My son bought a new Sig AR 15 yesterday. I have never owned one or been around one much. Anything we need to know about them? What do you use to clean them with such as what kind of cleaning rod? What type and how much oil or lube do you need on them? I have never used the rail system for mounting things on, do the screws need loc-tite or just a good tightening. This whole thing is new to me help bring me up to date.