I avoid using Simple Green on aluminum as I find that even at low concentrations it etches the aluminum.That is what I use for cleaning gun parts. Works great. It doesn’t completely remove the fouling from the surfaces but what it leaves is usually easily wiped away.
One caution of water based degreasers, it seems most of them are not safe for aluminum. The ones commonly mentioned, Simple Green, Zep Purple etc will all attack aluminum.
Even the purple simple green which is often said is safe for aluminum online, seems to cause a white powdery surface afterwards. They make an aircraft specific simple green that is branded as aluminum safe but I have not tried that one.