I like Outers gunslick for shotgun hinge pins and semi auto handgun rails. A little goes a long way and it stays on. Comes in a tube, it looks like black graphite in a heavy oil, or light grease.
Been using Gunslick on certain gun parts, for the past 45 years or more. Dad got me an Outers cleaning kit that long ago and a wee tube came with the kit.
Got another tube of it some years ago, to indicate how long the original one lasted and how sparingly it had been applied. Worked really well on the trigger/sear in the Bushmaster.
Currently have about 6 or 8 different lubes in the cupboard, for various uses. Including Kroil and some "home made" ATF applications. Rust inhibitors are an important component of most ATFs, due to the steel parts in auto trannies.
Some folks' learnin' curves just look like circles...3A Camp/also hunt 4B