Load Specifications
Load data in caliber 7.21 Firebird with .284 | 142gr | Lehigh Defense Controlled Chaos bullet and 52 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>> | 86% | 58,407 psi | 88% | 3163 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 50,357 psi | 75% | 3120 fps | 96.9% |
| Accurate MAGPRO | <<locked>> | 84% | 57,522 psi | 86% | 3278 fps | 99.6% |
| ADI AR 2209 | <<locked>> | 84% | 59,234 psi | 89% | 3258 fps | 100% |
| ADI AR 2213 | <<locked>> | 86% | 58,059 psi | 87% | 3278 fps | 100% |
| ADI AR 2217 | <<locked>> | 94% | 57,638 psi | 86% | 3255 fps | 100% |
| ADI AR 2218 | <<locked>> | 98% | 58,595 psi | 88% | 3392 fps | 99.2% |
| ADI AR 2225 | <<locked>> | 96% | 57,261 psi | 86% | 3278 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 84% | 58,653 psi | 88% | 3241 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 86% | 58,581 psi | 88% | 3268 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 86% | 56,869 psi | 85% | 3166 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 90% | 57,769 psi | 87% | 3248 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 82% | 57,841 psi | 87% | 3258 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 94% | 56,521 psi | 85% | 3291 fps | 98.6% |
| Alliant Reloder-50 | <<locked>> | 98% | 56,550 psi | 85% | 3281 fps | 98.2% |
| Baschieri & Pellagri 109 | <<locked>> | 88% | 58,320 psi | 87% | 3228 fps | 98.9% |
| Bofors RP15 | <<locked>> | 88% | 57,943 psi | 87% | 3258 fps | 100% |
| Bofors RP30 | <<locked>> | 92% | 57,580 psi | 86% | 3271 fps | 100% |
| Bofors RP5 | <<locked>> | 86% | 58,581 psi | 88% | 3268 fps | 100% |
| Hodgdon H1000 | <<locked>> | 92% | 59,088 psi | 89% | 3274 fps | 100% |
| Hodgdon H4831 | <<locked>> | 84% | 56,666 psi | 85% | 3199 fps | 99.7% |
| Hodgdon H4831 SC | <<locked>> | 86% | 59,509 psi | 89% | 3245 fps | 99.9% |
| Hodgdon Hybrid 100V | <<locked>> | 82% | 59,335 psi | 89% | 3150 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 90% | 57,145 psi | 86% | 3343 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,971 psi | 57% | 2106 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 84% | 56,811 psi | 85% | 3176 fps | 99.8% |
| IMR 7828 SSC | <<locked>> | 86% | 56,724 psi | 85% | 3261 fps | 99.9% |
| IMR 7977 Enduron | <<locked>> | 92% | 59,292 psi | 89% | 3182 fps | 96.3% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 60,017 psi | 90% | 3320 fps | 100% |
| Lovex S071 | <<locked>> | 90% | 56,724 psi | 85% | 3136 fps | 100% |
| Norma 217 | <<locked>> | 98% | 57,696 psi | 86% | 3281 fps | 100% |
| Norma MRP | <<locked>> | 84% | 59,001 psi | 88% | 3287 fps | 100% |
| Ramshot Grand | <<locked>> | 86% | 58,189 psi | 87% | 3284 fps | 100% |
| Ramshot Magnum | <<locked>> | 88% | 56,840 psi | 85% | 3202 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,885 psi | 58% | 2152 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 90% | 58,378 psi | 88% | 3327 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 92% | 57,537 psi | 86% | 3294 fps | 99.8% |
| Rottweil R 904 | <<locked>> | 84% | 59,321 psi | 89% | 3222 fps | 100% |
| Rottweil R 905 | <<locked>> | 84% | 58,668 psi | 88% | 3238 fps | 100% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 52,315 psi | 78% | 3133 fps | 97% |
| SNPE Vectan Tubal 8000 | <<locked>> | 84% | 58,291 psi | 87% | 3235 fps | 100% |
| Somchem S361 | <<locked>> | 82% | 57,043 psi | 86% | 3146 fps | 99.7% |
| Somchem S385 | <<locked>> | 84% | 58,958 psi | 88% | 3202 fps | 100% |
| Vihtavuori N165 | <<locked>> | 88% | 59,059 psi | 89% | 3186 fps | 100% |
| Vihtavuori N170 | <<locked>> | 92% | 58,755 psi | 88% | 3219 fps | 97.7% |
| Vihtavuori N555 | <<locked>> | 84% | 58,552 psi | 88% | 3199 fps | 100% |
| Vihtavuori N560 | <<locked>> | 84% | 58,247 psi | 87% | 3291 fps | 99.9% |
| Vihtavuori N565 | <<locked>> | 90% | 59,567 psi | 89% | 3284 fps | 100% |
| Vihtavuori N568 | <<locked>> | 92% | 57,885 psi | 87% | 3301 fps | 99.6% |
| Vihtavuori N570 | <<locked>> | 94% | 59,466 psi | 89% | 3369 fps | 98.7% |
| Winchester StaBALL HD | <<locked>> | 86% | 57,928 psi | 87% | 3261 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 86% | 58,958 psi | 88% | 3199 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% | 47,732 psi | 72% | 2989 fps | 100% |
| Accurate 8700 | <<locked>> | 98% | 46,586 psi | 70% | 3045 fps | 95.8% |
| Accurate MAGPRO | <<locked>> | 80% | 49,951 psi | 75% | 3140 fps | 98.7% |
| ADI AR 2209 | <<locked>> | 80% | 51,692 psi | 77% | 3130 fps | 99.9% |
