I have a Pre War M70 Winchester and a Mauser 98 in .243 Win. I field strip the bolt, lube with Powdered Graphite. Clean the bore with Hoppe's #9 on a bronze brush. When I lube the outside of the bolt, I use Tri-Flow spray oil. Slicker than snot. The use of WD40 to clean a bore, does not remove copper or lead deposits. They will build up to the point, the bore will become inaccurate.
When using Hoppe's #9 and the bronze brush, cycle the cleaning rod 12 times. Then run dry patches through the bore until the patches come out clean. Do not be disturbed if the patches come out green. The bronze brush and Hoppe3s make Copper Sulfate and that is green.
My method of cleaning a High power Rifle is taught by the US Army Marksmanship Unit at Camp Perry.
Doug