M4 Pic rail always loosening

[shootemz]

The pic rail on top of my M4 that came from the factory always comes loose after maybe 75 or 100 rounds. The gun is barely 3 months old. Any sights i have mounted becomes floppy, of course. All 5 screws come loose! I tried Permatex Blue Gel, but it didnt work - Im not even sure it bonded properly, even tho i prepared screws and holes with a degreaser - but didnt acetone. The threads are all intact.  Any expert advice? I see theres an idea elswhere that Loctite 243 [not 242] for aluminum to steel is proper for these tiny screws placement into the top of the receiver to hold the pic rail in place, but i dont kno what the screws and receiver metals are made of for the pic rail. Is this chemical answer the best way to go? Is there other tried and true options out there?

Thanks for any help.

[benelliwerkes]

Try some Loctite 620.

Edited November 16, 2022 by benelliwerkes

[shootemz]

Interesting...is it more glue like than a Blue thread locker? Im reading it becomes very hard? Is it similar disassembly as the heating techniques of the blue or esp red threadlockers? Also, thanks for taking time to share the pictures.

Edited November 17, 2022 by shootemz

[RxArms]

You can use blue loctight and torque to 16 in. lb.  Use brake clean or some other degreaser before using the loctight and you should be okay.

you don’t want to use Red unless you feel like heating up your rail if you ever want to remove it.

the receiver is aluminum, screws are steel.

Edited November 17, 2022 by RxArms

[shootemz]

5 hours ago, RxArms said:

You can use blue loctight and torque to 16 in. lb.  Use brake clean or some other degreaser before using the loctight and you should be okay.

you don’t want to use Red unless you feel like heating up your rail if you ever want to remove it.

the receiver is aluminum, screws are steel.

Thanks.

[shootemz]

Thanks to all for any other advice....

Edited November 17, 2022 by shootemz

[shootemz]

6 hours ago, benelliwerkes said:

Try some Loctite 620.

Thanks.

 

[ede2301]

I've had good luck with Rocksett in the past for a number of applications with both small and large fasteners.  It is removable if necessary, to apply just clean the threads on the fasteners and on the receiver and then apply to the fasteners and install with the proper torque setting.  It's about 12 bucks for 2 ounces but I'm still working on a 2 ounce bottle I bought like 5 years ago and it still works as advertised.  You can get it direct from FlexBar, Amazon, or Brownells.   

https://www.flexbar.com/products/rocksett

Give that a whirl, FYI a little bit goes a long way. 

[benelliwerkes]

Rocksett would work fine. It's a ceramic adhesive that can withstand 2,000 deg F. of temperature which is why many mfg.'s (e.g. SureFire) of silencers and brakes recommend it to secure the devices. Heat is not how the adhesive is de-activated though; use warm water and soak the parts to release the adhesive.

The picatinny rail steel screw threads have only 4 mm of engagement with the aluminum receiver threads......David v. Goliath. 

May have a hard time soaking the bulky receiver in warm water for de-installation.

 

[shootemz]

Thanks to both of you for the Rocksett info.

[RxArms]

Thanks @benelliwerkes that’s some great info there on that adhesive.