Good gun oil won't congeal. WD-40 will, over time. Don't use WD-40 on moving parts.

Put a few drops of oil on a patch and put a light coat of oil in the bore and chamber if the gun is to be stored for an extended time.
Chamber should be fairly dry and not oil soaked if you plan to shoot again soon.
A light coat of oil in the barrel is O.K. as it will get removed when you shoot.

Not a good idea to lube firing pin channels and the inside of mag bodies.
If you are going to use anything in those two areas, use dry lube like Rem Dri or Hornady One Shot. Wet oil will pick up crud and lint and you don't want crud to accumulate there.

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U. S. Army Veteran