Load Specifications
Bullet Manufacturer:Peregrine
Bullet Weight:150 gr
Bullet Diameter:0.284"
Bullet Length:<<locked>>
Caliber:7.21 Firebird load data
Case Length (l3):2.8"
Cartridge Length (C.O.L.):<<locked>>
Case Capacity:121 Grains of Water
Primer Size:Large Rifle Magnum (LRM)
Barrel Length:26"
Max. allowed Pressure:66,717 psi
Recommended Twist Rate:1:9.0
Load data in caliber 7.21 Firebird with .284 | 150gr | Peregrine VLR-4 bullet and 106 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.
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>> | 86% | 58,291 psi | 87% | 3094 fps | 100% |
| Accurate 3100 | <<locked>> | 86% | 58,726 psi | 88% | 3100 fps | 100% |
| Accurate 8700ᴾ | <<locked>> | 100% | 50,430 psi | 76% | 3064 fps | 97.4% |
| Accurate 8700ᴾ | <<locked>> | 100% | 51,111 psi | 77% | 3074 fps | 97.6% |
| Accurate High Country | <<locked>> | 82% | 57,232 psi | 86% | 3219 fps | 100% |
| Accurate MAGPRO | <<locked>> | 84% | 57,783 psi | 87% | 3219 fps | 99.8% |
| Accurate MAGPRO | <<locked>> | 84% | 58,421 psi | 88% | 3228 fps | 99.9% |
| ADI AR 2209 | <<locked>> | 84% | 59,466 psi | 89% | 3196 fps | 100% |
| ADI AR 2209 | <<locked>> | 84% | 59,959 psi | 90% | 3199 fps | 100% |
| ADI AR 2213 | <<locked>> | 86% | 58,407 psi | 88% | 3215 fps | 100% |
| ADI AR 2213 | <<locked>> | 86% | 59,059 psi | 89% | 3225 fps | 100% |
| ADI AR 2217 | <<locked>> | 94% | 57,972 psi | 87% | 3196 fps | 100% |
| ADI AR 2217 | <<locked>> | 94% | 58,610 psi | 88% | 3202 fps | 100% |
| ADI AR 2218 | <<locked>> | 98% | 59,045 psi | 89% | 3340 fps | 99.5% |
| ADI AR 2218 | <<locked>> | 98% | 59,799 psi | 90% | 3350 fps | 99.6% |
| ADI AR 2225 | <<locked>> | 96% | 57,667 psi | 86% | 3215 fps | 100% |
| ADI AR 2225 | <<locked>> | 96% | 58,291 psi | 87% | 3225 fps | 100% |
| Alliant Power Pro Varmint | <<locked>> | 84% | 60,118 psi | 90% | 3199 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 84% | 59,045 psi | 89% | 3182 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 84% | 59,466 psi | 89% | 3189 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 86% | 58,769 psi | 88% | 3205 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 86% | 59,422 psi | 89% | 3212 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 86% | 56,956 psi | 85% | 3100 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 86% | 57,421 psi | 86% | 3107 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 90% | 57,914 psi | 87% | 3182 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 90% | 58,595 psi | 88% | 3192 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 82% | 57,827 psi | 87% | 3189 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 82% | 58,523 psi | 88% | 3199 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 94% | 56,536 psi | 85% | 3232 fps | 98.9% |
| Alliant Reloder-33 | <<locked>> | 94% | 57,276 psi | 86% | 3241 fps | 99% |
| Alliant Reloder-50 | <<locked>> | 98% | 56,594 psi | 85% | 3219 fps | 98.6% |
