Load Specifications
Load data in caliber 7.21 Firebird with .284 | 145gr | CutEdge LZR MAX bullet and 53 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are Hodgdon Retumbo, ADI AR 2218 and ReloadSwiss RS 76.
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% | 56,898 psi | 85% | 3117 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 49,153 psi | 74% | 3077 fps | 96.7% |
| Accurate MAGPRO | <<locked>> | 84% | 56,478 psi | 85% | 3238 fps | 99.6% |
| ADI AR 2209 | <<locked>> | 84% | 58,334 psi | 87% | 3222 fps | 100% |
| ADI AR 2213 | <<locked>> | 86% | 57,174 psi | 86% | 3238 fps | 100% |
| ADI AR 2217 | <<locked>> | 94% | 56,550 psi | 85% | 3215 fps | 100% |
| ADI AR 2218 | <<locked>> | 98% | 57,421 psi | 86% | 3350 fps | 99.2% |
| ADI AR 2225 | <<locked>> | 98% | 60,249 psi | 90% | 3297 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 84% | 57,725 psi | 87% | 3205 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 86% | 57,551 psi | 86% | 3228 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 88% | 59,422 psi | 89% | 3179 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 90% | 56,565 psi | 85% | 3205 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 82% | 56,391 psi | 85% | 3215 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 96% | 59,393 psi | 89% | 3320 fps | 99.1% |
| Alliant Reloder-50ᴾ | <<locked>> | 100% | 59,437 psi | 89% | 3310 fps | 98.8% |
| Baschieri & Pellagri 109 | <<locked>> | 88% | 57,551 psi | 86% | 3196 fps | 98.9% |
| Bofors RP15 | <<locked>> | 88% | 56,927 psi | 85% | 3219 fps | 100% |
| Bofors RP30 | <<locked>> | 94% | 60,278 psi | 90% | 3287 fps | 100% |
| Bofors RP5 | <<locked>> | 86% | 57,551 psi | 86% | 3228 fps | 100% |
| Hodgdon H1000 | <<locked>> | 92% | 58,015 psi | 87% | 3235 fps | 100% |
| Hodgdon H4831 | <<locked>> | 86% | 59,857 psi | 90% | 3228 fps | 99.9% |
| Hodgdon H4831 SC | <<locked>> | 86% | 58,639 psi | 88% | 3209 fps | 99.9% |
| Hodgdon Hybrid 100V | <<locked>> | 82% | 58,276 psi | 87% | 3110 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 92% | 60,350 psi | 90% | 3369 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,811 psi | 57% | 2080 fps | 100% |
| IMR 4350 | <<locked>> | 82% | 60,104 psi | 90% | 3186 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 86% | 59,698 psi | 89% | 3199 fps | 99.9% |
| IMR 7828 SSC | <<locked>> | 88% | 59,611 psi | 89% | 3284 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 92% | 58,392 psi | 88% | 3146 fps | 96.2% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 58,798 psi | 88% | 3281 fps | 100% |
| Lovex S071 | <<locked>> | 92% | 59,074 psi | 89% | 3150 fps | 100% |
| Norma 217ᴾ | <<locked>> | 100% | 60,249 psi | 90% | 3297 fps | 100% |
| Norma MRP | <<locked>> | 84% | 57,740 psi | 87% | 3241 fps | 100% |
| Ramshot Grand | <<locked>> | 86% | 57,174 psi | 86% | 3245 fps | 100% |
| Ramshot Magnum | <<locked>> | 90% | 59,915 psi | 90% | 3225 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,711 psi | 58% | 2126 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 90% | 57,159 psi | 86% | 3284 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 92% | 56,260 psi | 84% | 3251 fps | 99.7% |
