CLR doesn't contain petroleum. What it does contain are various acids (citric and lactic, I believe) used to break down stains (lime, rust, etc.). If you're screws are oxidizing, it should be OK to soak them. For any other metal parts, I would think you should strip them of all plastic, rubber & silicon parts before soaking.
Soaked parts should be scrubbed to remove any rust (wear glove - the stuff is corrosive), then rinsed in hot water to remove acid residue. Preheat your oven to about 200-250 degF, place metal parts on a cooking sheet, and place in oven for about 3-5 minutes to rapidly dry the parts. Coat with silicon oil and wipe down.
Or, if you know the screw size & pitch, get new screws from the hardware store.
If you're paranoid, test with some scrap plastic or out of sight location on the gun (e.g., inside surface of your stock) before going whole hog.
VFC SCAR-L - VFC SCAR SSR - KJW Hi-Capa 5.1 - CAW M79
The Three Sisters - WE G39 E/K/C
Originally Posted by kalnaren
Stalker stays where he is.
His BB's fly across the country to hit their target.