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

[dogcaller]

My first RDS platform is a LTT92. I purchased the pistol from a member here and then purchased the RDS slide from LTT directly. I've had it for about a year, mounting an SRO. I would estimate 1500-2000 rounds on the RDS slide. I noticed a slight wiggle with the base yesterday during dryfire, which means that I will need to detach both the sight and the mount to fix it. This is the third time I have had a sight or mount come loose in the last year. The round count is not that high--it's just frustrating. It's the biggest reason I decided to have my G-17 direct milled for a Steiner MPS--hoping to alleviate this very issue with the crossbolt mounting system. That being said, I'm loving and really concentrating on the LTT, and would like to continue with it.

I have assiduously followed both the directions from LTT (the first and second time) and the best practices advised in the comprehensive thread here on PF, including using Vibratite / Loctite as described.

Each time, I have cleaned out the screw holes as well as I could, again, following directions. In addition to the hassle factor, I worry that mounting and remounting will eventually cause damage to the fine threads drilled in the slide.

Is my experience different than yours, and, if so, do you have any advice?

Thanks!

[Pnut]

I have an STI Tactical in .45 with an SRO and had the same problems. The mounting plate that fit between the slide and SRO would always come loose after a few hundred rounds.

Someone here suggested I bed the plate to the slide with a product called E6000, which is essentially an industrial grade rubber cement. It can be found at most hardware stores. I tried it out and it’s worked great. I’ve only put about 1000 rounds through it since the bedding, but it hasn’t budged yet.

Someone also suggested using VibraTite as a bedding compound, but I haven’t had a need to try it yet. Both products would do essentially the same job… securing the plate to the frame, but also absorbing the shock of the moving parts because of their elastic nature.

[dogcaller]

I appreciate that, Pnut. Will need to check that out.

What's the best way to clean this gunk out? I've used alcohol, plastic picks and pipe cleaners in the past, but I'm not sure that it's getting all of the residual threadlocker residue out. Is there anhy risk/benefit to using carb or brake cleaner? Other recommendations? Thanks

[DaBigBR]

I'd try acetone first. I usually put it on a pipe cleaner and vigorously work over the threads. Acetone will strip a lot of stuff alcohol will not in my experience. It evaporates extremely quickly as well.

[YVK]

Answering your question in a generic way, in 6 or so years running dots on CZs, Glocks, and SIGs I've had optics or mounts come loose twice. A dovetail mount on a Glock 48 and either a DPP or SRO, don't remember, on CZC plate on my Shadow 2. I don't use the Vibra, only blue loctite. No idea about LTT mounting solutions and how it compares to others.

[DaBigBR]

Also, don't reuse screws. Go on McMaster Carr"s website and get the ones you need in bulk. A bag of 50-200 (depending on specs) will be $8-$16. Take a quick inventory of what you have for optics and plates and such and get a bag for each. I know C&H is subject to some mixed feelings on here, but their plate listings provide exact screw specs, which is nice.

[TCinVA]

In class I see mounts failing far more than the optics themselves.

A good first step is to understand how thread lockers work:

https://pistol-forum.com/showthread....er-information

...because a lot of people out there have absolutely no idea what they are doing. They mean well, but they are hopelessly wrong.

Once you understand a bit about how fasteners and thread lockers work, you know what variables you need to control.

Re-examine your cleaning process prior to mounting. Whatever thread locker you use, it's crucial that you carefully degrease and decontaminate the threads both in the hole and the fastener. When it comes to removing old thread locker and other gun, I find pipe cleaners really kind of suck. I've taken to using precision brushes from McMaster-Carr:

https://www.mcmaster.com/4905A12/
https://www.mcmaster.com/4754A782/

...because they are small enough to fit inside the threaded holes on most slides and durable enough to allow you to actually scrub well enough to remove a bunch of crud.

So if you handed me your gun and asked me to re-mount things here's what I'd do:

1. Obtain new fasteners for the plate if at all possible.
2. Using a dropper or something similar, put some 99% isopropyl alcohol in the screw holes of the slide and let it sit for a couple of minutes.
3. Using the precision brushes linked above, scrub the living bejeezus out of the screw holes in the slide. This will probably destroy the brushes...but I'm fine with that.
4. Use some compressed air to blow out the holes, then go back to steps 2 and 3 a few times.
5. While letting the slide dry, get a small tray or an old bit of tupperware you don't care about and put enough of the isopropyl alcohol in the tray to soak the fasteners. Let them soak for a few minutes.
6. Using a toothbrush and some tweezers, give the fasteners themselves a good scrubbing. (Note - I wear nitrile gloves when doing all of this to keep oils from my skin from being a problem)
7. Set the fasteners out on a clean shop towel or something to dry.
8. Once the threaded holes and fasteners are completely dry, I will apply a little Vibra-Tite VC3 on the threads of the fasteners. I will use a fine paintbrush (that has been cleaned in the alcohol) to force some of it into the recesses of the threads. Let this sit for 5-10 minutes.
9. Apply a drop of VC3 into the threaded holes in the slide. The drop will sit at the very top and not go down into the blind hole unless poked with a toothpick or metal pick to allow the trapped air out.
10. Affix the plate to the slide and then begin to thread in the fasteners.

If you've used the right amount of thread locker, a little bit of it will start to ooze out around the head of the fastener when you torque it down. This is key, as it helps hold the fastener in place as well. A good application fills in the gaps between the thread surfaces and any small gaps between the screw head and the slide.

11. Clean up any excess or spillage that happened on the slide. (Q-tips, paper towels, etc)
12. Set the slide somewhere it won't get subjected to temperature extremes for at least 24 hours.

Using that exact process I've mounted optics to my shotguns and to multiple Glock MOS pistols without anything coming loose for literally thousands of rounds of shooting. I've set my Glocks aside in favor of running my customized M&P's, but prior to that they went through just shy of a combined 25,000 rounds without the plates budging an iota.

[TCinVA]

I'd try acetone first. I usually put it on a pipe cleaner and vigorously work over the threads. Acetone will strip a lot of stuff alcohol will not in my experience. It evaporates extremely quickly as well.

Acetone is also worth a shot as a cleaner/degreaser. Ultimately anything that will break up oil and other substances we don't want interfering with the performance of the thread locker and won't leave a residue is cool. Loctite makes their own cleaner-degreaser that would also work.

But finding a way of getting good strong mechanical agitation into those threaded holes is a huge boon to keeping plates mounted solid. Anything you can use to facilitate that is a good idea. I've found the aforementioned precision brushes work well and I've been known to resort to actual dental tools to pick out larger hunks of schmutz so I can scrub.

[Archer1440]

VC3 is crap for this application. Full stop, end of story. Use blue Loctite, preferably 248 solid.

(I wrote a long treatise on how and why, but deleted it. There's plenty of other threads on the subject.)

[TCinVA]

I've not had VC3 show up as "crap" for this application in my guns or in client's guns. (To the point where one client who had his optic fail had to buy a soldering iron to remove the CROM from his 1301 so he could ship his busted Aimpoint back) In fact, I've seen fewer failures with it than I have of Loc-tite. VC3 seems to be slightly more forgiving as it doesn't set up with a hard crystalline structure like Loc-tite does, which is a little easier to thwart. Over-application seems to be the worst problem with VC3.

But either will work well providing you observe the holy rituals of decontamination prior to use.

Whatever you choose to use, the majority of success is in the preparation.