| Alliant Reloder-50 | <<locked>> | 98% | 57,363 psi | 86% | 3232 fps | 98.7% |
| Baschieri & Pellagri 109 | <<locked>> | 88% | 58,653 psi | 88% | 3173 fps | 99.3% |
| Baschieri & Pellagri 109 | <<locked>> | 88% | 59,146 psi | 89% | 3179 fps | 99.3% |
| Bofors RP15 | <<locked>> | 88% | 58,131 psi | 87% | 3196 fps | 100% |
| Bofors RP15 | <<locked>> | 88% | 58,784 psi | 88% | 3202 fps | 100% |
| Bofors RP30 | <<locked>> | 92% | 57,682 psi | 86% | 3205 fps | 100% |
| Bofors RP30 | <<locked>> | 92% | 58,305 psi | 87% | 3215 fps | 100% |
| Bofors RP5 | <<locked>> | 86% | 58,769 psi | 88% | 3205 fps | 100% |
| Bofors RP5 | <<locked>> | 86% | 59,422 psi | 89% | 3212 fps | 100% |
| Hodgdon H1000 | <<locked>> | 92% | 59,466 psi | 89% | 3212 fps | 100% |
| Hodgdon H1000 | <<locked>> | 92% | 60,133 psi | 90% | 3222 fps | 100% |
| Hodgdon H4831 | <<locked>> | 84% | 56,855 psi | 85% | 3136 fps | 99.9% |
| Hodgdon H4831 | <<locked>> | 84% | 57,479 psi | 86% | 3150 fps | 99.9% |
| Hodgdon H4831 SC | <<locked>> | 86% | 59,814 psi | 90% | 3186 fps | 100% |
| Hodgdon H4831 SC | <<locked>> | 84% | 56,347 psi | 84% | 3130 fps | 99.8% |
| Hodgdon Hybrid 100V | <<locked>> | 82% | 59,538 psi | 89% | 3084 fps | 100% |
| Hodgdon Hybrid 100V | <<locked>> | 82% | 59,843 psi | 90% | 3084 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 90% | 57,740 psi | 87% | 3284 fps | 100% |
| Hodgdon Retumbo | <<locked>> | 90% | 58,450 psi | 88% | 3291 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,840 psi | 57% | 2051 fps | 100% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 37,869 psi | 57% | 2054 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 84% | 56,985 psi | 85% | 3114 fps | 99.9% |
| IMR 4955 Enduron | <<locked>> | 84% | 57,363 psi | 86% | 3123 fps | 99.9% |
| IMR 7828 SSC | <<locked>> | 86% | 56,840 psi | 85% | 3196 fps | 100% |
| IMR 7828 SSC | <<locked>> | 86% | 57,508 psi | 86% | 3205 fps | 100% |
| IMR 7977 Enduron | <<locked>> | 92% | 59,495 psi | 89% | 3127 fps | 96.8% |
| IMR 7977 Enduron | <<locked>> | 92% | 60,002 psi | 90% | 3136 fps | 97% |
| IMR 8133 Enduronᴾ | <<locked>> | 100% | 60,350 psi | 90% | 3258 fps | 100% |
| IMR 8133 Enduron | <<locked>> | 98% | 56,855 psi | 85% | 3205 fps | 100% |
| Lovex S071 | <<locked>> | 92% | 60,278 psi | 90% | 3123 fps | 100% |
| Lovex S071 | <<locked>> | 90% | 57,000 psi | 85% | 3074 fps | 100% |
| Norma 217 | <<locked>> | 98% | 57,696 psi | 86% | 3215 fps | 100% |
| Norma 217 | <<locked>> | 98% | 58,581 psi | 88% | 3228 fps | 100% |
| Norma MRP | <<locked>> | 84% | 59,030 psi | 88% | 3219 fps | 100% |
| Norma MRP | <<locked>> | 84% | 59,712 psi | 90% | 3225 fps | 100% |
| Ramshot Grand | <<locked>> | 86% | 58,610 psi | 88% | 3222 fps | 100% |
| Ramshot Grand | <<locked>> | 86% | 59,335 psi | 89% | 3232 fps | 100% |
| Ramshot Magnum | <<locked>> | 88% | 56,971 psi | 85% | 3140 fps | 100% |
