i used WD-40 over 40 years ago to clean guns. never had any problem with using it. just the reason i don't use it anymore is that there are just much better products than WD-40 available. hell, i don't even use for a penetrating oil anymore. PB Blaster wis much better at breaking loose rusty and crusty bolts. that's what i use at work. in my little gun shop i use Kano Kroil for just about everything. much better product than WD-40.