Load Specifications
Load data in caliber 7.21 Firebird with .284 | 160gr | Winchester FailSafe bullet and 49 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.
A valid access license is required to use the Personalized Load Calculator.
You can find more information in our FAQ: How can I use the Personalized Load Calculator?
Max Load - Barrel Length: 26"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate 3100 | <<locked>> | 84% | 59,843 psi | 90% | 3028 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 57,087 psi | 86% | 3097 fps | 99.2% |
| Accurate MAGPRO | <<locked>> | 82% | 59,350 psi | 89% | 3156 fps | 100% |
| ADI AR 2213 | <<locked>> | 84% | 59,799 psi | 90% | 3146 fps | 100% |
| ADI AR 2217 | <<locked>> | 92% | 59,799 psi | 90% | 3133 fps | 100% |
| ADI AR 2218 | <<locked>> | 94% | 56,942 psi | 85% | 3219 fps | 99.7% |
| ADI AR 2225 | <<locked>> | 94% | 60,220 psi | 90% | 3156 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 82% | 60,017 psi | 90% | 3107 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 84% | 60,336 psi | 90% | 3136 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 84% | 58,479 psi | 88% | 3028 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 88% | 60,002 psi | 90% | 3117 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 92% | 59,059 psi | 89% | 3189 fps | 99.6% |
| Alliant Reloder-50 | <<locked>> | 96% | 59,756 psi | 90% | 3189 fps | 99.4% |
| Baschieri & Pellagri 109 | <<locked>> | 86% | 59,451 psi | 89% | 3104 fps | 99.7% |
| Bofors RP15 | <<locked>> | 86% | 59,698 psi | 89% | 3127 fps | 100% |
| Bofors RP30 | <<locked>> | 90% | 59,814 psi | 90% | 3146 fps | 100% |
| Bofors RP5 | <<locked>> | 84% | 60,336 psi | 90% | 3136 fps | 100% |
| Hodgdon H1000 | <<locked>> | 88% | 57,043 psi | 86% | 3091 fps | 100% |
| Hodgdon H4831 | <<locked>> | 82% | 57,827 psi | 87% | 3071 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 82% | 56,898 psi | 85% | 3058 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 88% | 60,118 psi | 90% | 3222 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 38,101 psi | 57% | 2001 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 82% | 57,653 psi | 86% | 3045 fps | 100% |
| IMR 7828 SSC | <<locked>> | 84% | 58,450 psi | 88% | 3133 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 90% | 60,234 psi | 90% | 3064 fps | 97.7% |
| IMR 8133 Enduron | <<locked>> | 96% | 58,769 psi | 88% | 3146 fps | 100% |
| Lovex D100 | <<locked>> | 92% | 58,407 psi | 88% | 3061 fps | 96.5% |
| Lovex S071 | <<locked>> | 88% | 58,320 psi | 87% | 3005 fps | 100% |
| Norma 217 | <<locked>> | 94% | 56,826 psi | 85% | 3110 fps | 100% |
| Ramshot Grand | <<locked>> | 84% | 60,278 psi | 90% | 3156 fps | 100% |
| Ramshot Magnum | <<locked>> | 86% | 58,755 psi | 88% | 3077 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 39,233 psi | 59% | 2047 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 86% | 56,782 psi | 85% | 3140 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 90% | 60,220 psi | 90% | 3182 fps | 100% |
| Rottweil R 905 | <<locked>> | 82% | 59,959 psi | 90% | 3104 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 92% | 58,407 psi | 88% | 3061 fps | 96.5% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 58,595 psi | 88% | 3104 fps | 99.1% |
| SNPE Vectan Tubal 8000 | <<locked>> | 82% | 59,625 psi | 89% | 3097 fps | 100% |
| Somchem S385 | <<locked>> | 82% | 60,176 psi | 90% | 3064 fps | 100% |
| Vihtavuori 20N29ᴾ | <<locked>> | 100% | 51,895 psi | 78% | 3009 fps | 96.6% |
| Vihtavuori N165 | <<locked>> | 84% | 56,608 psi | 85% | 2999 fps | 100% |
| Vihtavuori N170 | <<locked>> | 90% | 60,176 psi | 90% | 3104 fps | 98.9% |
| Vihtavuori N555 | <<locked>> | 82% | 60,104 psi | 90% | 3058 fps | 100% |
| Vihtavuori N560 | <<locked>> | 82% | 59,756 psi | 90% | 3159 fps | 100% |
| Vihtavuori N565 | <<locked>> | 86% | 57,638 psi | 86% | 3100 fps | 100% |
| Vihtavuori N568 | <<locked>> | 90% | 60,321 psi | 90% | 3189 fps | 100% |
| Vihtavuori N570 | <<locked>> | 90% | 57,783 psi | 87% | 3192 fps | 99.3% |
| Winchester StaBALL HD | <<locked>> | 82% | 56,521 psi | 85% | 3074 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 84% | 60,133 psi | 90% | 3064 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% | 52,402 psi | 79% | 2920 fps | 100% |
