As long as you don't live in a really moist environment, or the bore isn't wet, you won't harm it by not doing any cleaning after a range session.
If it makes you feel better, you can run a slightly moist patch through, or even a dry one. If do you use any oil, be sure to run a dry patch through after.
But I live in a dry environment and I don't do anything at all to the bore after a range session.
One other note, sometimes changing bullets (ie brands) will change how the bore fouls. Your best accuracy will probably be after you've shot one bullet type 5-20 rounds.
Last edited by Zak Smith; 08-21-2010 at 21:56..