+ 1 + --- All good advice - BUT - none of this is concrete. Sometimes you could get just one sign, ( depending on primers, barrel, throat, amb. temp. etc,,) . Like they said above, get a mic., some good books with no distractions. Have had extractor marks with no other clues. My experience shows that the first shot through a clean barrel "IS NO INDICATOR" of what is to follow. Usually have less speed and fewer pressure signs. gook luck