Load Specifications
Load data in caliber 7.21 Firebird with .284 | 160gr | Nosler AccuBond bullet and 53 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 IMR 8133 Enduron.
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>> | 84% | 59,059 psi | 89% | 3015 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 55,840 psi | 84% | 3081 fps | 99% |
| Accurate MAGPRO | <<locked>> | 82% | 58,407 psi | 88% | 3143 fps | 100% |
| ADI AR 2209 | <<locked>> | 82% | 59,669 psi | 89% | 3107 fps | 100% |
| ADI AR 2213 | <<locked>> | 84% | 58,827 psi | 88% | 3133 fps | 100% |
| ADI AR 2217 | <<locked>> | 92% | 58,885 psi | 88% | 3123 fps | 100% |
| ADI AR 2218 | <<locked>> | 96% | 60,075 psi | 90% | 3274 fps | 99.9% |
| ADI AR 2225 | <<locked>> | 94% | 58,856 psi | 88% | 3140 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 82% | 59,103 psi | 89% | 3094 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 84% | 59,379 psi | 89% | 3123 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 84% | 57,667 psi | 86% | 3018 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 88% | 58,827 psi | 88% | 3100 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 92% | 57,841 psi | 87% | 3169 fps | 99.5% |
| Alliant Reloder-50 | <<locked>> | 96% | 58,407 psi | 88% | 3169 fps | 99.3% |
| Baschieri & Pellagri 109 | <<locked>> | 86% | 58,566 psi | 88% | 3091 fps | 99.6% |
| Bofors RP15 | <<locked>> | 86% | 58,755 psi | 88% | 3117 fps | 100% |
| Bofors RP30 | <<locked>> | 90% | 58,726 psi | 88% | 3133 fps | 100% |
| Bofors RP5 | <<locked>> | 84% | 59,379 psi | 89% | 3123 fps | 100% |
| Hodgdon H1000 | <<locked>> | 90% | 60,133 psi | 90% | 3136 fps | 100% |
| Hodgdon H4831 | <<locked>> | 82% | 57,116 psi | 86% | 3058 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 84% | 59,988 psi | 90% | 3104 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 88% | 59,030 psi | 88% | 3209 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,087 psi | 57% | 1995 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 82% | 56,971 psi | 85% | 3031 fps | 100% |
| IMR 7828 SSC | <<locked>> | 84% | 57,464 psi | 86% | 3117 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 90% | 59,538 psi | 89% | 3051 fps | 97.5% |
| IMR 8133 Enduron | <<locked>> | 96% | 57,696 psi | 86% | 3130 fps | 100% |
| Lovex D100 | <<locked>> | 92% | 57,435 psi | 86% | 3045 fps | 96.2% |
| Lovex S071 | <<locked>> | 88% | 57,551 psi | 86% | 2995 fps | 100% |
| Norma 217 | <<locked>> | 96% | 59,611 psi | 89% | 3153 fps | 100% |
| Norma MRP | <<locked>> | 82% | 59,625 psi | 89% | 3133 fps | 100% |
| Ramshot Grand | <<locked>> | 84% | 59,263 psi | 89% | 3143 fps | 100% |
| Ramshot LRT | <<locked>> | 96% | 59,321 psi | 89% | 3189 fps | 96.4% |
| Ramshot Magnum | <<locked>> | 86% | 57,682 psi | 86% | 3064 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,218 psi | 59% | 2044 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 88% | 60,031 psi | 90% | 3189 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 90% | 59,016 psi | 88% | 3169 fps | 100% |
| Rottweil R 904 | <<locked>> | 82% | 59,495 psi | 89% | 3074 fps | 100% |
| Rottweil R 905 | <<locked>> | 82% | 59,205 psi | 89% | 3091 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 92% | 57,435 psi | 86% | 3045 fps | 96.2% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 57,377 psi | 86% | 3084 fps | 98.9% |
| SNPE Vectan Tubal 8000 | <<locked>> | 82% | 58,827 psi | 88% | 3087 fps | 100% |
| Somchem S385 | <<locked>> | 82% | 59,277 psi | 89% | 3051 fps | 100% |
| Vihtavuori 20N29ᴾ | <<locked>> | 100% | 50,749 psi | 76% | 2989 fps | 96.2% |
| Vihtavuori N165 | <<locked>> | 86% | 59,654 psi | 89% | 3045 fps | 100% |
| Vihtavuori N170 | <<locked>> | 90% | 59,248 psi | 89% | 3091 fps | 98.7% |
| Vihtavuori N555 | <<locked>> | 82% | 59,277 psi | 89% | 3048 fps | 100% |
| Vihtavuori N560 | <<locked>> | 82% | 58,813 psi | 88% | 3146 fps | 100% |
| Vihtavuori N565 | <<locked>> | 86% | 56,768 psi | 85% | 3087 fps | 100% |
| Vihtavuori N568 | <<locked>> | 90% | 59,074 psi | 89% | 3169 fps | 100% |
| Vihtavuori N570 | <<locked>> | 90% | 56,710 psi | 85% | 3176 fps | 99.1% |
| Winchester StaBALL HD | <<locked>> | 84% | 59,582 psi | 89% | 3117 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 84% | 59,277 psi | 89% | 3051 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% | 51,648 psi | 77% | 2907 fps | 100% |
| Accurate 8700 | <<locked>> | 92% | 41,437 psi | 62% | 2808 fps | 95.5% |
