Heck I can't see what it would hurt. The only thing I'd advise against is acetone for guns if they had plastic parts and oven cleaner as I have seen people use them on engines and it eats the paint off. Paint thinner, vinegar, arm and hammer washing powders, lemon juice, about anything around the house could be used as a degreaser. I've never used engine degreaser on a gun but it works great on gas or diesel and doesn't effect plastic or paint so it should be fine. I'd test a small spot under the hand guard and check an hour later no matter what I used though. I do that with any new chemicals I'm not certain of.