Getting frustrated---how often are your dots and mounts coming loose?

[dogcaller]

These posts are why, when I get back into dot guns, it will be with a direct-mill mounted Acro P2.

Yeah, I hear you. It's why my second MRDS is a Steiner MPS, direct-milled onto a G-17. But I really like the Beretta and want to keep using it...

[dogcaller]

Grainger might well have something similar. It's worth a shot.

Found some of those brushes at Harbor Freight. clipped the wire at the end so I could reach in even further and wore out the brush. Also used dental picks, gently, and spent a couple hours on LTT surgery last night. Everything thoroughly cleaned, degreased, new screws (also degreased), painted on the blue Loctite. Will let the slide sit on the mantle until Sunday.

Just realized that I forgot to do a sage smudge before and after--dammit.


Thanks, all, for your help--I really appreciate it.





Edited to add that it still seems like the 10lbs of torque required by the LTT instructions seems a little light, but here we go again...

[LukeNCMX]

Loctite 248 chapstick is the best product for this application.

VC3 is junk mostly because a proper application process is absolutely ridiculous. If someone sold high quality screws at the correct length with pre-applied VC3 99% of the issue with VC3 would be resolved. I imagine it is cost prohibitive because I am pretty sure ND Industries (Makers of Vibra-tite) sell commercial quantities of screws with pre-applied with thread locker.

With all that being said, why put up with VC3?? The only real redeeming quality of VC3 is it is less likely to cause broken screws on removal than loctite. A better solution if you have issues with broken screws on removal is to heat up the screw head with a soldering iron to loosen the loctite before you try to unscrew. You probably won't need to do that if you stop using a factory glock MOS plats, don't reuse the same screws a bunch of times, and stop drowning them in wet loctite.

[EVP]

[*]Apply Loctite 243 or 248 to the bottom 3rd of screw threads


I’ve not shot my LTT yet (waiting on a holster) but I mounted the Holosun 507C optic with McMaster 4-40 screws at 12 in/lbs - I’ve done this a couple times with good results, so we’ll see.

Excellent info as always!

Just a few quick questions if you don’t mind.


Would you mind sharing what specific product or SKU- those McMaster screws you use for the LTT and 507c?

Concerning Loctite:
What do you use to remove and clean old blue 243 loctite?
Have you heard of anyone using green 290? (Maybe a little overkill)


Thanks

[TCinVA]

Edited to add that it still seems like the 10lbs of torque required by the LTT instructions seems a little light, but here we go again...

A dirty little secret of my practices that no one should follow:

I use high quality bits from Chapman because they fit fasteners properly to prevent rounding off engagement surfaces, they are made in America and they hold up to hard use. I tighten the fastener until I feel just the slightest bit of flex in the Chapman bit itself. This is likely a little more torque than is advised.

Like I said, kids...don't be like me.

[DaBigBR]

Loctite 248 chapstick is the best product for this application.

I used to believe that, but found that the stick would dry out and/or become contaminated over time. I think there is also some concern about it getting into the very fine threads.

I have settled on buying larger bottles of 242 or 243. They are easier to shake well (which is important and overlooked), allow more precise application than the small vials you cut or break open, and are easier to adequately re-seal.

[stomridertx]

I used to believe that, but found that the stick would dry out and/or become contaminated over time. I think there is also some concern about it getting into the very fine threads.

I have settled on buying larger bottles of 242 or 243. They are easier to shake well (which is important and overlooked), allow more precise application than the small vials you cut or break open, and are easier to adequately re-seal.

A happy medium is Permatex 24010 Medium Strength Threadlocker Blue Gel. The gel is easy to work with on tiny fasteners. I've had good results with Permatex equivalents to Loctite products, and I like that I can buy Permatex products in Auto parts stores close to me and not have to worry that I'm getting a Chinese counterfeit product on Amazon or eBay (a real concern).

[SoCalDep]

Excellent info as always!

Just a few quick questions if you don’t mind.


Would you mind sharing what specific product or SKU- those McMaster screws you use for the LTT and 507c?

Concerning Loctite:
What do you use to remove and clean old blue 243 loctite?
Have you heard of anyone using green 290? (Maybe a little overkill)


Thanks

For some reason I can’t get the login page to load on McMaster.com, so the best I can do right now is the following:

Alloy steel flat head IP10 Torx drive screws... the dimensions when I measured the included screws were 4-40 x 5/16” for RMR and 4-40 x 1/4” for Holosun. I have found that the 5/16” screws work for Holosun as well and they seat right at the bottom of the plate/T-nut, don’t engage the slide, and so that’s what I used. I always test fit both lengths with the optic and plate and go with what appears to be the best fit.

As far as removing old Loctite, normally I’ll just use a round toothpick with an alcohol swab... getting it into the whole and twisting it around until it’s pretty clean. Un-Cure could be used but I generally don’t find it necessary. I do a lot of optic switching and a lot for others and I haven’t seen any trends of optics coming loose more often after being re-installed or switched.

I wouldn’t use Loctite 290 for optic mounting. It says heat is required for disassembly and Loctite 243 and 248 work fine for my use. The only exception is some of the 2021-2022 era Staccato plates... We would use a (VERY small) dab of red Loctite on the plate-to-slide screws. The optic-to-plate got 248.

[Archer1440]

There was a secondary question about getting the threadlocking compound off. This is another problem with VC3... Rather than simply prevent movement, it almost functions as a gasket... I believe this contributes to why I’ve seen so many optics come loose with VC3... and it cakes on and sticks to everything. I saw a product called “”Un-Cure” from Bob Smith Industries as a possible thread locker remover. I’ve only used it a couple times, but it worked to get rid of the huge amount of VC3 caked on one pistol, including dripping down into the channel for the extractor assembly and hardening (yes - it was done very wrong... VC3 is less forgiving of not following the instructions because it requires air curing while Loctite is anaerobic).

What you also need to know is that VC3 is essentially acrylic plastic dissolved in a carrier of MEK (Methyl Ethyl Ketone). MEK is therefore an excellent solvent for VC3. There are several different viscosities and formulations of "VC" such as 3, 4 and 5, but all are essentially plastic dissolved with MEK or other solvents.

(Another word for that is "paint").

The other "VC" formulas use other solvents, such as VC4 which uses Ethyl Acetate instead of MEK. These differ mostly by how long they take for the solvent to flash off. But all of them are essentially acrylic paint.

All of these were originally developed for very large threads - as you would find on tank parts. That's the origin of VC3, going back to Vietnam.

Now, the obvious problem is, in many states, especially California, getting your hands on MEK to get rid of the VC3 on an install these days is a major PITA, because it's more regulated. However, it's available through Alliance Chemical, which sells on Amazon. And MEK is a far more effective solvent than Acetone. (Both should only be used in very well ventilated areas with no flame sources.)

[Biggy]

I often wondered why more manufacturers don’t use Spiral lock fasteners (taps and I think bolts also) for things when they do not want things to come undone too easily. I believe the tapped holes and bolts work using tapers on the threads of each that self lock together. When I was running a CNC mill at work we used Spiral lock taps on many different parts.