Load Specifications
Load data in caliber .221 Rem. Fireball with .233 | 55gr | MRR Green Hunting bullet and 12 powders. The key underlying parameters are shown in the table above. The recommended powders for this cartridge and bullet combination are ReloadSwiss RS 36, Lovex S053 and IMR 4227.
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: 24"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate No. 11 FS | <<locked>> | 82% | 40,596 psi | 87% | 2638 fps | 98.6% |
| ADI AR 2205 | <<locked>> | 84% | 40,872 psi | 88% | 2566 fps | 99.6% |
| ADI AR 2207ᴾ | <<locked>> | 100% | 39,624 psi | 85% | 2740 fps | 98.5% |
| Hodgdon TrailBossᴾ | <<locked>> | 100% | 27,818 psi | 60% | 1696 fps | 100% |
| IMR 4227 | <<locked>> | 92% | 41,582 psi | 90% | 2664 fps | 97.5% |
| Lovex S053 | <<locked>> | 94% | 41,829 psi | 90% | 2680 fps | 99.7% |
| ReloadSwiss RS 14ᴾ | <<locked>> | 100% | 27,093 psi | 58% | 1732 fps | 100% |
| ReloadSwiss RS 36 | <<locked>> | 94% | 41,930 psi | 90% | 2717 fps | 97.5% |
| Shooters World SOCOM | <<locked>> | 84% | 40,089 psi | 86% | 2615 fps | 96.2% |
| SNPE Vectan BA6 1/2 | <<locked>> | 96% | 40,872 psi | 88% | 2543 fps | 100% |
| Vihtavuori N110 | <<locked>> | 88% | 41,176 psi | 89% | 2618 fps | 100% |
| Vihtavuori N120ᴾ | <<locked>> | 100% | 40,074 psi | 86% | 2707 fps | 99.3% |
Recommended = one of the top powders for this cartridge and bullet combination.
Start Load - Barrel Length: 24"
| Powder | Charge | FR | MaxP | % | V(0) | z |
|---|---|---|---|---|---|---|
| Accurate No. 11 FS | <<locked>> | 80% | 38,218 psi | 82% | 2595 fps | 98.2% |
| ADI AR 2205 | <<locked>> | 80% | 36,260 psi | 78% | 2477 fps | 99.1% |
| ADI AR 2207 | <<locked>> | 90% | 29,341 psi | 63% | 2500 fps | 95.4% |
| Hodgdon TrailBoss | <<locked>> | 80% | 20,088 psi | 43% | 1512 fps | 100% |
| IMR 4227 | 12.6 gr | 86% | 34,606 psi | 75% | 2520 fps | 95.6% |
| Lovex S053 | 11.5 gr | 80% | 27,963 psi | 60% | 2375 fps | 96.9% |
| ReloadSwiss RS 14 | <<locked>> | 80% | 19,696 psi | 42% | 1549 fps | 100% |
| ReloadSwiss RS 36 | 13.7 gr | 88% | 35,070 psi | 76% | 2579 fps | 95.7% |
| Shooters World SOCOM | <<locked>> | 82% | 37,724 psi | 81% | 2569 fps | 95.5% |
| SNPE Vectan BA6 1/2 | <<locked>> | 80% | 26,513 psi | 57% | 2257 fps | 100% |
| Vihtavuori N110 | <<locked>> | 80% | 33,156 psi | 71% | 2470 fps | 100% |
| Vihtavuori N120 | <<locked>> | 86% | 26,498 psi | 57% | 2385 fps | 95.4% |
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 12 powders for .221 Rem. Fireball loaded with the .233 | 55gr | MRR Green Hunting. ADI AR 2207 delivers the highest muzzle velocity at 2,740 fps; across all powders the maximum-charge window runs from 1,696 fps to 2,740 fps. ADI AR 2207 gives the best case fill at 100 %, and 12 of the 12 powders fall inside the usable 80–100 % fill window.
Relative to the caliber's maximum pressure (320 MPa), the top charges use 58–90 %, leaving at least 10 % headroom. The 55.0 gr projectile in 0.223" calls for a 1:9.0 twist; slower twists will usually not stabilise this weight. ADI AR 2207, 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. ReloadSwiss RS 36, Lovex S053, IMR 4227 rank at the top here: for .221 Rem. Fireball with the .233 | 55gr | MRR Green Hunting 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.