300 AAC Blackout Load Data from Sierra Bullets

Sierra Bullets has just added extensive load data for the 300 AAC Blackout (300 BLK) cartridge. Developed for the AR15 platform, the 300 BLK offers AR shooters a large-caliber option in both subsonic and supersonic variants. The 300 BLK can be made from modified .223 Rem brass or necked-up .221 Fireball cases. We like to form our .300 BLK brass by necking-up the excellent Lapua .221 Fireball brass.

Sierra Cartridge Comments: 300 AAC Blackout
The 300 AAC Blackout (300 BLK, or 7.62x35mm) was created by Advanced Armament Corp. and Remington in order to provide the military with a way to shoot .30 caliber bullets from the M4 platform with only a barrel change. It has since become popular for a wide range of uses including hunting and home defense.

The cartridge shares case-head dimensions and body taper with the .223 Remington. Not only does this allow for compatibility with existing magazines and bolts, but it allows reloaders to form 300 BLK brass from the vast supply of 5.56mm or .223 cases. However, since .223/5.56 cases need to be cut-down and reformed, it can be simpler to neck up .221 Fireball brass.

The 300 AAC Blackout is similar to previous wildcats, such as the .30-221 and .300 Fireball, as well as the proprietary 300 Whisper®. However the 300 BLK was the first SAAMI-approved (and standardized) cartridge of this type. Moreover, any company is free to make firearms or ammunition for the 300 BLK.

300 AAC Blackout is popular with hunters, who may not be allowed to legally hunt with .223 in their state, and who prefer .30-caliber bullets for medium-sized game. It provides similar effectiveness to the 7.62×39mm or the slightly more powerful 30-30 cartridges, while working in the more up-to-date AR15 platform. Effective range for hunting is about 100-150 yards.