Hoppe's No. 9 Lubricating Oil

I’m wondering if this will work on firearms, fishing reels, and other precision mechanisms. Also, does it harden or gum?

Word on the street is that it can be used on firearms, fishing reels, and other precision mechanisms. I also heard it does not harden or gum.

It does! And it does not.

Can confirm, it can be used on firearms, fishing reels, and other precision mechanisms. However, in my experience, it does not harden or gum.