I prefer Breakfree CLP or if a real soak is required kerosene with a shot of Hobbs #9. Once loose Breakfree to lube.
I assume you mean Hopps not Hobbs. If so, I've never heard of using it that way. I have LOTS of it that I don't use anymore. I use bore tech instead. I like it much better.
I'll have to try both as a penetrating oil.