HK USP Tactical Overtravel Stop Threadlocker

[einherjarvalk]

I figured out earlier today that my USP Tactical's overtravel stop screw has been slowly working itself loose since I bought it. I reset the screw, witness marked it with red paint, and dry fired about 50 times before checking and seeing that, yes, it was in fact unthreading.

While it is thankfully unthreading towards "more overtravel" and not "gun doesn't go off," I do want to fix this. I'm assuming some threadlock will get it fixed in short order, but Loctite Blue specifically says not to use it in applications where metal is contacting plastic. What other options do I have for threadlocking such a tiny set screw?

[GJM]

I had my USP Tactical screw back-out such that the gun wouldn’t fire when shooting support hand only. (Why, beats me, but I must have been on the trigger slightly different support hand only) My solution was to unscrew it fully, and toss the part into the tundra. Was always confused why a “Tactical” pistol would have a failure prone part like that.

[CCT125US]

First thought is plumbers tape. If mechanically inclined, remove the trigger and drill and tap a set screw into the side of the trigger. Not sure if there is enough real estate on the edge of the trigger though. Pictured is a 4-40 tap pointing at the set screw, with a size 43 / .089 bit. Not suggested on any serious use gun, as GJM mentioned. Just showing an option.
25751

[einherjarvalk]

The USP trigger is far, far too thin to install a second set screw on from the other axis.

This is primarily a range gun and as I said before the screw likes to unthread in a manner that just increasea overtravel rather than locking up the trigger. I do not intend to remove the set screw - all I’m looking for is an appropriate threadlocker that can wick into the screw while installed. Blue loctite explicitly says it is not for use in contact with plastic; Loctite 424 seems to be better suited but also appears to be near identical in formulation to super glue. Can anyone shed light on that?

My other option is to just reset it after every range trip since it's walking into the trigger and not out of it, but that seems pretty counterintuitive to consistency.

[OlongJohnson]

My solution was to unscrew it fully, and toss the part into the tundra.

Litterbug!

[Artemas2]

Maybe?
https://www.amazon.com/Permatex-19920-Plastic-Threadlocker-10/dp/B003ERTZWA

[einherjarvalk]

So, update time:

I did some more digging and found that Bill Springfield suggested the use of Loctite Blue for this specific issue over on HKPro. Not content with his word, I also called HK customer service, who said that's what they'd suggest starting with as well.

I've given a tiny - like, "dabbed on from the tip of a sewing needle" tiny - amount of Loctite Blue on the outside area of the screw threads in the trigger face and am letting it cure now. Hopefully this fixes the problem. If not, a new trigger is like $15 and I'm willing to bet HK CS will replace it gratis since it came this way from factory.

[Alembic]

Sorry to be a dick, but from my personal experience with said gentleman, the phrase "suspect source" comes to mind.

[OlongJohnson]

So I remember this old thread, Google it, and guess who the OP turns out to be? GJM

http://www.hkpro.com/forum/hk-handgun-talk/133160-caution-bill-springfield-hk-trigger-work.html

[GJM]

Bad experience

[einherjarvalk]

Springfield's opinion wasn't enough to get me to loctite the screw on his own. HK CS giving me the go-ahead did.

That said, I ended up having to pull the screw halfway out, apply threadlock just behind the set screw head, and reset it to where I wanted it to get it to actually stick. A few hundred dry fires later, and what's left of my witness marking shows the screw as not having budged.

I'm also much less concerned about the chemical impact of the loctite on the trigger itself; I realized while doing the second application that the trigger is actually metal and just coated in polymer, not unlick the frame of the gun itself, so the set screw threads probably run directly through a steel "spine" insider the trigger hook anyway.

[Spartan1980]

If it moves again try this.

https://www.amazon.com/Vibra-TITE-213-Threadmate-Threadlocker-Degree/dp/B008D6GHY6/ref=sr_1_1?s=automotive&ie=UTF8&qid=1524974037&sr=1-1&keywords=vibratite