| Rottweil R 904 | <<locked>> | 84% | 58,436 psi | 88% | 3186 fps | 100% |
| Rottweil R 905 | <<locked>> | 84% | 57,609 psi | 86% | 3199 fps | 100% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 51,010 psi | 76% | 3091 fps | 96.8% |
| SNPE Vectan Tubal 8000 | <<locked>> | 84% | 57,232 psi | 86% | 3196 fps | 100% |
| Somchem S361 | <<locked>> | 84% | 60,191 psi | 90% | 3176 fps | 99.9% |
| Somchem S385 | <<locked>> | 84% | 57,870 psi | 87% | 3163 fps | 100% |
| Vihtavuori N165 | <<locked>> | 88% | 58,102 psi | 87% | 3150 fps | 100% |
| Vihtavuori N170 | <<locked>> | 92% | 57,421 psi | 86% | 3176 fps | 97.6% |
| Vihtavuori N555 | <<locked>> | 84% | 57,232 psi | 86% | 3156 fps | 100% |
| Vihtavuori N560 | <<locked>> | 84% | 57,058 psi | 86% | 3248 fps | 99.8% |
| Vihtavuori N565 | <<locked>> | 90% | 58,262 psi | 87% | 3241 fps | 100% |
| Vihtavuori N568 | <<locked>> | 92% | 56,492 psi | 85% | 3255 fps | 99.5% |
| Vihtavuori N570 | <<locked>> | 94% | 58,059 psi | 87% | 3327 fps | 98.6% |
| Winchester StaBALL HD | <<locked>> | 86% | 56,637 psi | 85% | 3219 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 86% | 57,827 psi | 87% | 3159 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% | 46,311 psi | 69% | 2943 fps | 100% |
| Accurate 8700 | <<locked>> | 98% | 45,324 psi | 68% | 3002 fps | 95.6% |
| Accurate MAGPRO | <<locked>> | 80% | 48,791 psi | 73% | 3097 fps | 98.6% |
| ADI AR 2209 | <<locked>> | 80% | 50,879 psi | 76% | 3094 fps | 99.9% |
| ADI AR 2213 | <<locked>> | 80% | 46,122 psi | 69% | 3035 fps | 98.9% |
| ADI AR 2217 | <<locked>> | 80% | 34,084 psi | 51% | 2746 fps | 95.8% |
| ADI AR 2218 | 96.7 gr | 90% | 42,250 psi | 63% | 3028 fps | 95% |
| ADI AR 2225 | <<locked>> | 80% | 31,328 psi | 47% | 2707 fps | 97.7% |
| Alliant Reloder-19 | <<locked>> | 80% | 50,604 psi | 76% | 3084 fps | 99.9% |
| Alliant Reloder-22 | <<locked>> | 80% | 46,775 psi | 70% | 3038 fps | 99.6% |
| Alliant Reloder-23 | <<locked>> | 80% | 45,339 psi | 68% | 2959 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 39,668 psi | 59% | 2904 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 80% | 52,199 psi | 78% | 3146 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 88% | 43,642 psi | 65% | 3018 fps | 95.5% |
| Alliant Reloder-50 | <<locked>> | 94% | 47,007 psi | 70% | 3077 fps | 96.1% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 44,048 psi | 66% | 2936 fps | 96% |
| Bofors RP15 | <<locked>> | 80% | 43,395 psi | 65% | 2966 fps | 99.1% |
| Bofors RP30 | <<locked>> | 80% | 36,854 psi | 55% | 2828 fps | 96.9% |
| Bofors RP5 | <<locked>> | 80% | 46,775 psi | 70% | 3038 fps | 99.6% |
| Hodgdon H1000 | <<locked>> | 80% | 37,246 psi | 56% | 2831 fps | 97.7% |
| Hodgdon H4831 | <<locked>> | 80% | 48,486 psi | 73% | 3031 fps | 98.8% |
| Hodgdon H4831 SC | <<locked>> | 80% | 47,659 psi | 71% | 3015 fps | 98.7% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 54,621 psi | 82% | 3058 fps | 100% |
| Hodgdon Retumbo | 81.1 gr | 80% | 38,638 psi | 58% | 2953 fps | 99% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,355 psi | 43% | 1867 fps | 100% |