| Accurate 8700 | <<locked>> | 92% | 42,453 psi | 64% | 2828 fps | 95.9% |
| Accurate MAGPRO | <<locked>> | 80% | 55,317 psi | 83% | 3091 fps | 99.9% |
| ADI AR 2213 | <<locked>> | 80% | 52,011 psi | 78% | 3022 fps | 100% |
| ADI AR 2217 | <<locked>> | 80% | 39,160 psi | 59% | 2762 fps | 98.7% |
| ADI AR 2218 | 92.3 gr | 84% | 39,073 psi | 59% | 2838 fps | 95.1% |
| ADI AR 2225 | <<locked>> | 80% | 36,492 psi | 55% | 2736 fps | 99.8% |
| Alliant Reloder-19 | <<locked>> | 80% | 56,188 psi | 84% | 3051 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 52,721 psi | 79% | 3018 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 80% | 51,358 psi | 77% | 2923 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 45,672 psi | 68% | 2894 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 82% | 40,596 psi | 61% | 2831 fps | 95.7% |
| Alliant Reloder-50 | 95.9 gr | 86% | 41,191 psi | 62% | 2831 fps | 95.3% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 48,892 psi | 73% | 2923 fps | 98.3% |
| Bofors RP15 | <<locked>> | 80% | 49,095 psi | 74% | 2953 fps | 100% |
| Bofors RP30 | <<locked>> | 80% | 42,598 psi | 64% | 2844 fps | 99.3% |
| Bofors RP5 | <<locked>> | 80% | 52,721 psi | 79% | 3018 fps | 100% |
| Hodgdon H1000 | <<locked>> | 80% | 42,743 psi | 64% | 2841 fps | 99.6% |
| Hodgdon H4831 | <<locked>> | 80% | 54,027 psi | 81% | 3009 fps | 99.9% |
| Hodgdon H4831 SC | <<locked>> | 80% | 53,142 psi | 80% | 2995 fps | 99.9% |
| Hodgdon Retumbo | <<locked>> | 80% | 44,976 psi | 67% | 2969 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,718 psi | 43% | 1795 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 54,172 psi | 81% | 2986 fps | 99.9% |
| IMR 7828 SSC | <<locked>> | 80% | 50,952 psi | 76% | 3009 fps | 99.9% |
| IMR 7977 Enduron | <<locked>> | 84% | 49,661 psi | 74% | 2884 fps | 95.4% |
| IMR 8133 Enduron | <<locked>> | 80% | 34,084 psi | 51% | 2654 fps | 96.8% |
| Lovex D100 | <<locked>> | 90% | 54,418 psi | 82% | 2992 fps | 95.6% |
| Lovex S071 | <<locked>> | 80% | 45,223 psi | 68% | 2799 fps | 100% |
| Norma 217 | <<locked>> | 80% | 34,722 psi | 52% | 2680 fps | 98.9% |
| Ramshot Grand | <<locked>> | 80% | 52,141 psi | 78% | 3031 fps | 100% |
| Ramshot Magnum | <<locked>> | 80% | 47,094 psi | 71% | 2894 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,515 psi | 44% | 1837 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 45,092 psi | 68% | 2946 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 41,350 psi | 62% | 2841 fps | 98% |
| Rottweil R 905 | <<locked>> | 80% | 56,217 psi | 84% | 3045 fps | 100% |
| Shooters World 50 BMG | <<locked>> | 90% | 54,418 psi | 82% | 2992 fps | 95.6% |
| SNPE Vectan SP 13 | <<locked>> | 90% | 41,437 psi | 62% | 2782 fps | 95.1% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 55,883 psi | 84% | 3041 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 56,347 psi | 84% | 3009 fps | 100% |
| Vihtavuori 20N29 | <<locked>> | 98% | 48,370 psi | 73% | 2943 fps | 95.6% |
| Vihtavuori N165 | <<locked>> | 80% | 49,690 psi | 74% | 2890 fps | 100% |
| Vihtavuori N170 | <<locked>> | 80% | 42,960 psi | 64% | 2789 fps | 95% |
| Vihtavuori N555 | <<locked>> | 80% | 56,405 psi | 85% | 3005 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 55,854 psi | 84% | 3100 fps | 100% |
| Vihtavuori N565 | <<locked>> | 80% | 46,992 psi | 70% | 2917 fps | 99.5% |
| Vihtavuori N568 | <<locked>> | 80% | 42,090 psi | 63% | 2851 fps | 97.7% |
| Vihtavuori N570 | 86.1 gr | 80% | 40,306 psi | 60% | 2841 fps | 95.1% |
| Winchester StaBALL HD | <<locked>> | 80% | 52,533 psi | 79% | 3015 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 52,489 psi | 79% | 2949 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 49 powders for 7.21 Firebird loaded with the .284 | 160gr | Winchester FailSafe. Hodgdon Retumbo delivers the highest muzzle velocity at 3,222 fps; across all powders the maximum-charge window runs from 2,001 fps to 3,222 fps. Accurate 8700 gives the best case fill at 100 %, and 49 of the 49 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 1:11.5 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 | 160gr | Winchester FailSafe 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.