Load Specifications
Load data in caliber 7.21 Firebird with .284 | 160gr | Barnes TSX FB bullet and 54 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are ADI AR 2218, Hodgdon Retumbo and Vihtavuori N570.
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% | 57,217 psi | 86% | 2995 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 54,099 psi | 81% | 3054 fps | 98.7% |
| Accurate MAGPRO | <<locked>> | 82% | 56,768 psi | 85% | 3117 fps | 99.9% |
| ADI AR 2209 | <<locked>> | 82% | 58,262 psi | 87% | 3091 fps | 100% |
| ADI AR 2213 | <<locked>> | 84% | 57,363 psi | 86% | 3114 fps | 100% |
| ADI AR 2217 | <<locked>> | 92% | 57,334 psi | 86% | 3100 fps | 100% |
| ADI AR 2218 | <<locked>> | 96% | 58,392 psi | 88% | 3245 fps | 99.8% |
| ADI AR 2225 | <<locked>> | 94% | 57,145 psi | 86% | 3120 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 82% | 57,899 psi | 87% | 3077 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 84% | 57,812 psi | 87% | 3104 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 86% | 59,901 psi | 90% | 3051 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 88% | 57,377 psi | 86% | 3084 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 92% | 56,057 psi | 84% | 3143 fps | 99.3% |
| Alliant Reloder-50 | <<locked>> | 96% | 56,260 psi | 84% | 3136 fps | 99% |
| Baschieri & Pellagri 109 | <<locked>> | 86% | 57,421 psi | 86% | 3074 fps | 99.5% |
| Bofors RP15 | <<locked>> | 86% | 57,392 psi | 86% | 3097 fps | 100% |
| Bofors RP30 | <<locked>> | 90% | 57,145 psi | 86% | 3110 fps | 100% |
| Bofors RP5 | <<locked>> | 84% | 57,812 psi | 87% | 3104 fps | 100% |
| Hodgdon H1000 | <<locked>> | 90% | 58,769 psi | 88% | 3120 fps | 100% |
| Hodgdon H4831 | <<locked>> | 84% | 59,770 psi | 90% | 3100 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 84% | 58,595 psi | 88% | 3084 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 88% | 57,276 psi | 86% | 3186 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,029 psi | 57% | 1995 fps | 100% |
| Hodgdon US 869ᴾ | <<locked>> | 100% | 59,001 psi | 88% | 3123 fps | 96.1% |
| IMR 4955 Enduron | <<locked>> | 84% | 59,379 psi | 89% | 3071 fps | 100% |
| IMR 7828 SSC | <<locked>> | 86% | 60,118 psi | 90% | 3159 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 90% | 58,305 psi | 87% | 3031 fps | 97.3% |
| IMR 8133 Enduron | <<locked>> | 98% | 59,886 psi | 90% | 3166 fps | 100% |
| Lovex D100 | <<locked>> | 94% | 59,988 psi | 90% | 3087 fps | 96.7% |
| Lovex S071 | <<locked>> | 90% | 59,379 psi | 89% | 3025 fps | 100% |
| Norma 217 | <<locked>> | 96% | 57,638 psi | 86% | 3127 fps | 100% |
| Norma MRP | <<locked>> | 82% | 58,160 psi | 87% | 3117 fps | 100% |
| Ramshot Grand | <<locked>> | 84% | 57,551 psi | 86% | 3120 fps | 100% |
| Ramshot Magnum | <<locked>> | 86% | 55,941 psi | 84% | 3041 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,131 psi | 59% | 2041 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 88% | 58,189 psi | 87% | 3166 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 90% | 57,101 psi | 86% | 3143 fps | 100% |
| Rottweil R 904 | <<locked>> | 82% | 58,363 psi | 87% | 3058 fps | 100% |
| Rottweil R 905 | <<locked>> | 82% | 57,638 psi | 86% | 3068 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 94% | 59,988 psi | 90% | 3087 fps | 96.7% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 55,637 psi | 83% | 3061 fps | 98.6% |
| SNPE Vectan Tubal 8000 | <<locked>> | 82% | 57,276 psi | 86% | 3068 fps | 100% |
| Somchem S361 | <<locked>> | 82% | 59,843 psi | 90% | 3048 fps | 100% |
| Somchem S385 | <<locked>> | 82% | 57,870 psi | 87% | 3035 fps | 100% |
| Vihtavuori 24N41 | <<locked>> | 98% | 59,683 psi | 89% | 3136 fps | 96.1% |
| Vihtavuori N165 | <<locked>> | 86% | 58,160 psi | 87% | 3025 fps | 100% |
| Vihtavuori N170 | <<locked>> | 90% | 57,667 psi | 86% | 3064 fps | 98.4% |
| Vihtavuori N555 | <<locked>> | 82% | 57,479 psi | 86% | 3028 fps | 100% |
| Vihtavuori N560 | <<locked>> | 82% | 57,421 psi | 86% | 3127 fps | 100% |
| Vihtavuori N565 | <<locked>> | 88% | 58,987 psi | 88% | 3127 fps | 100% |
| Vihtavuori N568 | <<locked>> | 90% | 57,319 psi | 86% | 3143 fps | 99.9% |
| Vihtavuori N570 | <<locked>> | 92% | 59,074 psi | 89% | 3219 fps | 99.4% |
| Winchester StaBALL HD | <<locked>> | 84% | 57,841 psi | 87% | 3097 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 84% | 57,798 psi | 87% | 3035 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% | 49,835 psi | 75% | 2884 fps | 100% |
| Accurate 8700 | <<locked>> | 94% | 42,960 psi | 64% | 2844 fps | 96% |
| Accurate MAGPRO | <<locked>> | 80% | 52,736 psi | 79% | 3051 fps | 99.7% |