| IMR 4350 | <<locked>> | 80% | 56,376 psi | 85% | 3130 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 49,168 psi | 74% | 3018 fps | 99% |
| IMR 7828 SSC | <<locked>> | 80% | 44,744 psi | 67% | 3015 fps | 98.7% |
| IMR 7977 Enduron | <<locked>> | 90% | 54,679 psi | 82% | 3081 fps | 95.4% |
| IMR 8133 Enduron | <<locked>> | 84% | 33,373 psi | 50% | 2749 fps | 95.2% |
| Lovex S071 | <<locked>> | 80% | 39,726 psi | 60% | 2808 fps | 99.8% |
| Norma 217 | <<locked>> | 80% | 29,109 psi | 44% | 2641 fps | 95.5% |
| Norma MRP | <<locked>> | 80% | 49,995 psi | 75% | 3114 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 45,353 psi | 68% | 3031 fps | 99.1% |
| Ramshot Magnum | <<locked>> | 80% | 40,843 psi | 61% | 2890 fps | 99.3% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,066 psi | 44% | 1909 fps | 100% |
| ReloadSwiss RS 76 | 86.8 gr | 80% | 38,203 psi | 57% | 2927 fps | 99.6% |
| ReloadSwiss RS 80 | <<locked>> | 82% | 37,927 psi | 57% | 2874 fps | 95.7% |
| Rottweil R 904 | <<locked>> | 80% | 51,358 psi | 77% | 3064 fps | 99.6% |
| Rottweil R 905 | <<locked>> | 80% | 50,270 psi | 75% | 3074 fps | 99.9% |
| SNPE Vectan SP 13 | <<locked>> | 98% | 47,398 psi | 71% | 3022 fps | 95.8% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 49,937 psi | 75% | 3068 fps | 99.9% |
| Somchem S361 | <<locked>> | 80% | 52,518 psi | 79% | 3051 fps | 99.4% |
| Somchem S385 | <<locked>> | 80% | 50,575 psi | 76% | 3041 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 44,295 psi | 66% | 2910 fps | 99.6% |
| Vihtavuori N170 | <<locked>> | 88% | 49,980 psi | 75% | 3041 fps | 95.9% |
| Vihtavuori N555 | <<locked>> | 80% | 50,024 psi | 75% | 3041 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 49,487 psi | 74% | 3114 fps | 99.1% |
| Vihtavuori N565 | <<locked>> | 80% | 41,075 psi | 62% | 2910 fps | 97.5% |
| Vihtavuori N568 | <<locked>> | 82% | 39,088 psi | 59% | 2900 fps | 95.5% |
| Vihtavuori N570 | <<locked>> | 88% | 46,470 psi | 70% | 3104 fps | 96% |
| Winchester StaBALL HD | <<locked>> | 80% | 44,773 psi | 67% | 3028 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 46,746 psi | 70% | 2972 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 60 powders for 7.21 Firebird loaded with the .284 | 145gr | CutEdge LZR MAX. Hodgdon Retumbo delivers the highest muzzle velocity at 3,369 fps; across all powders the maximum-charge window runs from 2,080 fps to 3,369 fps. Accurate 8700 gives the best case fill at 100 %, and 60 of the 60 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 145.0 gr projectile in 0.284" calls for a 1:8.5 twist; slower twists will usually not stabilise this weight. Accurate 8700, Alliant Reloder-50, Hodgdon TrailBoss 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. Hodgdon Retumbo, ADI AR 2218, ReloadSwiss RS 76 rank at the top here: for 7.21 Firebird with the .284 | 145gr | CutEdge LZR MAX they combine a high case fill with complete burn and sit in the upper velocity band. As outliers, Hodgdon 50BMG, Hodgdon US 869, Ramshot LRT 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.