 37,144 psi | 56% | 2749 fps | 99.9% |
| Alliant Reloder-22 | <<locked>> | 80% | 53,287 psi | 80% | 3025 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 80% | 51,967 psi | 78% | 2933 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 46,253 psi | 69% | 2904 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 82% | 41,365 psi | 62% | 2848 fps | 96% |
| Alliant Reloder-50 | 97 gr | 86% | 41,916 psi | 63% | 2848 fps | 95.6% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 49,472 psi | 74% | 2933 fps | 98.5% |
| Bofors RP15 | <<locked>> | 80% | 49,647 psi | 74% | 2963 fps | 100% |
| Bofors RP30 | <<locked>> | 80% | 43,163 psi | 65% | 2854 fps | 99.4% |
| Bofors RP5 | <<locked>> | 80% | 53,287 psi | 80% | 3025 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 43,294 psi | 65% | 2851 fps | 99.7% |
| Hodgdon H4831 | <<locked>> | 80% | 54,737 psi | 82% | 3022 fps | 99.9% |
| Hodgdon H4831 SC | <<locked>> | 80% | 53,693 psi | 80% | 3005 fps | 99.9% |
| Hodgdon Retumbo | <<locked>> | 80% | 45,803 psi | 69% | 2982 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,732 psi | 43% | 1798 fps | 100% |
| Hodgdon US 869 | <<locked>> | 96% | 54,418 psi | 82% | 3041 fps | 95.1% |
| IMR 4955 Enduron | <<locked>> | 80% | 54,679 psi | 82% | 2995 fps | 100% |
| IMR 7828 SSC | <<locked>> | 80% | 51,517 psi | 77% | 3018 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 84% | 50,067 psi | 75% | 2890 fps | 95.6% |
| IMR 8133 Enduron | <<locked>> | 80% | 34,592 psi | 52% | 2667 fps | 97.1% |
| Lovex D100 | <<locked>> | 90% | 55,071 psi | 83% | 3005 fps | 95.9% |
| Lovex S071 | <<locked>> | 80% | 45,803 psi | 69% | 2808 fps | 100% |
| Norma 217 | <<locked>> | 80% | 35,404 psi | 53% | 2697 fps | 99.1% |
| Ramshot Grand | <<locked>> | 80% | 52,765 psi | 79% | 3041 fps | 100% |
| Ramshot LRT | <<locked>> | 92% | 53,185 psi | 80% | 3081 fps | 95% |
| Ramshot Magnum | <<locked>> | 80% | 47,630 psi | 71% | 2900 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,646 psi | 44% | 1844 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 45,818 psi | 69% | 2956 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 42,003 psi | 63% | 2851 fps | 98.2% |
| Shooters World 50 BMG | <<locked>> | 90% | 55,071 psi | 83% | 3005 fps | 95.9% |
| SNPE Vectan SP 13 | <<locked>> | 90% | 42,134 psi | 63% | 2799 fps | 95.4% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 56,463 psi | 85% | 3051 fps | 100% |
| Vihtavuori 20N29 | <<locked>> | 98% | 49,037 psi | 74% | 2953 fps | 95.9% |
| Vihtavuori 24N41 | <<locked>> | 94% | 54,839 psi | 82% | 3051 fps | 95.2% |
| Vihtavuori N165 | <<locked>> | 80% | 50,198 psi | 75% | 2897 fps | 100% |
| Vihtavuori N170 | <<locked>> | 80% | 43,395 psi | 65% | 2795 fps | 95.2% |
| Vihtavuori N565 | <<locked>> | 80% | 47,659 psi | 71% | 2927 fps | 99.6% |
| Vihtavuori N568 | <<locked>> | 80% | 42,757 psi | 64% | 2864 fps | 97.9% |
| Vihtavuori N570 | 87 gr | 80% | 40,843 psi | 61% | 2854 fps | 95.3% |
| Winchester StaBALL HD | <<locked>> | 80% | 53,229 psi | 80% | 3025 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 52,982 psi | 79% | 2956 fps | 100% |
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 48 powders for 7.21 Firebird loaded with the .284 | 160gr | Speer Deep Curl Soft Point. ADI AR 2218 delivers the highest muzzle velocity at 3,232 fps; across all powders the maximum-charge window runs from 2,005 fps to 3,232 fps. Accurate 8700 gives the best case fill at 100 %, and 48 of the 48 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 160.0 gr projectile in 0.284" calls for a 1:12.5 twist; slower twists will usually not stabilise this weight. Accurate 8700, Hodgdon TrailBoss, 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. ADI AR 2218, Vihtavuori N570, Alliant Reloder-50 rank at the top here: for 7.21 Firebird with the .284 | 160gr | Speer Deep Curl Soft Point they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Hodgdon 50BMG 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.