I happen to have a friend that makes his own 'shine.
Every time I see him, I get a bottle of heads and tails from him, it's mostly rubbing alcohol, but I'm sure there's some ethyl and methyl in there for good measure. (It's also good for starting the grill!!)
I just add a little naptha/mineral spirits/kerosene to it, and let my guns soak in it for a few hours first with the grips off.
I used to have access to an ultrasonic cleaner, and that worked well with 1 gallon HOT water, 1 gallon heads and tails, and 2 quarts of murphy's oil soap.
In 3-4 hours, I could detail clean my entire collection!!!
Before you wreck all of your guns, make sure they have the grips and anything wood or plastic removed before dipping in highly active solvents.
Using the active solvents and the ultrasonic cleaner, they must fan dry for 15 minutes then make sure they get re-lubed/re-greased prior to reassembly.
The hot activated solvents+ ultrasonic cleaner strip every bit of dirt, grease, oil, etc off.
I only leave each batch in there 15 minutes, any longer, and I worry about it stripping off the finish.
I suspect that my method is more environmentally friendly than using can after can of brake cleaner/wd-40 to do detail cleans.
Fortunately, I only detail clean guns once a year, late in the fall.