I've used brake cleaner quite a few times. It's probably the best bang-for-buck option to clean up seriously gunked up dirty guns. I don't have plastic except for a few grips (which I remove), so it doesn't worry me. Afterwards, I do tend to oil things up.
A common practice is to strip down a pistol (at least field strip, maybe further), and after cleaning and degreasing it with brake cleaner or another strong solvent, I let them dry (sometimes using compressed air), drop all the parts in a ziploc bag, shoot a couple sprays of ballistol (the handpump can) or similar in the bag and rub it around, and let it sit on top of my stove awhile. I have an old stove with a big flat cast iron skillet, and the pilot light keeps that area quite warm to the touch.
About an hour sitting there, the oil has spread over the warm metal completely in a thin film. It's usually still a bit oily, so I wipe it off with a soft cloth. Add a little to the slide rails and barrel lugs etc, and reassemble.
I don't do this every time, but whenever I do, the gun is super-clean and runs great.