This morning I was looking through some once-fired brass that I have and noticed that I had a great range of different primer strike marks on brass fired through my different handguns. Some .45ACP and revolver rounds had large and deep strikes, whereas some of my 9mm and .40 cal brass looked like it was barely nicked at all. Getting the idea from an internet site, I setup a fixture with a dial indicator to measure the depth of the primer strikes. The results ranged from as little as .004"-.005" (on 9mm fired through a Ruger P95DC) to as much as .022 for brass fired through a K-Frame S&W .38 revolver (older type with firing pin on the hammer). I don't recall that I have had a failure-to-fire problem with any of my guns. However, I also don't want a misfire to happen at the worst possible moment. Is there any industry or gunsmithing standard measurement or criteria on what constitutes a light primer strike?