I have been reading David Horiwitz book, Radical Son. His parents were communists and he said that only about 200 Communists lost their jobs and few spent time in jail.
For such "dedicated" people, that wasn't very many for the un-America committee to stop.
You're thinking of the House Committee on Un-American Activities. McCarthy's subcommittee was in the Senate and only investigated security risks in the federal government.
I read Radical Son too. Great read.