Thanks a lot, guys. In case it's helpful to anyone, I had a good e-mail conversation with the VP of R&D at Simple Green this morning. She recommended Simple Green Pro HD (sold exclusivelty through Home Depot) for gun cleaning. It's the same chemical formulation as their Extreme Aircraft Cleaner, which is specifically formulated to be safe on aircraft grade aluminum.
She forwarded me testimonials from gun owners who have been using Pro HD as a cleaner for years. One professional shooter and instructor said it worked better than Hoppe's and other products he used to use in 1/3rd of the time and at a fraction of the cost. This stuff is cheap at Home Depot, and is typically mixed 1:6 with water, so a 1 gallon jug ends up giving you 6 gallons of solution after mixing. Additionally, she also sent me lab results where they soaked aircraft grade aluminum in a diluted solution for 24 hours. At moderate to higher dilutions (e.g., up to their recommended max of 1:13, where they mix 1 part Pro HD with 13 parts water), the tests show no discoloration or damage to aircraft aluminum after 24 hours. At the highest concentration they recommend which is 1:5, there's minor discoloration on the aluminum after soaking in the solution for 24 hours. Given this, seems like Simple Green Pro HD would be safe for cleaning our PCRs at moderate dilutions (say 1:6 to 1:9), especially since the solution won't remain on the pistol for more than 10-20 minutes before being rinsed off. I'm not crazy about water on my gun, but compressed air should be able to blow it out of the crevices. I guess water is better than a chemical solvent that eats the aluminum though.
So it's one more option to consider. I might try Simple Green Pro HD, followed by a spraying of Barricade rust protectant, and then a light oiling.
