Thread: Brass damage ?? Help

I fail to see how to tight a headspace can cause massive overpreassure and primer failure?
I dont size my brass till it is difficult to close the bolt IE negative headspace it is a head pressfit and only have pressure problems when I push too hard or when Hornady change batch of Superformance powder....Had to drop a full grain to get back to safe....they have large batch variation and I would say that is likely the fault here.