Load Specifications
Load data in caliber 7.21 Firebird with .284 | 145gr | SUS-TAC HPT bullet and 52 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 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% | 58,015 psi | 87% | 3130 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 49,879 psi | 75% | 3087 fps | 96.9% |
| Accurate MAGPRO | <<locked>> | 84% | 57,232 psi | 86% | 3248 fps | 99.6% |
| ADI AR 2209 | <<locked>> | 84% | 58,958 psi | 88% | 3228 fps | 100% |
| ADI AR 2213 | <<locked>> | 86% | 57,856 psi | 87% | 3248 fps | 100% |
| ADI AR 2217 | <<locked>> | 94% | 57,188 psi | 86% | 3225 fps | 100% |
| ADI AR 2218 | <<locked>> | 98% | 58,262 psi | 87% | 3363 fps | 99.2% |
| ADI AR 2225 | <<locked>> | 96% | 56,855 psi | 85% | 3248 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 84% | 58,392 psi | 88% | 3212 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 86% | 58,378 psi | 88% | 3238 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 88% | 60,263 psi | 90% | 3189 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 90% | 57,435 psi | 86% | 3219 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 82% | 57,421 psi | 86% | 3228 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 94% | 55,927 psi | 84% | 3258 fps | 98.6% |
| Alliant Reloder-50 | <<locked>> | 98% | 56,260 psi | 84% | 3251 fps | 98.3% |
| Baschieri & Pellagri 109 | <<locked>> | 88% | 57,972 psi | 87% | 3199 fps | 99% |
| Bofors RP15 | <<locked>> | 88% | 57,754 psi | 87% | 3228 fps | 100% |
| Bofors RP30 | <<locked>> | 92% | 57,145 psi | 86% | 3238 fps | 100% |
| Bofors RP5 | <<locked>> | 86% | 58,378 psi | 88% | 3238 fps | 100% |
| Hodgdon H1000 | <<locked>> | 92% | 58,871 psi | 88% | 3245 fps | 100% |
| Hodgdon H4831 | <<locked>> | 86% | 60,336 psi | 90% | 3232 fps | 99.9% |
| Hodgdon H4831 SC | <<locked>> | 86% | 59,335 psi | 89% | 3215 fps | 99.9% |
| Hodgdon Hybrid 100V | <<locked>> | 82% | 59,146 psi | 89% | 3120 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 90% | 56,797 psi | 85% | 3314 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,971 psi | 57% | 2080 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 86% | 60,321 psi | 90% | 3205 fps | 100% |
| IMR 7828 SSC | <<locked>> | 88% | 60,350 psi | 90% | 3294 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 92% | 58,900 psi | 88% | 3150 fps | 96.3% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 59,683 psi | 89% | 3291 fps | 100% |
| Lovex S071 | <<locked>> | 92% | 59,959 psi | 90% | 3159 fps | 100% |
| Norma 217 | <<locked>> | 98% | 57,290 psi | 86% | 3251 fps | 100% |
| Norma MRP | <<locked>> | 84% | 58,639 psi | 88% | 3251 fps | 100% |
| Ramshot Grand | <<locked>> | 86% | 57,827 psi | 87% | 3251 fps | 100% |
| Ramshot Magnum | <<locked>> | 88% | 56,376 psi | 85% | 3173 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,914 psi | 58% | 2126 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 90% | 58,015 psi | 87% | 3297 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 92% | 57,261 psi | 86% | 3264 fps | 99.8% |
| Rottweil R 904 | <<locked>> | 84% | 59,030 psi | 88% | 3189 fps | 100% |
| Rottweil R 905 | <<locked>> | 84% | 58,378 psi | 88% | 3205 fps | 100% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 51,793 psi | 78% | 3104 fps | 97% |
| SNPE Vectan Tubal 8000 | <<locked>> | 84% | 57,986 psi | 87% | 3202 fps | 100% |
| Somchem S361 | <<locked>> | 82% | 56,884 psi | 85% | 3120 fps | 99.8% |
| Somchem S385 | <<locked>> | 84% | 58,740 psi | 88% | 3173 fps | 100% |
| Vihtavuori N165 | <<locked>> | 88% | 58,726 psi | 88% | 3153 fps | 100% |
| Vihtavuori N170 | <<locked>> | 92% | 58,465 psi | 88% | 3189 fps | 97.7% |
| Vihtavuori N555 | <<locked>> | 84% | 58,247 psi | 87% | 3169 fps | 100% |
| Vihtavuori N560 | <<locked>> | 84% | 57,885 psi | 87% | 3261 fps | 99.9% |
| Vihtavuori N565 | <<locked>> | 90% | 59,335 psi | 89% | 3255 fps | 100% |
| Vihtavuori N568 | <<locked>> | 92% | 57,537 psi | 86% | 3268 fps | 99.6% |
| Vihtavuori N570 | <<locked>> | 94% | 58,914 psi | 88% | 3337 fps | 98.7% |
| Winchester StaBALL HD | <<locked>> | 86% | 57,508 psi | 86% | 3232 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 86% | 58,595 psi | 88% | 3166 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% | 47,384 psi | 71% | 2959 fps | 100% |
| Accurate 8700 | <<locked>> | 98% | 46,253 psi | 69% | 3018 fps | 95.9% |