| Ramshot Magnum | <<locked>> | 88% | 57,595 psi | 86% | 3146 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,899 psi | 58% | 2096 fps | 100% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 38,928 psi | 58% | 2100 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 90% | 58,827 psi | 88% | 3264 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 90% | 59,524 psi | 89% | 3271 fps | 100% |
| ReloadSwiss RS 80 | <<locked>> | 92% | 57,841 psi | 87% | 3235 fps | 99.9% |
| ReloadSwiss RS 80 | <<locked>> | 92% | 58,450 psi | 88% | 3245 fps | 99.9% |
| Rottweil R 904 | <<locked>> | 84% | 59,698 psi | 89% | 3163 fps | 100% |
| Rottweil R 904 | <<locked>> | 84% | 60,118 psi | 90% | 3166 fps | 100% |
| Rottweil R 905 | <<locked>> | 84% | 58,784 psi | 88% | 3173 fps | 100% |
| Rottweil R 905 | <<locked>> | 84% | 59,248 psi | 89% | 3179 fps | 100% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 52,344 psi | 78% | 3077 fps | 97.4% |
| SNPE Vectan SP 13ᴾ | <<locked>> | 100% | 52,823 psi | 79% | 3084 fps | 97.6% |
| SNPE Vectan Tubal 8000 | <<locked>> | 84% | 58,421 psi | 88% | 3169 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 84% | 58,871 psi | 88% | 3176 fps | 100% |
| Somchem S361 | <<locked>> | 82% | 57,174 psi | 86% | 3087 fps | 99.9% |
| Somchem S361 | <<locked>> | 82% | 57,725 psi | 87% | 3097 fps | 99.9% |
| Somchem S385 | <<locked>> | 84% | 59,016 psi | 88% | 3136 fps | 100% |
| Somchem S385 | <<locked>> | 84% | 59,451 psi | 89% | 3143 fps | 100% |
| Vihtavuori N165 | <<locked>> | 88% | 59,292 psi | 89% | 3123 fps | 100% |
| Vihtavuori N165 | <<locked>> | 88% | 59,683 psi | 89% | 3130 fps | 100% |
| Vihtavuori N170 | <<locked>> | 92% | 58,653 psi | 88% | 3159 fps | 98.1% |
| Vihtavuori N170 | <<locked>> | 92% | 59,379 psi | 89% | 3169 fps | 98.2% |
| Vihtavuori N555 | <<locked>> | 84% | 58,450 psi | 88% | 3127 fps | 100% |
| Vihtavuori N555 | <<locked>> | 84% | 58,943 psi | 88% | 3136 fps | 100% |
| Vihtavuori N560 | <<locked>> | 84% | 58,334 psi | 87% | 3228 fps | 100% |
| Vihtavuori N560 | <<locked>> | 84% | 58,972 psi | 88% | 3238 fps | 100% |
| Vihtavuori N565 | <<locked>> | 90% | 59,814 psi | 90% | 3222 fps | 100% |
| Vihtavuori N565 | <<locked>> | 88% | 56,376 psi | 85% | 3166 fps | 99.9% |
| Vihtavuori N568 | <<locked>> | 92% | 57,957 psi | 87% | 3235 fps | 99.7% |
| Vihtavuori N568 | <<locked>> | 92% | 58,740 psi | 88% | 3248 fps | 99.8% |
| Vihtavuori N570 | <<locked>> | 94% | 59,640 psi | 89% | 3310 fps | 99.1% |
| Vihtavuori N570 | <<locked>> | 92% | 56,217 psi | 84% | 3251 fps | 98.6% |
| Winchester StaBALL HD | <<locked>> | 86% | 58,276 psi | 87% | 3196 fps | 100% |
| Winchester StaBALL HD | <<locked>> | 86% | 59,016 psi | 88% | 3205 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 86% | 58,987 psi | 88% | 3136 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 86% | 59,611 psi | 89% | 3143 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% | 47,326 psi | 71% | 2920 fps | 100% |