| ADI AR 2209 | <<locked>> | 80% | 54,462 psi | 82% | 3031 fps | 100% |
| ADI AR 2213 | <<locked>> | 80% | 49,777 psi | 75% | 2986 fps | 99.8% |
| ADI AR 2217 | <<locked>> | 80% | 37,173 psi | 56% | 2720 fps | 98.1% |
| ADI AR 2218 | 92.7 gr | 86% | 39,755 psi | 60% | 2861 fps | 95.3% |
| ADI AR 2225 | <<locked>> | 80% | 34,418 psi | 52% | 2690 fps | 99.5% |
| Alliant Reloder-19 | <<locked>> | 80% | 54,056 psi | 81% | 3018 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 50,401 psi | 76% | 2982 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 80% | 49,110 psi | 74% | 2894 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 43,308 psi | 65% | 2854 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 84% | 41,205 psi | 62% | 2851 fps | 95.8% |
| Alliant Reloder-50 | <<locked>> | 88% | 41,379 psi | 62% | 2841 fps | 95.2% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 47,036 psi | 71% | 2890 fps | 97.8% |
| Bofors RP15 | <<locked>> | 80% | 46,963 psi | 70% | 2917 fps | 99.9% |
| Bofors RP30 | <<locked>> | 80% | 40,205 psi | 60% | 2799 fps | 98.8% |
| Bofors RP5 | <<locked>> | 80% | 50,401 psi | 76% | 2982 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 40,538 psi | 61% | 2799 fps | 99.3% |
| Hodgdon H4831 | <<locked>> | 80% | 52,083 psi | 78% | 2979 fps | 99.8% |
| Hodgdon H4831 SC | <<locked>> | 80% | 51,053 psi | 77% | 2963 fps | 99.7% |
| Hodgdon Retumbo | 81.4 gr | 80% | 42,583 psi | 64% | 2927 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,587 psi | 43% | 1788 fps | 100% |
| Hodgdon US 869 | <<locked>> | 98% | 54,781 psi | 82% | 3054 fps | 95.1% |
| IMR 4955 Enduron | <<locked>> | 80% | 52,257 psi | 78% | 2956 fps | 99.8% |
| IMR 7828 SSC | <<locked>> | 80% | 48,617 psi | 73% | 2969 fps | 99.7% |
| IMR 7977 Enduron | <<locked>> | 86% | 51,140 psi | 77% | 2910 fps | 95.7% |
| IMR 8133 Enduron | <<locked>> | 80% | 31,850 psi | 48% | 2598 fps | 95.7% |
| Lovex D100 | <<locked>> | 92% | 55,927 psi | 84% | 3022 fps | 95.8% |
| Lovex S071 | <<locked>> | 80% | 42,830 psi | 64% | 2759 fps | 100% |
| Norma 217 | <<locked>> | 80% | 32,358 psi | 49% | 2628 fps | 98.1% |
| Norma MRP | <<locked>> | 80% | 54,186 psi | 81% | 3054 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 49,647 psi | 74% | 2992 fps | 99.9% |
| Ramshot Magnum | <<locked>> | 80% | 44,541 psi | 67% | 2851 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,341 psi | 44% | 1831 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 42,380 psi | 64% | 2900 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 38,740 psi | 58% | 2782 fps | 97.1% |
| Rottweil R 904 | <<locked>> | 80% | 54,650 psi | 82% | 3002 fps | 100% |
| Rottweil R 905 | <<locked>> | 80% | 53,896 psi | 81% | 3012 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 92% | 55,927 psi | 84% | 3022 fps | 95.8% |
| SNPE Vectan SP 13 | <<locked>> | 92% | 41,901 psi | 63% | 2799 fps | 95.2% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 53,548 psi | 80% | 3009 fps | 100% |
| Somchem S361 | <<locked>> | 80% | 55,854 psi | 84% | 2989 fps | 99.9% |
| Somchem S385 | <<locked>> | 80% | 54,056 psi | 81% | 2976 fps | 100% |
| Vihtavuori 24N41 | <<locked>> | 96% | 55,506 psi | 83% | 3068 fps | 95.2% |
| Vihtavuori N165 | <<locked>> | 80% | 47,514 psi | 71% | 2854 fps | 100% |
| Vihtavuori N170 | <<locked>> | 82% | 43,801 psi | 66% | 2808 fps | 95.2% |
| Vihtavuori N555 | <<locked>> | 80% | 53,954 psi | 81% | 2976 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 53,519 psi | 80% | 3064 fps | 99.9% |
| Vihtavuori N565 | <<locked>> | 80% | 44,556 psi | 67% | 2874 fps | 99.1% |
| Vihtavuori N568 | <<locked>> | 80% | 39,726 psi | 60% | 2802 fps | 96.9% |
| Vihtavuori N570 | 86.6 gr | 82% | 40,901 psi | 61% | 2864 fps | 95.2% |
| Winchester StaBALL HD | <<locked>> | 80% | 49,603 psi | 74% | 2976 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 50,314 psi | 75% | 2917 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 57 powders for 7.21 Firebird loaded with the .284 | 160gr | Barnes TSX FB. ADI AR 2218 delivers the highest muzzle velocity at 3,245 fps; across all powders the maximum-charge window runs from 1,995 fps to 3,245 fps. Accurate 8700 gives the best case fill at 100 %, and 57 of the 57 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 1:10.0 twist; slower twists will usually not stabilise this weight. Accurate 8700, Hodgdon TrailBoss, Hodgdon US 869 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, Hodgdon Retumbo, Vihtavuori N570 rank at the top here: for 7.21 Firebird with the .284 | 160gr | Barnes TSX FB 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.