WHAT DOES BULK 300 BLACKOUT AMMO MEAN?

If I'm going 300BO, are going to be build for a can and probably ten or 12 inch pistol. Will not invest in just one In case the law doesn't transform or will get one particular down the road when money are available. My quick barreled 308 contains a war comp on it just expecting the regulation to vary.62x39mm cartridge was the typical cartridge for