This ammunition from American Marksman has mixed reviews. Caliber Armory has not tested this ammo and cannot vouch for its quality.
Lake City Brass
Boxer Primers and Projectiles
Note from manufacturer: With the popularity of 300 BLK caliber SBR's / Pistols and the many different barrel lengths associated with these configurations which may affect proper cycling, users should be aware that all testing of this ammo is done on a 10.5" barrel with optimum results. As it is designed for use in rifles, American Marksman will not be responsible for cycling issues resulting from firing from a SBR / Pistol with barrel lengths less than 10.5"