K8MAGUR300: 24" .300 OSSM Upper Receiver

Upper conversion unit for your complete AR-15 lower receiver designed for the Olympic Super Short Magnum.

Fully assembled headspaced and test-fired. Includes one 5-round magazine. The ejection port cover is not included because the port is enlarged to allow the OSSM cartridge to fit through it.

The 300 OSSM cartridge is a SAAMI approved cartridge developed by Olympic Arms in conjunction with Hunting Shack Munitions and Hogdon Powder based on the .243 WSSM cartridge necked out to 30 caliber. The 300 Olympic Super Short Magnum will deliver a 25 slug at 3,040 fps! That's true .30-06 ballistics from a standard unmodified .223/5.56 AR15 lower. 

Ammunition manufactured by HSM® is available through Olympic Arms.