We have the concept of parole now. Technically parolees are still serving their sentence, and have agreed to forfeit some of their rights until their sentence is up. At that point, they should have all of their rights back in my opinion.
We might have some disagreement there regarding gun ownership for violent felons. But nothing that couldn't be resolved in sentencing. Aggravated assault by a 20 year old in a bar fight is different than murder from the perspective of recidivism. It's a minor part of the discussion.