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Czechmate CMore mount screws loosening, help


JWBaldree

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I can't keep two of the three screws that attach the CMore mount to the frame tight. For the first year and a half, a dab of 242 blue would keep everything happily in place. Now the two outside screws loosen after one mag, and that's with 271 red trying to hold them in place. Everything gets fully degreased, twice, with brake cleaner, and the red is allowed to set up for 36 hours plus before firing. Considering the rear hole is blind, I don't think oil contamination from the slide rails is at fault. Outside of TIG welding the mount to the frame, any one have a suggestion?

 

Thanks in advance.

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If you have a set of M4 x .7 tap and die, use the tap to clean the threads on the holes and the die to chase the threads on the screws. Degrease them, use blue loctite to reinstall screws and let it set for 24 hours.

 

I have done this for screws that keep on loosening up. Sometimes, even brake cleaner cannot thoroughly  remove all the residue between the threads. 

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No cracks visible, plus last weekend was a fresh chapstick tube of red loctite. I'll look for shellite and a tap and die.
Would be great to hear the update on this after you're done.

Sent from my SM-N950U using Tapatalk

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11 hours ago, Matt1 said:

Clean the holes as described. Use shellite to degrease and use a fresh bottle of red loctite


Sent from my iPhone using Tapatalk

What is Shellite might be a auto spell check screw up lol

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Had same problem with my Czechmate sight mount.  Had to chase the threads and then clean and re-clean them multiple times (including the threads on the screws) with brake cleaner, and then the Loctite cleaner.  Used RED Loctite and have not had an issue since.  The least little bit of oil / grease in the threads and the Loctite will not cure properly.  I use the liquid and not the stuff that is in the "chapstick" tube.  The other option to the Red is Green 632 Loctite.  I have used that in the past to mount compensators on other guns, but will warn you that you will definitely need to heat up the screws if you should ever need to remove them.

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Update: I thoroughly cleaned the screws and holes with brake cleaner and acetone, and on the advice of an old  machinist used Loctite 7649 primer and 290 green. Finally made it to the range today and dumped 200 rounds as fast as I could. Everything is holding just fine. The machinist said that Loctite 240 / 260 / 270 series were all designed with 1/4< screws and bolts in mind, whereas 290 was designed for screws as small as #2's. I dunno, but so far so good. I also had a suggestion for Vibra Tite from another old school shooter who swears by the stuff. https://www.vibra-tite.com/industries/firearms/  I might try that in the future for grins and giggles. Oh, and new screws came in from CZ USA, just in case.

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