| ADI AR 2213 | <<locked>> | 80% | 46,963 psi | 70% | 3074 fps | 98.9% |
| ADI AR 2217 | <<locked>> | 80% | 35,114 psi | 53% | 2792 fps | 96.1% |
| ADI AR 2218 | 97.7 gr | 90% | 43,323 psi | 65% | 3071 fps | 95.2% |
| ADI AR 2225 | <<locked>> | 80% | 32,445 psi | 49% | 2759 fps | 98% |
| Alliant Reloder-19 | <<locked>> | 80% | 51,576 psi | 77% | 3123 fps | 99.9% |
| Alliant Reloder-22 | <<locked>> | 80% | 47,732 psi | 72% | 3077 fps | 99.7% |
| Alliant Reloder-23 | <<locked>> | 80% | 46,557 psi | 70% | 3002 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 40,669 psi | 61% | 2946 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 80% | 53,635 psi | 80% | 3192 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 88% | 44,918 psi | 67% | 3068 fps | 95.8% |
| Alliant Reloder-50 | <<locked>> | 92% | 45,121 psi | 68% | 3054 fps | 95.3% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 44,802 psi | 67% | 2972 fps | 96.1% |
| Bofors RP15 | <<locked>> | 80% | 44,527 psi | 67% | 3009 fps | 99.2% |
| Bofors RP30 | <<locked>> | 80% | 38,087 psi | 57% | 2877 fps | 97.2% |
| Bofors RP5 | <<locked>> | 80% | 47,732 psi | 72% | 3077 fps | 99.7% |
| Hodgdon H1000 | <<locked>> | 80% | 38,305 psi | 57% | 2877 fps | 97.9% |
| Hodgdon H4831 | <<locked>> | 80% | 49,472 psi | 74% | 3071 fps | 98.9% |
| Hodgdon H4831 SC | <<locked>> | 80% | 48,472 psi | 73% | 3051 fps | 98.7% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 55,535 psi | 83% | 3097 fps | 100% |
| Hodgdon Retumbo | 82 gr | 80% | 39,769 psi | 60% | 3002 fps | 99.2% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,485 psi | 43% | 1890 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 49,922 psi | 75% | 3054 fps | 99.1% |
| IMR 7828 SSC | <<locked>> | 80% | 45,818 psi | 69% | 3058 fps | 98.8% |
| IMR 7977 Enduron | <<locked>> | 90% | 55,608 psi | 83% | 3120 fps | 95.5% |
| IMR 8133 Enduron | <<locked>> | 84% | 34,621 psi | 52% | 2802 fps | 95.7% |
| Lovex S071 | <<locked>> | 80% | 41,017 psi | 61% | 2858 fps | 99.8% |
| Norma 217 | <<locked>> | 80% | 30,313 psi | 45% | 2697 fps | 96% |
| Norma MRP | <<locked>> | 80% | 51,126 psi | 77% | 3156 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 46,470 psi | 70% | 3074 fps | 99.1% |
| Ramshot Magnum | <<locked>> | 80% | 41,989 psi | 63% | 2936 fps | 99.4% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,240 psi | 44% | 1932 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 39,508 psi | 59% | 2976 fps | 99.7% |
| ReloadSwiss RS 80 | <<locked>> | 82% | 39,320 psi | 59% | 2930 fps | 96.1% |
| Rottweil R 904 | <<locked>> | 80% | 52,127 psi | 78% | 3100 fps | 99.6% |
| Rottweil R 905 | <<locked>> | 80% | 51,227 psi | 77% | 3114 fps | 99.9% |
| SNPE Vectan SP 13 | <<locked>> | 96% | 45,426 psi | 68% | 2999 fps | 95% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 50,879 psi | 76% | 3110 fps | 99.9% |
| Somchem S361 | <<locked>> | 80% | 53,447 psi | 80% | 3087 fps | 99.4% |
| Somchem S385 | <<locked>> | 80% | 51,561 psi | 77% | 3081 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 45,368 psi | 68% | 2953 fps | 99.6% |
| Vihtavuori N170 | <<locked>> | 86% | 47,863 psi | 72% | 3018 fps | 95.1% |
| Vihtavuori N555 | <<locked>> | 80% | 51,401 psi | 77% | 3087 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 50,546 psi | 76% | 3156 fps | 99.2% |
| Vihtavuori N565 | <<locked>> | 80% | 42,322 psi | 63% | 2956 fps | 97.7% |
| Vihtavuori N568 | <<locked>> | 82% | 40,277 psi | 60% | 2946 fps | 95.8% |
| Vihtavuori N570 | 91.5 gr | 86% | 44,411 psi | 67% | 3077 fps | 95.1% |
| Winchester StaBALL HD | <<locked>> | 80% | 46,151 psi | 69% | 3074 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 47,790 psi | 72% | 3009 fps | 99.6% |
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 52 powders for 7.21 Firebird loaded with the .284 | 142gr | Lehigh Defense Controlled Chaos. ADI AR 2218 delivers the highest muzzle velocity at 3,392 fps; across all powders the maximum-charge window runs from 2,106 fps to 3,392 fps. Accurate 8700 gives the best case fill at 100 %, and 52 of the 52 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 142.0 gr projectile in 0.284" calls for a 1:9.5 twist; slower twists will usually not stabilise this weight. Accurate 8700, 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. ADI AR 2218, Hodgdon Retumbo, Vihtavuori N570 rank at the top here: for 7.21 Firebird with the .284 | 142gr | Lehigh Defense Controlled Chaos 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.