Ask my cousin how that works.You are so right so many people never tear their bolt apart and clean it.MAY JUST BE THE PROBLEM. Old oil, bolt grease even powder blow back. Best of luck.
Right before a late season elk hunt, I told him to clean out his bolt. He didn't. His 7RM on the last evening with a bull in sight went "clunk". I grabbed my rifle, and he dumped the bull with it.
Got home, and he cleaned the bolt body insdoe with degreaser. It was black running out.