The .300 AAC upper for sale at Gorilla Machining was designed to achieve energies like the Mikhail 7.62x39 Soviet in an AK-47 while using standard AR-15 magazines at their full capacity. The AK-47 7.62x39 Soviet's cartridge taper prevented reliable feeding in AR-15 magazines and created wear on the bolt. From the 14.5" barrel of the AR-15, the 5.56 round has an effective point target range of 500 yards. The bullet has significant drop, drift, and energy loss at that distance.
From a 16" barrel, a 125gr .300 Black Out round has a lower velocity and similar bullet drop and drift at shorter distances.
However, it has the same amount of energy at 700 yards that the 5.56 has at 500 yards. In terms of hit probability, the Blackout has an effective range of 450 yards. From a 9" barrel, the 125 gr BLK round has the same muzzle energy as the 5.56 from a AR-15, and 5 percent more energy at 440 yards. In comparison with AK47 Mikhail 7.62×39mm rounds, 300 BLK rounds with varying loads have a better ballistics and more energy out of similar length barrels.
.300 AAC Blackout (designated as the .300 BLK by the SAAMI and .300 AAC Blackout by the C.I.P, also known as 7.62×35mm) is an intermediate cartridge developed in the United States by Advanced Armament Corporation (AAC) for use in the M4 carbine. Its purpose is to achieve ballistics similar to the AK47 7.62×39mm cartridge, or even more similarly, the 7.92×33mm Kurz cartridge in an M4 while using standard M4 magazines at their normal capacities.