Pressure Signs
Physical clues that a load is running too hot, including flattened primers, ejector marks on the case head, and stiff bolt lift on extraction.
Pressure signs are the visible and tactile warnings that chamber pressure has climbed past safe limits for a given load. Common indicators appear on the fired case and during extraction: a primer that is flattened or cratered, a shiny ejector mark pressed into the case head, difficult bolt lift, or a case that sticks in the chamber. Loosened primer pockets that no longer hold a primer snugly are another late sign that a load has been run hard.
These clues are useful but imprecise, because they appear at different pressures across different rifles, brass lots, and primer brands, and some dangerous loads show no obvious sign at all. They are a reason to stop and back off, never a license to keep climbing until they appear. Careful handloaders work up charges slowly and treat the first hint of any pressure sign as the ceiling for that combination.