Load Specifications
Load data in caliber 7.21 Firebird with .284 | 150gr | Barnes X BT bullet and 46 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.
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Max Load - Barrel Length: 26"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 3100 | <<locked>> | 82% | 57,493 psi | 86% | 3064 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 57,464 psi | 86% | 3173 fps | 98.8% |
| Accurate MAGPRO | <<locked>> | 82% | 59,988 psi | 90% | 3238 fps | 99.9% |
| ADI AR 2213 | <<locked>> | 84% | 59,930 psi | 90% | 3225 fps | 100% |
| ADI AR 2217 | <<locked>> | 92% | 59,973 psi | 90% | 3212 fps | 100% |
| ADI AR 2218 | <<locked>> | 94% | 57,043 psi | 86% | 3294 fps | 99.4% |
| ADI AR 2225 | <<locked>> | 94% | 60,321 psi | 90% | 3238 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 82% | 60,307 psi | 90% | 3189 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 82% | 57,000 psi | 85% | 3163 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 84% | 59,306 psi | 89% | 3117 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 86% | 56,507 psi | 85% | 3146 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 92% | 59,741 psi | 90% | 3274 fps | 99.4% |
| Alliant Reloder-50 | <<locked>> | 94% | 56,913 psi | 85% | 3212 fps | 98.7% |
| Baschieri & Pellagri 109 | <<locked>> | 86% | 59,408 psi | 89% | 3176 fps | 99.4% |
| Bofors RP15 | <<locked>> | 86% | 60,365 psi | 90% | 3215 fps | 100% |
| Bofors RP30 | <<locked>> | 88% | 56,898 psi | 85% | 3176 fps | 100% |
| Bofors RP5 | <<locked>> | 82% | 57,000 psi | 85% | 3163 fps | 100% |
| Hodgdon H1000 | <<locked>> | 88% | 57,450 psi | 86% | 3173 fps | 100% |
| Hodgdon H4831 | <<locked>> | 82% | 58,305 psi | 87% | 3150 fps | 99.9% |
| Hodgdon H4831 SC | <<locked>> | 82% | 57,232 psi | 86% | 3133 fps | 99.9% |
| Hodgdon Retumbo | <<locked>> | 86% | 56,318 psi | 84% | 3248 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,377 psi | 58% | 2060 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 82% | 58,073 psi | 87% | 3120 fps | 100% |
| IMR 7828 SSC | <<locked>> | 84% | 58,697 psi | 88% | 3212 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 88% | 56,840 psi | 85% | 3071 fps | 96.4% |
| IMR 8133 Enduron | <<locked>> | 96% | 59,567 psi | 89% | 3235 fps | 100% |
| Lovex D100 | <<locked>> | 92% | 59,074 psi | 89% | 3133 fps | 95.9% |
| Lovex S071 | <<locked>> | 88% | 59,799 psi | 90% | 3097 fps | 100% |
| Norma 217 | <<locked>> | 94% | 57,754 psi | 87% | 3202 fps | 100% |
| Ramshot Grand | <<locked>> | 82% | 56,492 psi | 85% | 3176 fps | 100% |
| Ramshot Magnum | <<locked>> | 86% | 59,393 psi | 89% | 3159 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,407 psi | 59% | 2106 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 86% | 57,246 psi | 86% | 3228 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 88% | 56,768 psi | 85% | 3205 fps | 99.9% |
| Shooters World 50 BMG | <<locked>> | 92% | 59,074 psi | 89% | 3133 fps | 95.9% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 59,248 psi | 89% | 3179 fps | 98.7% |
| SNPE Vectan Tubal 8000 | <<locked>> | 82% | 60,249 psi | 90% | 3182 fps | 100% |
| Vihtavuori 20N29ᴾ | <<locked>> | 100% | 52,924 psi | 79% | 3091 fps | 96.2% |
| Vihtavuori N165 | <<locked>> | 84% | 57,377 psi | 86% | 3081 fps | 100% |
| Vihtavuori N170 | <<locked>> | 88% | 57,246 psi | 86% | 3120 fps | 97.9% |
| Vihtavuori N560 | <<locked>> | 82% | 60,307 psi | 90% | 3245 fps | 100% |
| Vihtavuori N565 | <<locked>> | 86% | 58,682 psi | 88% | 3192 fps | 100% |
| Vihtavuori N568 | <<locked>> | 88% | 56,898 psi | 85% | 3205 fps | 99.7% |
| Vihtavuori N570 | <<locked>> | 90% | 58,392 psi | 88% | 3278 fps | 99% |
| Winchester StaBALL HD | <<locked>> | 82% | 57,493 psi | 86% | 3166 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 82% | 56,753 psi | 85% | 3087 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% | 54,056 psi | 81% | 3015 fps | 100% |
| Accurate 8700 | <<locked>> | 92% | 43,511 psi | 65% | 2913 fps | 95.6% |
