Sorry for the bacon grease silliness.
The first time I clean a new gun, I field strip it, clean it well, and then coat all the metal parts with Miltec-1 oil. I put all the parts (no polymer!) on an old cookie sheet. Depending on the time of year, I'll either put the cookie sheet on top of my woodstove for a few minutes, or in a VERY slow oven for a few.
Some guys use a blow dryer, fire the weapon until well warmed, or set the parts in the sun.
I then wipe it all back down. The Miltec-1 penetrates the pores of the metal and some stays on the metal parts.
I put a small amount of Miltec-1 grease on the rail surfaces and reassemble the gun.
It works for me. All of my guns have been flawless in operation, and NONE show signs of rust.
Be careful whatever grease you use on the rail surfaces, as too much can attract lint and dust and have the opposite effect you had hoped.
Click on
http://www.militec-1.com/ then firearms, then
FIREARMS APPLICATION INSTRUCTIONS
Printable version - PDF
I bought their large bottle of oil, but the little tub of grease they sent me with my "free sample" will probably last my lifetime.
I don't see where the general public is invited to ask for a free sample any more, but they do have a link for LE and military.
--Plex