The subject of lubrication is vast, and opinions vary. In most situations, as one of the instructors has been know to joke, “sunscreen would probably work for a while.” Adherents of one or another brand of lubricant will extol its virtues endlessly. Whatever you use, use it. A dry AR is a rifle looking to malfunction. Invariably in the patrol rifle and patrol rifle instructor classes taught in NEMRT, we have rifles whose owners thought they had sufficiently lubed them start to malfunction right after lunch of the first full firing day. You don’t want so much lube on it that it splatters you and bystanders on every shot. But if, when you touch the carrier through the ejection port, you don’t get oil on your fingertip, the carrier (and thus the bolt) is probably too dry. Some have suggested that the best way to keep an AR-15 or M-16 running reliably is to keep it dry, to prevent it from attracting dirt. They are wrong. You need oil to reduce friction, and carry grit and dirt away from the working parts. Running a rifle while it is dry will simply make it malfunction sooner, not later.
Let me repeat that, just in case someone you know is a strenuous advocate of running your gun dry: they are wrong.
So where to lube?
You do not need a 55 gallon drum for a dip-lube, nor do you need a shaving brush to give every surface a nice, even coating of 5W30. But you do need lubricant, and some places matter more than others. By “wet” I mean a visible layer of lubricant on the surface. By “damp” I mean the surface has been clearly oiled, but there is no danger of oil dripping off the part. An automotive example to demonstrate the differences: if you pull the dipstick out of your engine, the part that was in the oil is “dripping.” The rest of the stick is “wet”. If you wipe it with a cloth or paper towel, the dipstick is now “damp.”
Bolt: You want the extractor joints, pivot pin and spring each wet with oil. The locking lugs should be damp, and the bearing band (the slightly raised part behind the cam pin hole) should be wet.
Carrier: The running rails, the raised sections that run the length of the carrier should be wet. The rest of the exterior should be damp. The cam pit slot should be wet, as should the cam pin riding there. The bolt tunnel should be damp.
Trigger mechanism: the bolt, trigger, disconnector and safety should be damp. The pivot pins should be wet.
The rest of the rifle can be damp or dry, as you wish, or as maintenance regulations or climate require. In the course of shooting and cleaning, all the other parts will end up with a very light film of oil. The only way to make them absolutely dry again is with liberal applications of degreasing aerosol. But it isn’t needed. Unless you’re in an extremely humid climate for long periods of time, the exterior steel isn’t going to rust. The plastic and aluminum aren’t going to rust even then.
For more information and details on the care, maintenance and smithing of AR-15s, purchase Gunsmithing the AR-15 from Gun Tests.
