Since I got shangaid into helping at the BP range at Scout camp about 30 years ago and most years since, and having to clean fifteen or twenty rifles and shotguns every PM, I got into the habit of using El-Cheapo-Supremo windshield washer solvent diluted with cold water 50-50. I swabbed the bores with flannel donated by a fabric store. I just swabbed until the bore was clean, then wiped the bore with Ox Yoke Wonder Lube. When we opened the range after ten months of the rifles sitting in an unheated room at the camp I noticed that the bores were all fine.
When the idiot fire marshal, piss be upon him, decided from his ultimate head up his poop chute so far all he can hear is his intestines rumbling that BP was too dangerous and made us go to BP substitute, I quit and haven't been back in years. No clue how the bores are now, but my three are all pretty much like new.
I got tangled up with a re-enactor who shoots a real live pre 1800 .35 cal. Pennsylvania Rifle, and a Real Charleville Musket that was used in the Revolutionary war. He cleans the same way I do except he uses lard. His 200 and somethin' yr old rifle is like new inside as is his Charleville Musket. That ol' windshield washer solvent and grease is magic. The one thing I've learned is to avoid petroleum products like the plague. EXCEPT for Dexron II automatic xmission fluid. It is synthetic whale oil and used by the drop is also magic. If getting windshield washer fluid is inconvenient, I go for house brand window washing spray containing water, isopropol alcohol, ammonia and blue dye. I could use Windex, but I was born cheap and had a relapse. Cleaning a muzzleloading rifle takes about ten minutes, requires no hot water and about four square inches of cheap cotton flannel.
WD-40 is just kerosene and perfume.
My patch material is the thinnest pillow ticking I can find, washed and dried to get rid of the sizing, then ripped into 3/4" to 1" strips, soaked with hot lard and pressed between several layers of newspaper. I keep the patching strips in a zip-lock bag in my shooting box. I've been using the same chunk of ticking I got from the scrap bit at the fabric store for a dollar about 20 or 25 years ago. The flannel came from the same bin. I use the flannel for patching the .285" balls cast in an antykew ball mold I shoot in the .30 barrel I made for my T-C Hawken. Talk about cheap shootin' the load is the 35.6 grain roundball, ten grains of 3F and home made caps.
All y'all's milieage may vary.
Three Hawks