| Accurate MAGPRO | <<locked>> | 80% | 49,705 psi | 75% | 3114 fps | 98.7% |
| ADI AR 2209 | <<locked>> | 80% | 51,532 psi | 77% | 3104 fps | 99.9% |
| ADI AR 2213 | <<locked>> | 80% | 46,818 psi | 70% | 3048 fps | 99% |
| ADI AR 2217 | <<locked>> | 80% | 34,969 psi | 52% | 2769 fps | 96.2% |
| ADI AR 2218 | 96 gr | 90% | 43,033 psi | 65% | 3045 fps | 95.3% |
| ADI AR 2225 | <<locked>> | 80% | 32,329 psi | 48% | 2736 fps | 98.1% |
| Alliant Reloder-19 | <<locked>> | 80% | 51,256 psi | 77% | 3094 fps | 99.9% |
| Alliant Reloder-22 | <<locked>> | 80% | 47,587 psi | 71% | 3051 fps | 99.7% |
| Alliant Reloder-23 | <<locked>> | 80% | 46,325 psi | 69% | 2972 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 40,509 psi | 61% | 2920 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 80% | 53,214 psi | 80% | 3163 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 88% | 44,599 psi | 67% | 3038 fps | 95.9% |
| Alliant Reloder-50 | <<locked>> | 92% | 44,875 psi | 67% | 3028 fps | 95.3% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 44,614 psi | 67% | 2946 fps | 96.2% |
| Bofors RP15 | <<locked>> | 80% | 44,353 psi | 66% | 2982 fps | 99.2% |
| Bofors RP30 | <<locked>> | 80% | 37,782 psi | 57% | 2851 fps | 97.2% |
| Bofors RP5 | <<locked>> | 80% | 47,587 psi | 71% | 3051 fps | 99.7% |
| Hodgdon H1000 | <<locked>> | 80% | 38,043 psi | 57% | 2851 fps | 97.9% |
| Hodgdon H4831 | <<locked>> | 80% | 49,182 psi | 74% | 3041 fps | 98.9% |
| Hodgdon H4831 SC | <<locked>> | 80% | 48,327 psi | 72% | 3025 fps | 98.8% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 55,317 psi | 83% | 3064 fps | 100% |
| Hodgdon Retumbo | 80.6 gr | 80% | 39,595 psi | 59% | 2979 fps | 99.2% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,471 psi | 43% | 1864 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 49,748 psi | 75% | 3028 fps | 99.1% |
| IMR 7828 SSC | <<locked>> | 80% | 45,629 psi | 68% | 3028 fps | 98.8% |
| IMR 7977 Enduron | <<locked>> | 90% | 55,332 psi | 83% | 3091 fps | 95.5% |
| IMR 8133 Enduron | <<locked>> | 84% | 34,360 psi | 52% | 2776 fps | 95.7% |
| Lovex S071 | <<locked>> | 80% | 40,901 psi | 61% | 2831 fps | 99.9% |
| Norma 217 | <<locked>> | 80% | 30,139 psi | 45% | 2671 fps | 96.1% |
| Norma MRP | <<locked>> | 80% | 50,836 psi | 76% | 3127 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 46,209 psi | 69% | 3045 fps | 99.2% |
| Ramshot Magnum | <<locked>> | 80% | 41,756 psi | 63% | 2910 fps | 99.5% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,211 psi | 44% | 1909 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 39,160 psi | 59% | 2946 fps | 99.7% |
| ReloadSwiss RS 80 | <<locked>> | 82% | 39,015 psi | 58% | 2900 fps | 96.1% |
| Rottweil R 904 | <<locked>> | 80% | 51,953 psi | 78% | 3071 fps | 99.6% |
| Rottweil R 905 | <<locked>> | 80% | 51,053 psi | 77% | 3084 fps | 99.9% |
| SNPE Vectan SP 13 | <<locked>> | 96% | 45,034 psi | 68% | 2969 fps | 95% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 50,705 psi | 76% | 3081 fps | 99.9% |
| Somchem S361 | <<locked>> | 80% | 53,243 psi | 80% | 3061 fps | 99.5% |
| Somchem S385 | <<locked>> | 80% | 51,401 psi | 77% | 3051 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 45,049 psi | 68% | 2923 fps | 99.7% |
| Vihtavuori N170 | <<locked>> | 86% | 47,616 psi | 71% | 2992 fps | 95.2% |
| Vihtavuori N555 | <<locked>> | 80% | 51,169 psi | 77% | 3058 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 50,270 psi | 75% | 3127 fps | 99.2% |
| Vihtavuori N565 | <<locked>> | 80% | 42,076 psi | 63% | 2930 fps | 97.8% |
| Vihtavuori N568 | <<locked>> | 82% | 39,943 psi | 60% | 2917 fps | 95.9% |
| Vihtavuori N570 | 89.9 gr | 86% | 44,121 psi | 66% | 3048 fps | 95.2% |
| Winchester StaBALL HD | <<locked>> | 80% | 45,774 psi | 69% | 3045 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 47,674 psi | 71% | 2986 fps | 99.7% |
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 | 145gr | SUS-TAC HPT. ADI AR 2218 delivers the highest muzzle velocity at 3,363 fps; across all powders the maximum-charge window runs from 2,080 fps to 3,363 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 145.0 gr projectile in 0.284" calls for a 1:8.5 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. Hodgdon Retumbo, ADI AR 2218, Vihtavuori N570 rank at the top here: for 7.21 Firebird with the .284 | 145gr | SUS-TAC HPT 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.