I always use blue Loctite when mounting a scope. I have never used the red Loctite, it's always been my understanding that the red is for permanent applications. I change my my too much to permanently mount a scope on anything.
As the others have posted, read first and if you don't understand have the dealer assist you. When I was a tool and die maker we used yellow and sometimes the steal would break before the bond. There are also stronger products for permanently bonding strain gages and other items permanently, and I mean permanent!
One thing about the industrial strength: be neat, don't pick your nose or scratch anything you don't want bonded that will have to be removed in an emergency room!
That's what I use for scope installs. Threads (commonly) are #6-48 and will hold rock solid with the blue, no need for red there (or most places really).
One tip, use VERY sparingly, use the tip of a toothpick to apply, you DON'T have to use a whole drop or cover all of the threads, a very little bit goes a LONG way. If you see blue oozing out of the holes when you install, there's too much.
Use the Blue Loctite for scope mounting applications. If you were to use the red, the mount would be permanent, or you'd have one heck of a time trying to get the screws loose. Red is for applications in which you would want a stronger, permanent bond - farm machinery, industrial, etc. Blue Loctite is the same stuff that is packaged by Uncle Mikes and costs half of what Uncle Mikes does. Any major auto supply store should sell Blue Loctite.
I use the loctite 222 which is purple. It is a little harder to find, but the best for your application. Another thing that works good, is cheaper, and easier to find, your wife's discarded fingernail polish.
Good luck, and if you use the blue, have a small torch ready when you go to take a mount off. A little heat on the screw will help loosen the loctite and should keep you from messing up your screws.
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