Thread lock not holding 338

[bearcatrp]

When I got my 110 338LM FCP, I made sure to use blue thread lock on the rail threads. Was at sisters place this past weekend shooting steel at 500 yards. Shot about 50 rounds. Rail became loose. Came home today, removed my scope and found all 4 screws were loose. Snuuged them up, took one out at a time to clean threads and reapply blue thread lock and tighten them again. Is there something better than blue thread lock? Don't want to use the red thread lock. I know the recoil is pretty stout but didn't think all 4 rail screws would break loose. Suggestions?

[RustyShackle]

Clean the screw holes and screws! Probably oil(s) preventing the thread locker from doing its job.

[Zero333]

I've had great luck with Weaver 20 moa rails for Savages and Remington's. I've never had one loosen and they have a integrated recoil lug that actually works.

I like using the White Thread Sealant. It's always hanging besides the Thread lockers in the stores. It's thread locking capabilities are stronger than the blue locker, yet weaker than the red locker.

However... Don't be afraid of using the Red thread locker. Even tho it says it's "permanent", it really is not at all. Just makes fasteners harder to undue.

[Robinhood]

Rusty has a good point. clean all of the oil out of the threads.

[Mb1500]

Red thread locker is not JB weld like many people make it out to be. It's all I've ever used. A firm impct easily breaks it free.

[bearcatrp]

Will try the blue one more time. If it fails, will try the red. The rail screws strip so easy would figure the red would almost insure a strip. Never heard of white Thread Sealant but will check it out. Thanks guys.

[tobnpr]

Is Savage using #8 screws on the .338 action? On heavy recoiling magnums I recommend the 6's be drilled/tapped for #8's

[RC20]

We need to get down to some basics here.

A head bolt has lube on it (sometimes other slickum but often lube these days)

Its bathed in oil all the time, it does not come loose and it does not have thread locker.

You have one of two problems.

1. Your screw have been stretched and are now in the plastic instead of elastic range. Replace screws, use a torque wrench if you were the only owner, while torqueing is not exact by feel most mechanics know what the feel is close enough not to stretch a faster.
A fastener that has gone plastic can only be held on by welding. All the thread locker in the world is not going to change that.

2. Your base has an issue. Down in the recess its not flat. Its giving. Kind of doubt it but its possible. It should be obvious if it is.

[tobnpr]

^^ This
Suggest you just replace the screws, since you've had two "failures"- probably because you've overtightened; the "instinct" that more torque/preload is better isn't true with small scope base screws in particular. Particularly with torx heads, it's easy to overtighten past the screw's yield point- and permanently stretch/loosen it. Around 20 in/lbs or so- if you don't have a torque screwdriver use a short key and go 1/8 turn past "snug". Threadlocker for sure, initially acts as a lubricant and increases clamping force. I'd stick with blue, after degreasing the screws and tapped holes. Oils interfere with the curing, and decrease its strength.

Base screws on heavy magnums are subject to large, shear "shock" loads- which tend to want to loosen fasteners. If Savage is using #6's on the Lapua action (it's different than the standard large shank) they've done the calcs and decided it's adequate but I'm more comfortable with #8's.

[jglover_81]

Purple locktite is what I usually use. Stronger than blue but not as strong as red. However I agree that the screws should be replaced