Breakfree CLP ... That is all that I have ever used / needed. It works great and is safe.
https://www.safariland.com/products/holsters-and-gear/gun-cleaning-kits-and-components/cleaners-and-solvents/gun-lubricants-and-protectants/clp-cleaner-lubricant-and-protectant-15337.html
Don't use WD-40.
From Arsenal....
Arsenal, Inc.
3395 S. Jones Blvd #331
Las Vegas, NV 89146 USA
Tel.: 702-643-2220 Fax: 702-643-8860
www.arsenalinc.com
OTHER INFORMATION
WARNING: Modern gun cleaning solvents can be very aggressive. Before use, test solvents on a small portion of each part to check for possible damage to the finish of all the various metal and plastic parts. Keep in mind that more then one type of finish may exist on metal parts. Any damages caused by such aggressive solvents will not be covered under warranty.
IMPORTANT INFORMATION: The paint finish on your rifle is identical to the finish applied on military rifles. Arsenal, Inc. highly recommends using cleaning products approved by the military for such finishes. Your rifle has been effectively tested with a Mil Specification product Break-Free® CLP (Clean, Lubricate, Protect). This product is known to be harmless to your rifle's finish while being an effective cleaner and lubricant. Break-Free® CLP is available commercially and is the only product tested and recommended for use by Arsenal, Inc. Any damages caused by other solvents will not be covered under standard warranty.