blue Loctite not working to hold torque

Professor Doolittle

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How important is it for the threads to be oil-free before using blue Loctite? I'm shooting .300 Norma mag and the pic rail mounted directly to the Stiller action comes loose after every 150 rounds or so. What should I do? How do I get the oil off the threads? I tried alcohol before but the threads end in a wall so I can't be sure I've got all the oil out.
 
Denatured alcohol or brake/parts cleaner and then compressed air work for me. If using brake cleaner make sure you have all other areas and materials removed (stock) as it can discolor or eat into plastic. Verify your threads are good on the screws and run a bottom tap in the holes. If you don't plan to remove the rail, you can go with a more permanent loctite as well. Also ensure you are torquing to specs. One other thing, shake the bottle of loctite for a coupel of minutes before you use it to get it mixed. Good luck.
 
Are you using Loctite 242, by chance? If so, try Loctite 243 and let things cure for at least 24 hours before shooting. Maybe Vibratite VC3 (apply to threads, let congeal for ~15 minutes before screwing) would work better?

 
Acetone on,.. a Tooth Brush for the Screw threads and a Q-Tip,.. in the Holes !
As a former Gunsmith of 25 years experience and mounting Hundreds of Scopes.
Blue Loctite AFTER, a thorough, De-greasing / Drying.
My Customers, shot Big Game, World wide with, NO "Issues",.. EVER.
 
Last edited:
How important is it for the threads to be oil-free before using blue Loctite? I'm shooting .300 Norma mag and the pic rail mounted directly to the Stiller action comes loose after every 150 rounds or so. What should I do? How do I get the oil off the threads? I tried alcohol before but the threads end in a wall so I can't be sure I've got all the oil out.
Have you tried Acetone and air? I'm not sure I'd play with the red stuff until nothing else works, perhaps not even then. Just think out loud.
 

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