School me on loctite for guns

[Desk Jockey]

I have used loctite - blue 242 - for a while. I have had two pistol optic base plates shoot loose In the last few months. In addition to remounting those, I need to mount some scopes.

some guys at the range said I should use red loctite on the optics plates On the rails and blue on the pistol optics and scope rings Some said red all the way around On the rifle scopes.

I am degreasing with acetone and some gun scrubber using picks, paper towels and qtips.

so what say ye?

 

[journeyman713]

Is it stainless?
I don't believe, Loctite 242 works on stainless without an accelerator.

 

[journeyman713]

The same goes for Red

 

[Desk Jockey]

Is it stainless?
I don't believe, Loctite 242 works on stainless without an accelerator.

hmmm. The problem pistols are both stainless - a Ruger 22 and a sig p320 (nitride coated but not likely in the screw holes). Not sure if the mounting screws are stainless or not. What should I be using for blue loctite type performance?

 

[eddielasvegas]

Timely topic OP so thanks.

I'm watching this thread as I have a mount and scope for my 500 Mag to put on so this should help me keep it all buttoned up tight.


Eddie

 

[journeyman713]

Loctite 243 is the upgraded version of 242.
One of tit best features is - it works on stainless steel without adding other products.

 

[Flyrodr]

Here's the "how to":

Threadlocking solutions

Threadlockers lock and seal your threaded assemblies, protecting against vibration, corrosion, and galling. But depending on your need, you have to choose the right threadlocker and consider strength, form, and removability. Which one will you need? LOCTITE® makes your choice easy.

www.henkel-adhesives.com

And here's the "which one":

How to choose the right threadlocking solution?

Don't let a little fastener become a big problem. Learn more about our LOCTITE® threadlockers in our product guide.

www.henkel-adhesives.com

MAYBE red on a base, but I'd suggest blue on rings. Actually, blue on everything. If you do use red and need to remove those screws, putting the tip of a soldering iron on the screw head will usually loosen it without the risk of stripping the head. Or try one of those "micro torches" powered by butane. They have a very tight, focused flame that can be applied to only the screw head. A gunsmith friend suggested the micro torch, and said to apply it for just a few seconds, and there'd be a tiny whiff of smoke, indicating the Loctite had loosened its grip.

 

[eddielasvegas]

Here's some info that may help readers of this thread. After reading this thread earlier today, I reached out to the company that sold me my mount for my S&W 500 Mag and here are the links they sent, along with the information that Loctite and SS will work, as long as the instructions in the last link are followed carefully.

Eddie


LINK 1

LINK 2

LINK 3

 

[journeyman713]

Never use Red on a small screw!

If you want to use your 242 - then add Loctite SF 7649 primer/accelerator for stainless steel applications.
Since you need to buy something, I'd just get the 243.

Also, consider replacing the small screws, reason being - stresses introduced from repeated assembly, and you likely over tightened them.

Another tip,
When torqueing those screws, keep in mind there is a difference between dry torque, and wet torque. A wet (lubricated) screw goes in with approximately 30% less force, meaning it is over stressed if using the dry torque numbers.

Using Loctite is a lubrication, if you don't see a wet torque spec, stay on the lighter side of the torque spec so you don't over tighten and risk breaking the screws.

 

[MuleyFever]

Never use Red on a small screw!

If you want to use your 242 - then add Loctite SF 7649 primer/accelerator for stainless steel applications.
Since you need to buy something, I'd just get the 243.

Also, consider replacing the small screws, reason being - stresses introduced from repeated assembly, and you likely over tightened them.

Another tip,
When torqueing those screws, keep in mind there is a difference between dry torque, and wet torque. A wet (lubricated) screw goes in with approximately 30% less force, meaning it is over stressed if using the dry torque numbers.

Using Loctite is a lubrication, if you don't see a wet torque spec, stay on the lighter side of the torque spec so you don't over tighten and risk breaking the screws.

Can you point to where it says to use 242 with a primer?

From their website, "
Loctite Threadlocker Blue 242 is particularly suited for applications on less active substrates such as stainless steel and plated surfaces, where disassembly is required for servicing."

 

[Buzby]

I would never use red on a firearm. Or anything else for that matter. I use the purple (low strength) on quite a bit of applications.

We’ve had a loctite rep come to the shop I work in (pharmaceutical industry). We use 416 stainless almost exclusively, and he never mentioned it making a difference with any of their products. All loctite does is fill in the voids in the thread interface. The different colors just set up harder. Clean the material thoroughly (their primer works well), use the correct torque, and even the purple should hold well.

 

[journeyman713]

Can you point to where it says to use 242 with a primer?

From their website, "
Loctite Threadlocker Blue 242 is particularly suited for applications on less active substrates such as stainless steel and plated surfaces, where disassembly is required for servicing."

Background, I work in industrial manufacturing, we had the Loctite rep in a few times. I just recall the thing about Loctite needing certain ions to react with, not found in some metals, such as stainless steel. Primer/accelerator adds those needed ions, for the process to work.
The 243 is the 'new and improved' version of 242, and fixed that ion issue.

Loctite's info can be convoluted, but here's a couple references that came up -

 

[Mpw20]

I’d stay away from red in any firearms application. Blue will do fine. Give it time to cure.