Hiss served 3 1/2 years for perjury. Several who invoked their fith amendment rights were held "in contempt of Congress" and served up to 1 year in prison.
Having ACP reading material could mean arrest for subversion and plotting to overthrow the goverment.
Being called a Communist would get you deported if you were a foreign citizen.
Yes, there were arrests made and prison time served.
The left media needs to exaggerate the period for the image of "Reds under the bed" right-wingers. Gotta keep the us against them ...