About once a year or if it my AR gets really dirty (sand, mud). I use Slip2000 to clean it all up, use compressed air to blow out all the cleaner and debris. Quick wipedown with CLP and then wipe off the CLP. There's not much to wear here. The latch and tube have metal to metal contact but that's it, the plastic stock isn't going to wear the tube and doesn't need lube.
You're a lot more likely to get rust on the carbon steel latch than you are wearing out the tube out for lack of lube (which is why I use CLP) especially in a humid area.
Inside, lube the buffer spring with CLP.
Chief Armorer for Elite Shooting Sports in Manassas VA
Chief Armorer for Corp Arms (FFL 07-08/SOT 02)
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