I highly recommend Mark's gun rights podcast. I listen to every episode - they're very good as well as informative on current gun rights issues.
You can listen directly on his website, or if you have an ipod you can also subscribe to his podcast through itunes & listen whenever. I like to listen to his & other podcasts while I'm going for my daily walk.
Mark also lists several other good podcasts on his website that I listen to as well. Check them out.