I used to be the type that cleaned religiously every singe time I went to the range. After much, much reading I've been trying the “lazy man's” approach. If I'm working on load data I'll run a mop down the bore between loads. And the only reason I do that is to give each load the same starting point as far as a clear bore goes. At the end of the session all I do is use standard cleaners to get the grime out of the bore and finish with a quality oil. I don't cut the copper until the groups begin to fall off. I've done this for this entire summer and my groups have actually gotten smaller to be honest!!