You are right, he is a 'moderate libertarian' according to his voting record at OnTheIssues. His American Conservative Union rating is the same as John McCain's (83% lifetime) and his CATO rating is to the left of McCain by a few points.
You can't call him 'Radical' when he hasn't accomplished anything in his decades in office.. Useless moderate libertarian would probably be a better definition.
Then why isn't his Moderate Libertarian butt in the Libertarian party?