| Accurate MAGPRO | <<locked>> | 80% | 56,043 psi | 84% | 3176 fps | 99.7% |
| ADI AR 2213 | <<locked>> | 80% | 52,576 psi | 79% | 3104 fps | 99.8% |
| ADI AR 2217 | <<locked>> | 80% | 40,205 psi | 60% | 2851 fps | 98.5% |
| ADI AR 2218 | 94 gr | 86% | 43,062 psi | 65% | 2999 fps | 96% |
| ADI AR 2225 | <<locked>> | 80% | 37,782 psi | 57% | 2835 fps | 99.8% |
| Alliant Reloder-19 | <<locked>> | 80% | 56,768 psi | 85% | 3133 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 53,592 psi | 80% | 3107 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 80% | 52,359 psi | 78% | 3015 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 46,499 psi | 70% | 2982 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 82% | 41,901 psi | 63% | 2927 fps | 95.5% |
| Alliant Reloder-50 | 95.4 gr | 86% | 43,134 psi | 65% | 2943 fps | 95.4% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 49,168 psi | 74% | 2992 fps | 97.9% |
| Bofors RP15 | <<locked>> | 80% | 50,082 psi | 75% | 3041 fps | 99.9% |
| Bofors RP30 | <<locked>> | 80% | 43,976 psi | 66% | 2940 fps | 99.2% |
| Bofors RP5 | <<locked>> | 80% | 53,592 psi | 80% | 3107 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 43,642 psi | 65% | 2927 fps | 99.5% |
| Hodgdon H4831 | <<locked>> | 80% | 54,621 psi | 82% | 3087 fps | 99.8% |
| Hodgdon H4831 SC | <<locked>> | 80% | 53,766 psi | 81% | 3074 fps | 99.7% |
| Hodgdon Retumbo | <<locked>> | 80% | 45,774 psi | 69% | 3061 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,979 psi | 43% | 1850 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 54,520 psi | 82% | 3061 fps | 99.8% |
| IMR 7828 SSC | <<locked>> | 80% | 51,416 psi | 77% | 3091 fps | 99.8% |
| IMR 7977 Enduron | <<locked>> | 86% | 53,505 psi | 80% | 3015 fps | 95.7% |
| IMR 8133 Enduron | <<locked>> | 80% | 35,723 psi | 54% | 2759 fps | 96.9% |
| Lovex D100 | <<locked>> | 90% | 54,969 psi | 82% | 3064 fps | 95% |
| Lovex S071 | <<locked>> | 80% | 47,036 psi | 71% | 2894 fps | 100% |
| Norma 217 | <<locked>> | 80% | 36,477 psi | 55% | 2792 fps | 99% |
| Ramshot Grand | <<locked>> | 80% | 52,678 psi | 79% | 3114 fps | 100% |
| Ramshot Magnum | <<locked>> | 80% | 48,109 psi | 72% | 2982 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,805 psi | 45% | 1893 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 45,934 psi | 69% | 3038 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 42,743 psi | 64% | 2940 fps | 97.9% |
| Shooters World 50 BMG | <<locked>> | 90% | 54,969 psi | 82% | 3064 fps | 95% |
| SNPE Vectan SP 13 | <<locked>> | 92% | 45,701 psi | 69% | 2936 fps | 95.9% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 56,434 psi | 85% | 3123 fps | 100% |
| Vihtavuori 20N29 | <<locked>> | 98% | 49,545 psi | 74% | 3028 fps | 95.2% |
| Vihtavuori N165 | <<locked>> | 80% | 50,618 psi | 76% | 2972 fps | 100% |
| Vihtavuori N170 | <<locked>> | 82% | 47,311 psi | 71% | 2940 fps | 95.7% |
| Vihtavuori N560 | <<locked>> | 80% | 56,362 psi | 84% | 3182 fps | 99.9% |
| Vihtavuori N565 | <<locked>> | 80% | 48,443 psi | 73% | 3009 fps | 99.4% |
| Vihtavuori N568 | <<locked>> | 80% | 43,439 psi | 65% | 2946 fps | 97.5% |
| Vihtavuori N570 | 87.8 gr | 82% | 44,541 psi | 67% | 3009 fps | 95.9% |
| Winchester StaBALL HD | <<locked>> | 80% | 53,432 psi | 80% | 3107 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 53,142 psi | 80% | 3028 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 46 powders for 7.21 Firebird loaded with the .284 | 150gr | Barnes X BT. ADI AR 2218 delivers the highest muzzle velocity at 3,294 fps; across all powders the maximum-charge window runs from 2,060 fps to 3,294 fps. Accurate 8700 gives the best case fill at 100 %, and 46 of the 46 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (460 MPa), the top charges use 58–90 %, leaving at least 10 % headroom. The 150.0 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, Alliant Reloder-50 rank at the top here: for 7.21 Firebird with the .284 | 150gr | Barnes X BT 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.