| Accurate 3100 | <<locked>> | 80% | 47,790 psi | 72% | 2927 fps | 100% |
| Accurate 8700 | <<locked>> | 96% | 43,236 psi | 65% | 2920 fps | 95.3% |
| Accurate 8700 | <<locked>> | 96% | 43,874 psi | 66% | 2936 fps | 95.6% |
| Accurate High Country | <<locked>> | 80% | 53,330 psi | 80% | 3150 fps | 99.9% |
| Accurate MAGPRO | <<locked>> | 80% | 49,951 psi | 75% | 3081 fps | 99% |
| Accurate MAGPRO | <<locked>> | 80% | 50,401 psi | 76% | 3087 fps | 99.1% |
| ADI AR 2209 | <<locked>> | 80% | 51,909 psi | 78% | 3071 fps | 100% |
| ADI AR 2209 | <<locked>> | 80% | 52,388 psi | 79% | 3081 fps | 100% |
| ADI AR 2213 | <<locked>> | 80% | 47,166 psi | 71% | 3018 fps | 99.3% |
| ADI AR 2213 | <<locked>> | 80% | 47,645 psi | 71% | 3025 fps | 99.3% |
| ADI AR 2217 | <<locked>> | 80% | 35,027 psi | 53% | 2736 fps | 96.6% |
| ADI AR 2217 | <<locked>> | 80% | 35,302 psi | 53% | 2746 fps | 96.8% |
| ADI AR 2218 | 97.3 gr | 90% | 43,381 psi | 65% | 3018 fps | 95.9% |
| ADI AR 2218 | 97.3 gr | 90% | 43,845 psi | 66% | 3028 fps | 96.2% |
| ADI AR 2225 | <<locked>> | 80% | 32,271 psi | 48% | 2703 fps | 98.4% |
| ADI AR 2225 | <<locked>> | 80% | 32,634 psi | 49% | 2710 fps | 98.6% |
| Alliant Power Pro Varmint | <<locked>> | 80% | 52,533 psi | 79% | 3074 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 80% | 51,576 psi | 77% | 3058 fps | 100% |
| Alliant Reloder-19 | <<locked>> | 80% | 52,040 psi | 78% | 3068 fps | 100% |
| Alliant Reloder-22 | <<locked>> | 80% | 47,819 psi | 72% | 3018 fps | 99.8% |
| Alliant Reloder-22 | <<locked>> | 80% | 48,283 psi | 72% | 3025 fps | 99.9% |
| Alliant Reloder-23 | <<locked>> | 80% | 46,514 psi | 70% | 2936 fps | 100% |
| Alliant Reloder-23 | <<locked>> | 80% | 47,021 psi | 70% | 2943 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 40,698 psi | 61% | 2884 fps | 100% |
| Alliant Reloder-25 | <<locked>> | 80% | 41,176 psi | 62% | 2894 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 80% | 53,708 psi | 81% | 3127 fps | 100% |
| Alliant Reloder-26 | <<locked>> | 80% | 54,201 psi | 81% | 3133 fps | 100% |
| Alliant Reloder-33 | <<locked>> | 86% | 41,539 psi | 62% | 2933 fps | 95.2% |
| Alliant Reloder-33 | <<locked>> | 86% | 42,076 psi | 63% | 2943 fps | 95.4% |
| Alliant Reloder-50 | <<locked>> | 92% | 44,962 psi | 67% | 2999 fps | 95.8% |
| Alliant Reloder-50 | <<locked>> | 92% | 45,498 psi | 68% | 3005 fps | 96% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 44,904 psi | 67% | 2920 fps | 96.7% |
| Baschieri & Pellagri 109 | <<locked>> | 80% | 45,252 psi | 68% | 2927 fps | 96.8% |
| Bofors RP15 | <<locked>> | 80% | 44,498 psi | 67% | 2946 fps | 99.4% |
| Bofors RP15 | <<locked>> | 80% | 44,802 psi | 67% | 2953 fps | 99.5% |
| Bofors RP30 | <<locked>> | 80% | 37,797 psi | 57% | 2815 fps | 97.5% |
| Bofors RP30 | <<locked>> | 80% | 38,247 psi | 57% | 2825 fps | 97.7% |
| Bofors RP5 | <<locked>> | 80% | 47,819 psi | 72% | 3018 fps | 99.8% |
| Bofors RP5 | <<locked>> | 80% | 48,283 psi | 72% | 3025 fps | 99.9% |
