A few decades ago (I still find it hard to think how long I've been doing this stuff sometimes) I was issued an old model Colt Trooper .357 magnum. Those were the ones with the Python frame and skinny 4" barrel. It was butt ugly nasty everywhere. Not feeling confident (in those days) to take it apart and put it back together I came up with a different way of cleaning it. Not sure now why I did it that way but it worked great.
I got a pan the gun would bit in, removed the grips, put the gun in the pan, put water in it and added dishwashing liquid. I put it on the stove top and boiled it. I boiled it till the oily crud stopped coming out of the frame and floating to the surface. The boiling water and dish detergent got it done.
I took it off the stove, poured the boiling water down the sink and took the gun out to lay on a towel on the table. The gun was dry before I got the oil out and put plenty on it and did some dry firing before using my oily rag to wipe off the excess. No issues with normal cleaning after that.
Oh, got an ultrasonic cleaner for Christmas a few years ago. Someday I may use it. And, I don't think I'd put a plastic framed pistol in the boiling water. I have used carb cleaner and brake cleaner on those a few times. Gotta be careful with the carb cleaner. It's pretty harsh on the grips of a Ruger Mk1. I know.
