CatShooter
It appears opinions vary, I was taught to lube my lugs and not lube my cases.

(sorry but opinions do vary)
Bolt Maintenance Methods & Materials
Proper Cleaning and Lubrication Ensures Bolt Reliability and Long Life
by Germán A. Salazar, Contributing Editor
http://www.accurateshooter.com/technical-articles/bolt-maintenance-methods-materials/
BOLT Lubrication
Like any piece of machinery subjected to high pressure and cyclical movement, the bolt needs lubrication. There are three main areas on a typical bolt that need lube: the locking lugs, the cocking cam, and the extraction cam.
1. The Rear Surface of the Locking Lugs
There are two lugs on most bolts, three or four lugs on some actions. Wipe these clean with a paper towel before re-applying the lube. Dab a little of the grease on the tip of the small screwdriver and spread it on the lugs. This should be a thin, even coat. Just thick enough to cover the metal but not globbed on. This picture shows the lugs wiped clean before lubing. A locking lug recess cleaning tool such as Sinclair Int’l offers is useful to ensure that any grit and bits of brass that collect in the receiver’s lug recesses get cleaned out.
Benchrest Central
Thread: Very Best Bolt Lug Grease
http://benchrest.com/showthread.php?84175-Very-Best-Bolt-Lug-Grease
Greasing and lubricating your M1 Garand
http://www.garandgear.com/m1-garand-grease
And then there is those who say to run your AR15 "wet".
AR Lube Advice From The Experts
http://www.rifleshootermag.com/rifles/ar-15/ar-lube-advice-from-the-experts/
CatShooter......never say never.
And in my opinion and especially anyone who neck sizes only should keep their locking lugs greased.