| Hodgdon H1000 | <<locked>> | 80% | 38,174 psi | 57% | 2822 fps | 98.3% |
| Hodgdon H1000 | <<locked>> | 80% | 38,580 psi | 58% | 2828 fps | 98.4% |
| Hodgdon H4831 | <<locked>> | 80% | 49,472 psi | 74% | 3012 fps | 99.2% |
| Hodgdon H4831 | <<locked>> | 80% | 49,893 psi | 75% | 3018 fps | 99.3% |
| Hodgdon H4831 SC | <<locked>> | 80% | 48,631 psi | 73% | 2995 fps | 99.1% |
| Hodgdon H4831 SC | <<locked>> | 80% | 49,066 psi | 74% | 3002 fps | 99.2% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 55,651 psi | 83% | 3028 fps | 100% |
| Hodgdon Hybrid 100V | <<locked>> | 80% | 56,188 psi | 84% | 3038 fps | 100% |
| Hodgdon Retumbo | 81.7 gr | 80% | 39,842 psi | 60% | 2946 fps | 99.5% |
| Hodgdon Retumbo | 81.7 gr | 80% | 40,321 psi | 60% | 2953 fps | 99.5% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,355 psi | 43% | 1837 fps | 100% |
| Hodgdon TrailBoss | <<locked>> | 80% | 28,471 psi | 43% | 1841 fps | 100% |
| IMR 4955 Enduron | <<locked>> | 80% | 50,053 psi | 75% | 2995 fps | 99.3% |
| IMR 4955 Enduron | <<locked>> | 80% | 50,473 psi | 76% | 3002 fps | 99.4% |
| IMR 7828 SSC | <<locked>> | 80% | 45,977 psi | 69% | 3002 fps | 99.1% |
| IMR 7828 SSC | <<locked>> | 80% | 46,456 psi | 70% | 3009 fps | 99.2% |
| IMR 7977 Enduron | <<locked>> | 88% | 52,127 psi | 78% | 2999 fps | 95.1% |
| IMR 7977 Enduron | <<locked>> | 88% | 52,634 psi | 79% | 3009 fps | 95.3% |
| IMR 8133 Enduron | <<locked>> | 84% | 34,345 psi | 51% | 2740 fps | 96.1% |
| IMR 8133 Enduron | <<locked>> | 82% | 32,285 psi | 48% | 2680 fps | 95.1% |
| Lovex S071 | <<locked>> | 80% | 40,727 psi | 61% | 2792 fps | 99.9% |
| Lovex S071 | <<locked>> | 80% | 41,046 psi | 62% | 2799 fps | 100% |
| Norma 217 | <<locked>> | 80% | 30,023 psi | 45% | 2635 fps | 96.4% |
| Norma 217 | <<locked>> | 80% | 30,443 psi | 46% | 2641 fps | 96.6% |
| Norma MRP | <<locked>> | 80% | 51,140 psi | 77% | 3091 fps | 100% |
| Norma MRP | <<locked>> | 80% | 51,793 psi | 78% | 3100 fps | 100% |
| Ramshot Grand | <<locked>> | 80% | 46,543 psi | 70% | 3015 fps | 99.4% |
| Ramshot Grand | <<locked>> | 80% | 47,050 psi | 71% | 3025 fps | 99.5% |
| Ramshot Magnum | <<locked>> | 80% | 41,901 psi | 63% | 2874 fps | 99.6% |
| Ramshot Magnum | <<locked>> | 80% | 42,337 psi | 63% | 2884 fps | 99.7% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,225 psi | 44% | 1883 fps | 100% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 29,211 psi | 44% | 1883 fps | 100% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 39,465 psi | 59% | 2917 fps | 99.9% |
| ReloadSwiss RS 76 | <<locked>> | 80% | 39,914 psi | 60% | 2923 fps | 99.9% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 36,187 psi | 54% | 2795 fps | 95.4% |
| ReloadSwiss RS 80 | <<locked>> | 80% | 36,564 psi | 55% | 2802 fps | 95.5% |
| Rottweil R 904 | <<locked>> | 80% | 52,286 psi | 78% | 3041 fps | 99.8% |
| Rottweil R 904 | <<locked>> | 80% | 52,721 psi | 79% | 3048 fps | 99.8% |
