Posted: 4/29/2026 9:51:11 AM EDT
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I've got optics mounted on 3 pistols. They all either had vibratite or lock tite applied to threads before the were torqued. If I want to check to make sure they are still tight, can I just use torque driver set to 15 in lbs and turn till it clicks? Is that going to break the bond of the thread locker and cause it to loosen? Or do I need to pull the screws clean and then re torque with thread locker. Maybe over thinking it, what do you all do? |
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In the past I have set my torque driver a tiny bit lower than spec and click. I don't set it to the actual torque limit as you run the risk of overtightening with repeated torqing to spec. You could always re-install if it really bothers you. The best option is to just paint reference marks on your screws once torqued. Then you have a visual reference if they have loosened. |
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I use the ultra-fine tip version of this for witness marking, both for screws and QD mounts. https://benstoegerproshop.com/sharpie-oil-based-paint-pen-marker-for-optic-installation/ Also make sure that your screws have enough thread engagement, especially if you're using a plate. The short factory screws that came with my RMR HD wouldn't hold with my particular gun and plate, and the long ones prevented the slide from cycling. I ended up ordering intermediate-length screws with the correct countersink from Calculated Kinetics. https://www.calculatedkinetics.us/collections/gun-accessories/products/optic-hardware |
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Originally Posted By laughingman: Good point on the checking below torque spec. I'll try that.... Thanks Just trying to confirm they are still tight. Have had one screw shear off and that was not easy to get out. I've had several sheer off. Gunsmith says that it's because people tend to use too long of a screw and it either bottoms out or interferes with the slide itself. You won't notice it at first but it eventually loosens and then sheers off. |
 
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That stuff worked terribly for me. It was a massive pain to get a nice line without it smearing everywhere. |
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Originally Posted By Piratepast40: Afraid I can't be of much help. Torqued mine to 5 in lbs as recommended in the manual and also used used red locktite. Came loose after about 50 rounds. I've been having terrible luck with optics on My M&P so watching this thread to see what others recommend. I always clean the screw threads with isopropyl alcohol and a paper towel. I almost always see a bunch of gunk get cleaned off. I also use alcohol on a tiny micro swab (buy on amazon) to clean the screw holes the same way (you can also twist a corner of the paper towel to swab out the screw hole). Loctite can't stick to dirty or greasy screw threads. Also use blue Loctite on optic screws, never red. I've broken or stripped screws using the red stuff. The blue stuff is plenty strong enough if you use it correctly. Also don't apply too much. One drop on one screw, then wipe the two screws together spreading it evenly on both. It should just lightly coat the threads, not be globbed on. I've never had an optic screw unintentionally come loose using these techniques. |
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Originally Posted By SM0KESCREEN: In the past I have set my torque driver a tiny bit lower than spec and click. I don't set it to the actual torque limit as you run the risk of overtightening with repeated torqing to spec. Most fasteners have a torque range. Install them with torque near the upper end of the range and you can use a torque wrench to later to verify that they are still above the minimum. That would still work whether you are using Loctite or not. |
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You absolutely will not continue to tighten a propperly totqued and blue loctited screw by going back over it with a Wheeler Fat wrench at the same torque value you installed with. Even if you do it a hundred times. Anyone who tells you differently is lying. The loctite is stronger than the torque used to install or the torque needed to remove. |
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I wouldn’t worry about it. 15in lbs with loctite is good enough for most handgun mounted optic. I haven’t had one come loose set to 14-15 in lbs with Loctite. On the flip side I followed one manufacturer’s recommended torque setting of 10in lbs with Loctite and the optics kept coming loose after about 200 rds. And this was on a .22. Set it to 15in lbs and it hasn’t budge since. I guess I’m different than a few here. I have always set mine to 1-2 lbs more than the recommendation. If the recommend 14in lbs I set it to 15in lbs. never a problem. |
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Originally Posted By Piratepast40: Afraid I can't be of much help. Torqued mine to 5 in lbs as recommended in the manual and also used used red locktite. Came loose after about 50 rounds. I've been having terrible luck with optics on My M&P so watching this thread to see what others recommend. What plate are you using because 5 in/lbs seems awful light? In my M&P I have the RMR mounted using a Calculated Kinetics plate and so far it's stayed tight in the 600rds I've put through the gun since installing. |
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I had a persistent issue with my mounting screws working loose. Vibratite and blue locktite didn’t solve. Even carefully torqued didn’t help. Did some length checks and the mounting screws were maybe .001”-.002” too long. Short enough the sight felt solid after torquing but just long enough to bottom out without properly tensioning the threads. I filed off about .005” and bluelocktited them. Been solid since. I wouldn’t keep rechecking the torque. Witness marks are better. Problem with rechecking is over time your torque wrench may be ‘just’ moving the screw enough to break the locktite bond. No torque wrench gives an EXACTLY repeatable value. There’s always a tolerance band. |
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