| Accurate MAGPRO | <<locked>> | 80% | 54,389 psi | 82% | 3077 fps | 99.8% |
| ADI AR 2209 | <<locked>> | 80% | 55,680 psi | 83% | 3048 fps | 100% |
| ADI AR 2213 | <<locked>> | 80% | 51,213 psi | 77% | 3009 fps | 99.9% |
| ADI AR 2217 | <<locked>> | 80% | 38,464 psi | 58% | 2749 fps | 98.5% |
| ADI AR 2218 | 93.1 gr | 86% | 41,234 psi | 62% | 2897 fps | 96% |
| ADI AR 2225 | <<locked>> | 80% | 35,810 psi | 54% | 2723 fps | 99.7% |
| Alliant Reloder-19 | <<locked>> | 80% | 55,448 psi | 83% | 3038 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 51,938 psi | 78% | 3005 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 80% | 50,560 psi | 76% | 2913 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 44,701 psi | 67% | 2877 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 82% | 39,798 psi | 60% | 2818 fps | 95.4% |
| Alliant Reloder-50 | <<locked>> | 88% | 43,395 psi | 65% | 2884 fps | 96% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 48,167 psi | 72% | 2910 fps | 98.1% |
| Bofors RP15 | <<locked>> | 80% | 48,341 psi | 72% | 2940 fps | 100% |
| Bofors RP30 | <<locked>> | 80% | 41,872 psi | 63% | 2831 fps | 99.1% |
| Bofors RP5 | <<locked>> | 80% | 51,938 psi | 78% | 3005 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 42,018 psi | 63% | 2828 fps | 99.5% |
| Hodgdon H4831 | <<locked>> | 80% | 53,301 psi | 80% | 2995 fps | 99.8% |
| Hodgdon H4831 SC | <<locked>> | 80% | 52,446 psi | 79% | 2982 fps | 99.8% |
| Hodgdon Retumbo | <<locked>> | 80% | 44,077 psi | 66% | 2953 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,703 psi | 43% | 1791 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 53,330 psi | 80% | 2972 fps | 99.9% |
| IMR 7828 SSC | <<locked>> | 80% | 49,966 psi | 75% | 2992 fps | 99.8% |
| IMR 7977 Enduron | <<locked>> | 84% | 48,936 psi | 73% | 2867 fps | 95.1% |
| IMR 8133 Enduron | 79.5 gr | 80% | 33,388 psi | 50% | 2638 fps | 96.5% |
| Lovex D100 | <<locked>> | 90% | 53,461 psi | 80% | 2976 fps | 95.3% |
| Lovex S071 | <<locked>> | 80% | 44,614 psi | 67% | 2785 fps | 100% |
| Norma 217 | <<locked>> | 80% | 33,982 psi | 51% | 2667 fps | 98.7% |
| Norma MRP | <<locked>> | 80% | 55,637 psi | 83% | 3077 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 51,126 psi | 77% | 3015 fps | 100% |
| Ramshot LRT | <<locked>> | 94% | 55,100 psi | 83% | 3117 fps | 95.3% |
| Ramshot Magnum | <<locked>> | 80% | 46,224 psi | 69% | 2881 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,486 psi | 44% | 1831 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 44,135 psi | 66% | 2930 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 40,495 psi | 61% | 2822 fps | 97.7% |
| Rottweil R 904 | <<locked>> | 80% | 55,796 psi | 84% | 3015 fps | 100% |
| Rottweil R 905 | <<locked>> | 80% | 55,419 psi | 83% | 3031 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 90% | 53,461 psi | 80% | 2976 fps | 95.3% |
| SNPE Vectan SP 13 | <<locked>> | 92% | 43,555 psi | 65% | 2831 fps | 95.8% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 55,071 psi | 83% | 3028 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 55,622 psi | 83% | 2999 fps | 100% |
| Vihtavuori 20N29 | <<locked>> | 98% | 47,268 psi | 71% | 2923 fps | 95.2% |
| Vihtavuori N165 | <<locked>> | 80% | 48,950 psi | 73% | 2877 fps | 100% |
| Vihtavuori N170 | <<locked>> | 82% | 45,179 psi | 68% | 2835 fps | 95.7% |
| Vihtavuori N555 | <<locked>> | 80% | 55,579 psi | 83% | 2995 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 54,882 psi | 82% | 3084 fps | 100% |
| Vihtavuori N565 | <<locked>> | 80% | 46,253 psi | 69% | 2904 fps | 99.4% |
| Vihtavuori N568 | <<locked>> | 80% | 41,394 psi | 62% | 2838 fps | 97.4% |
| Vihtavuori N570 | 86.9 gr | 82% | 42,424 psi | 64% | 2897 fps | 95.8% |
| Winchester StaBALL HD | <<locked>> | 80% | 51,372 psi | 77% | 3002 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 51,590 psi | 77% | 2933 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 56 powders for 7.21 Firebird loaded with the .284 | 160gr | Nosler AccuBond. ADI AR 2218 delivers the highest muzzle velocity at 3,274 fps; across all powders the maximum-charge window runs from 1,995 fps to 3,274 fps. Accurate 8700 gives the best case fill at 100 %, and 56 of the 56 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 1:10.5 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, IMR 8133 Enduron rank at the top here: for 7.21 Firebird with the .284 | 160gr | Nosler AccuBond 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.