Scope Mount Screw Loose On the Polymer Rail of Smith Wesson MP 15 22

[easycity]

I have a recent model of Smith Wesson M&P 15 22. It has a polymer rail, and factory-installed MBUS front and rear sights.
My problems is that when I tried to mount a 4x scope or a light-weight reflex sight on the polymer rail, the scope ring screws or the mounting screw of the reflex sight always get loose by half a turn, no matter how I tighten them.
I thought the reason could be the elastic nature of the polymer. However, the factory-install MBUS sights are fine on the rail. So I assume that the mounting screws need to be vibration-resistant, or with some kind of loctite.
My question is, will loctite solve the problem? If so, is blue loctite enough, or I have to use red loctite?

 

[allen-1]

a .22 doesn't have a heck of a lot of vibration.

Are you sure you're using the proper size mounts?

If you use loctite, DO NOT USE RED red loc-tite.
Red is designed to require heat to remove.

Heat is not good for polymers... Do I need to go any further with this?

 

[chrbla2000]

Blue loctite is your friend. After not using it several times and having to deal with loose mounts at the range I finally learned to use it every damn time, yes, even on .22's.

 

[easycity]

Thanks for the advice.
It seems no easy to manufacture tight screws. Instead of buying expensive scope rings and scopes, I may need to use loctite with wallet-friendly equipment.
After I am sure about using that reflex scope on the 15 22, I will use blue loctite on the mounting screws.

 

[whacko]

Blue locktite is a gun owners friend.

 

[amm5061]

Strange, I don't have this problem with mine. My red dot and magnifier stay securely attached. I did remove the MBUS sights on mine, and I can tell you they definitely loctited them.

I would say try a drop of blue loctite.

 

[mac1911]

Purple 222 loctite is more gun friendly.

Just a small warning I have had loctite ruin some plastics. In pellet guns

 

[Caveman]

I use blue loctite on all my firearm mounting screws now. From scope mounts, action screws and side saddle shell carriers. Nothing like running a shotgun course having to finger tighten the side saddle action screws after every few shells.

I have heard of loctite not playing nice with some plastics as the poster above stated. So maybe test on another section first?

 

[rocket500]

I put blue loctite on all scope mounting screws. Never had one come loose.

 

[chris_1001]

Blue locktite on every screw. It IS your friend.

Especially on grip screws.