Originally Posted by beta678
Apply liberal amounts of quality lube.
That is all.
Only apply as much lube as you need to coat the surfaces (bolt carrier group and buffer tube, for the most part). Otherwise, you wind up with a gun full of gunk that cannot perform. Aside from the lube itself gunking everything up, lube holds onto dirt, so you'll have dirty gunk, gunking your gunky internals that work best when not gunked.
You only need a couple of drops of silicone oil in the propane adapter every few fills as well. You don't need to create a pool of oil in the propane tank head. :P