Hot water works yes the British did it that way they also ran a piece of screen down the barrel I've used both I also will plug one end of the barrel and fill it up with easy off oven cleaner then let it sock for 10 or 15 mins it usually takes everything off. Then just do normal cleaning again.WD40 and/or 3in1 oil works good for final cleaning. Also ATF trans fluid.
I got a Russian capture 98k recently. After stripping it to record the Waffenampts and inspection, I started to clean the bore. My brushes and jags are .30cal and my patches are British military surplus flannelette in a roll.
So far I've soaked it with Hoppes No.9 and now get clean oily patches and slightly black dry patches. Switch to RB17 bore solvent, and I'm pulling rusty brown patches off the jag. Scrub with a bronze brush. Run the patches until they come out clean. Switch to Foaming Bore Cleaner. It isn't getting much out, but it floats off anything lingering. Switch to some abrasives - JB Paste and an old yellow bottle of Remington scratchy liquid. The patches go from clean to black. Then the cycle repeats. I think I am progressively working through very old layers of fouling that have been there since WWII.




















































