I know for a fact that when Glock ships a new pistol, their rails are lubed with copper-based anti-sieze.

I have a big bottle of nickel-based anti-sieze that is for stainless steel fasteners. I use that. Stainless steel and aluminum can gall, and that looks like galling Galling - Wikipedia

if it slides, grease it. if it rotates, oil it. (generally speaking)