| Rottweil R 905 | <<locked>> | 80% | 51,314 psi | 77% | 3048 fps | 100% |
| Rottweil R 905 | <<locked>> | 80% | 51,808 psi | 78% | 3058 fps | 100% |
| SNPE Vectan SP 13 | <<locked>> | 96% | 45,266 psi | 68% | 2940 fps | 95.5% |
| SNPE Vectan SP 13 | <<locked>> | 96% | 45,919 psi | 69% | 2953 fps | 95.8% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 50,966 psi | 76% | 3048 fps | 100% |
| SNPE Vectan Tubal 8000 | <<locked>> | 80% | 51,459 psi | 77% | 3054 fps | 100% |
| Somchem S361 | <<locked>> | 80% | 53,490 psi | 80% | 3028 fps | 99.6% |
| Somchem S361 | <<locked>> | 80% | 53,867 psi | 81% | 3035 fps | 99.7% |
| Somchem S385 | <<locked>> | 80% | 51,576 psi | 77% | 3018 fps | 100% |
| Somchem S385 | <<locked>> | 80% | 52,025 psi | 78% | 3025 fps | 100% |
| Vihtavuori N165 | <<locked>> | 80% | 45,194 psi | 68% | 2890 fps | 99.8% |
| Vihtavuori N165 | <<locked>> | 80% | 45,629 psi | 68% | 2897 fps | 99.8% |
| Vihtavuori N170 | <<locked>> | 86% | 47,674 psi | 71% | 2959 fps | 95.6% |
| Vihtavuori N170 | <<locked>> | 86% | 48,153 psi | 72% | 2969 fps | 95.8% |
| Vihtavuori N555 | <<locked>> | 80% | 51,256 psi | 77% | 3018 fps | 100% |
| Vihtavuori N555 | <<locked>> | 80% | 51,590 psi | 77% | 3025 fps | 100% |
| Vihtavuori N560 | <<locked>> | 80% | 50,604 psi | 76% | 3094 fps | 99.4% |
| Vihtavuori N560 | <<locked>> | 80% | 51,242 psi | 77% | 3104 fps | 99.5% |
| Vihtavuori N565 | <<locked>> | 80% | 42,061 psi | 63% | 2894 fps | 98.1% |
| Vihtavuori N565 | <<locked>> | 80% | 42,482 psi | 64% | 2904 fps | 98.2% |
| Vihtavuori N568 | <<locked>> | 80% | 37,260 psi | 56% | 2815 fps | 95.2% |
| Vihtavuori N568 | <<locked>> | 80% | 37,666 psi | 56% | 2825 fps | 95.4% |
| Vihtavuori N570 | 91.1 gr | 86% | 44,367 psi | 67% | 3015 fps | 95.7% |
| Vihtavuori N570 | 91.1 gr | 86% | 44,933 psi | 67% | 3028 fps | 95.9% |
| Winchester StaBALL HD | <<locked>> | 80% | 46,296 psi | 69% | 3012 fps | 100% |
| Winchester StaBALL HD | <<locked>> | 80% | 46,891 psi | 70% | 3018 fps | 100% |
| Winchester Supreme 780 | <<locked>> | 80% | 47,906 psi | 72% | 2953 fps | 99.8% |
| Winchester Supreme 780 | <<locked>> | 80% | 48,312 psi | 72% | 2959 fps | 99.9% |
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 106 powders for 7.21 Firebird loaded with the .284 | 150gr | Peregrine VLR-4. ADI AR 2218 delivers the highest muzzle velocity at 3,350 fps; across all powders the maximum-charge window runs from 2,051 fps to 3,350 fps. Accurate 8700 gives the best case fill at 100 %, and 106 of the 106 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 150.0 gr projectile in 0.284" calls for a 1:9.0 twist; slower twists will usually not stabilise this weight. Accurate 8700, Accurate 8700, 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. ADI AR 2218, Hodgdon Retumbo, Vihtavuori N570 rank at the top here: for 7.21 Firebird with the .284 | 150gr | Peregrine VLR-4 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.