From the Henkel website, the manufacturer of Loctite:
What is red Loctite used for?
Loctite® Threadlocker Red 271™
Product Overview. Loctite Threadlocker Red 271 is designed to lock and seal threaded fasteners permanently and prevent loosening from vibration.

I use it sometimes. For instance to secure a wobbly rear sight on my BSA. It won't move anymore
I have blue Loctite which will secure screws, which can then still be removed with normal tools and without heat. I use it on trigger guard and tap plate screws.
I also have green Loctite, which I use to secure silencer adapters on barrels (for instance on my Titan Manitou).
It is a bit confusing when you look at all the different Loctite numbers though. There are lots and lots of types.