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DPP screws keep coming loose


RangerTrace

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I've been running the Stacatto P DUO with a Delta Point Pro since January and have had the screws come loose at least 5 times now.  STI has a Youtube video of Dave Dawson giving specific instructions on how to mount the optic using his DUO mounting system and I've followed those instructions each time.  The main point is have clean threads, using 1 drop of the supplied red locktite and tightening the screws to 24 inch pounds.  It wouldn't be that big of a deal, if I didn't have to check my zero each times it happens.

 

While cleaning the pistol yesterday, I noticed both screws were loose again.  So, instead of following the Dawson instructions, I used new Leupold screws and left the factory blue locktite in place.  

 

Any ideas?

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I have never had a problem using the Leupold factory screws in my CZ Multimount.  They never came loose.  I did have a problem on frame mounts, because they were not long enough to secure the sight on an Open gun.  Store bought M4 screws from hardware stores and big box stores were no good enough.  Too sloppy.  I bout a set of high quality, different length screws and mounted the DPPs using blue Locktite.  None have come loose.

 

Although not on the subject, I have had a problem with all the 5-40 frame mont screws supplied by everyone except Cheely.  I solved that problem by buying boxes of super quality screws from McMaster Carr.  They grip so tightly you don't even need Loctite.  Everything I've ordered from them has been first rate.  BTW, they almost always tell you the country of origin so you can avoid the cheap Chinese crap.

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1 hour ago, wdfwguy said:

I left the blue loctite on both of mine, and I stripped a screw on both of mine.

 Which threads were stripped?  On the screw, or in the threaded hole.

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4 hours ago, RangerTrace said:

I've been running the Stacatto P DUO with a Delta Point Pro since January and have had the screws come loose at least 5 times now.  STI has a Youtube video of Dave Dawson giving specific instructions on how to mount the optic using his DUO mounting system and I've followed those instructions each time.  The main point is have clean threads, using 1 drop of the supplied red locktite and tightening the screws to 24 inch pounds.  It wouldn't be that big of a deal, if I didn't have to check my zero each times it happens.

 

While cleaning the pistol yesterday, I noticed both screws were loose again.  So, instead of following the Dawson instructions, I used new Leupold screws and left the factory blue locktite in place.  

 

Any ideas?

 

Since you're in Texas, this probably isn't the cause, but Loctite is very slow to cure when exposed to temperatures under 70 degrees.  Loctite advises 24 hours cure time under 70 degrees F.

 

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Try this. Do everything you're doing, cleaning etc... Get yourself some Gorilla glue construction adhesive. Coat the bottom of the threads with your Loctite. Then put a coating of the glue under the head of the screws and the top part of the threads so the screws adhere to the dot body. Instead of the screws just holding by the threads in your base, they will now hold to the dot. It may help with the vibration too. They come apart very easy. This has worked for me very well, no problems of loose dots. Cleans up easy.

 

Good luck

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8 hours ago, zzt said:

I have never had a problem using the Leupold factory screws in my CZ Multimount.  They never came loose.  I did have a problem on frame mounts, because they were not long enough to secure the sight on an Open gun.  Store bought M4 screws from hardware stores and big box stores were no good enough.  Too sloppy.  I bout a set of high quality, different length screws and mounted the DPPs using blue Locktite.  None have come loose.

 

Although not on the subject, I have had a problem with all the 5-40 frame mont screws supplied by everyone except Cheely.  I solved that problem by buying boxes of super quality screws from McMaster Carr.  They grip so tightly you don't even need Loctite.  Everything I've ordered from them has been first rate.  BTW, they almost always tell you the country of origin so you can avoid the cheap Chinese crap.

 

ZZT  - which screws did you get from McMaster?  I think I want to grab some.  My dot mount screws for my open gun come loose now and again and I just assumed it was from cleaner and lube deteriorating the loctite over time.

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1 hour ago, zombywoof said:

Try this. Do everything you're doing, cleaning etc... Get yourself some Gorilla glue construction adhesive. Coat the bottom of the threads with your Loctite. Then put a coating of the glue under the head of the screws and the top part of the threads so the screws adhere to the dot body. Instead of the screws just holding by the threads in your base, they will now hold to the dot. It may help with the vibration too. They come apart very easy. This has worked for me very well, no problems of loose dots. Cleans up easy.

 

Good luck

Sounds like a good option.

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I bought a Glock that had stripped torx socket head screws due to red loctite. 

 I cut slots in the screw heads with a Dremel tool with a cut off wheel. Them I heated the screw heads with a small butane torch. I put the slide on the bench top and pushed down as hard as I could do the screw driver would not slip. I got them both out. 

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13 hours ago, clw42 said:

 

ZZT  - which screws did you get from McMaster?  I think I want to grab some.  My dot mount screws for my open gun come loose now and again and I just assumed it was from cleaner and lube deteriorating the loctite over time.

 

5-40 and M4x.7.  They seem to sell everything under the sun, so just look for quality.

 

https://www.mcmaster.com/fasteners/flat-head-screws-4/alloy-steel-hex-drive-flat-head-screws-7/

https://www.mcmaster.com/fasteners

 

Edited by zzt
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3 minutes ago, OPENB said:

How many times have you torqued the screws? I read somewhere that the DPP screws will lose their thread strength with repeated torquings. Maybe try a new set, not very expensive. 

We will see.  I tossed the originals Thursday when I installed the new pair of screws with the blue locktite.......When these work their way loose, I'm going to try the a drop of red on the threads and gorilla glue on the top....

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