You'll find lots of opinions. Frank White at Compass Lake Engineering wants you to use Neco Molyslide on his AR trigger. It is a two-stage trigger, so you have the take-up portion of the trigger to press through, and lubrication keeps that stage smooth.
I am a little leery of using brake cleaner or any other degreaser and not following up with a lubricating material that will offer some corrosion resistance. I've left 1911 trigger groups unlubricated for extended periods (7 or 8 thousand rounds) and not had a problem. This was shooting lead bullets, and some of the lube seems to vaporize and blow around and condense all over the gun, and that may help?
The last couple of years I've been experimenting with two permanent lubricants. One is Moly-Fusion
, which puts a micro-thin lubricating metal conversion layer on parts. This is completely dry and very durable (you can put it in a barrel and it withstands firing and keeps fouling down) and offers some added corrosion resistance. The other is Plate+ Silver
which is based on an older NASA technology, but which also withstands firing in a barrel for quite a number of rounds. Though Moly-Fusion should have it beat on peak temperature tolerance, it seems to work as advertised. Plate+ Silver is a colloidal suspension of acid-neutralized sub-micron size molybdenum disulfide particles in a petroleum-based lubricant that bonds electrostatically to iron.
To use either lube, you would start by cleaning the trigger group parts. Mineral spirits works fine to final clean before treating with Moly-Fusion. The Moly-Fusion is applied in a mix with mineral oil or mineral spirits. You warm the object to be treated and, keeping it warm, rub the treating mix in for 20 minutes or so (I use a Q-tip for trigger and sear engagement surfaces). Then you can clean the parts off with mineral spirits and wipe them dry.
For Plate+ Silver, you would first clean the parts. Mineral spirits works, again, but there is a Plate+ Green that is the petroleum-based Plate+ component only (no moly) and which can be used to prep the surface like a pre-cleaner. Once you are ready for the Silver version, soak the parts in it for 72 hours at room temperature, then remove them and wipe all visible traces off the surface with dry patches.
In both cases you will have lubrication in place and working. The limitation of Plate+ is it does not work on aluminum, while Moly-Fusion does. Moly-Fusion, for my money, gives a more positively smooth feel to two sliding surfaces, while Plate+ has a slicker feel. Both lubricant's have much lower sliding coefficients of friction than steel on steel; 0.07 is advertised for Moly-Fusion, and 0.02 is advertised for Plate+ Silver. Hardened steel on hardened steel is about 0.78 static and 0.42 sliding, by way of comparison.
I prefer Moly-Fusion on a two-stage trigger and Plate+ Silver on a single-stage trigger. The former seems to clean up hesitation a bit better in the first stage of the trigger, while the latter seems more inclined to allowing a sudden slip, which a crisp trigger should have. I suspect the difference in static and sliding friction coefficients is lower for Moly-Fusion, but would have to test that carefully to be sure my perception isn't just subjective?
Plate+ is simpler and more idiot proof to apply, but also more prone to creeping into places you don't want it or to having excess remain behind on pins and in holes and springs, from where it can splash or creep out onto other things. You just have to make your own choice about that aspect of it, and make your own decision as to which you might prefer to use? I have not tried applying one over the other on purpose, though I have used one on surface A and the other on surface B of two sliding parts, and it worked, but nothing special happened. I suspect Moly-Fusion, since it will work through oil, can probably be successfully applied to something previously treated with Plate+, but the reverse would not go so well other than to fill in any defects in the Moly-Fusion coating. More fuel for experimentation, there. Knock yourself out.