The .300 Blackout is based off of a shortened 5.56x45mm case that is necked to .30 caliber. For AR-15 platform rifles and pistols it only requires changing the barrel to go from 5.56 to .300 Blackout. The Blackout's main purpose is to be used at subsonic velocities in suppressed firearms. Many bolt action and single shot rifles are now being produced in this caliber as well.
* Starline Brass does not sell any loaded ammunition. What you are purchasing are brass cases only and will need to be loaded into ammunition in order to be fired from a firearm.
I have bought Starline pistol brass for years and have been very pleased. When they started making rifle brass I couldn't wait. The 300 AAC BO brass is wonderful! They are consistent in overall length, neck diameter, weight and primer tightness. I couldn't ask for more.
Joseph Leighty Scottdale, Pennsylvania
December 09, 2017
I'm never disappointed in Starline brass and I am so glad they finally got into rifle brass. I recently bought the 300 AAC Blackout brass and began to work with it. Without exception it could be loaded right out of the bag. I have found no deformed case mouths yet and the length is remarkably good. I have to do something to the cases or I don't feel I prepared them so I have been reaming the inside of the flashholes to make sure they are uniform and I chamfered the case mouths though I don't think the outside is in need of that operation. Primer seating feels very uniform and tight enough. These are great cases and I plan to buy more when the time comes. Thanks Starline for another great product.