It is an artifact left over from the machining processes...a "chip". If the bore, crown, and rifling are all right, now that you removed it, forget it and try your hardest not to let it ruin your life.
Sometimes you get what you pay for, sometimes you only pay more for what you get.
Three shots are not a "group"...they are a "few".
If the Bible is the literal, infallible, unerring word of God...where are all those witches I am supposed to kill?