Oil Screws on Mounts?

EccentricJackal

Well-Known Member
Hi All,

I have just ordered some Leupold Mauser mounts for my .308 Parker Hale, and had a quick look at a video guide (I think by Leupold) which said you can use Loctite on the screws, but they recommend no loctite, but gun oil instead. This seems counter-productive, as surely we are looking to stop the screws moving once they are in there? I understand this would help with anti-rust but wouldn't Loctite achieve the same without the potential for loosening over time?

Any advise or experience would be appreciated.

Thanks,

Ryan
 

EccentricJackal

Well-Known Member
Thank you for the video.

Would you expect it to be okay long term with the oil then, and not prone to wriggling loose? - I wouldnt be using a torque wrench so probably wont get the full benefit of adding the oil.

Cheers,

Ryan
 

Heym SR20

Well-Known Member
well i removed a set of mounts off a rifle that have been on there for 30 plus years and were still tight. A well fitting screw driver and a firm turn and out they came. The trouble with Loctite is that you risk real damage if you ever need to remove the screws, given that can need to use quite a bit of torque to get them out. You risk stripping screw heads and or hx heads etc. Which then requires drilling out and using a screw extractor etc. You don't need a lot of force - just tight - as per the video.

The whole principle of a screw holding firm is that the screw is under a bit of tension and all of the male threads are thus tensioned against all of the female threads. Unwind the a thread of even a small screw you actually have quite a large surface area. If all of that surface area is gripping it will hold properly. A little bit lubricant helps that grip to be applied across a large surface area. With no lube, just the high points grip and gall so it will feel tight, but its not. And yes even on a perfectly fitted thread there will be high points.
 
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palmer_mike

Well-Known Member
Great, thanks for your help, I'll go with the gun oil then!

Trying to avoid overthinking it on details but will this stuff be suitable or should I get a non aerosol version?

http://www.yorkguns.com/parker-hale-express-gun-oil-aerosol-150-ml

This is what I use at the moment.

Cheers,

Ryan
if that's what you have available and you want to use gun oil on the screws I'd use the spray.
id probably spray a bit onto a cloth and then transfer the oil from the cloth to the Screws, but that's just me..... I'd feel more in control of the amount applied that way.
 

Southern

Well-Known Member
I don't use Loctite. I very lightly oil the screws, and tighten to specs, but no more, because they are so small.

Normally, on larger bolts, if you oil the threads, and want to preload the bolts, or not have them loosen under vibration, you must torque them 20% higher than dry threads.

I bought a mint Steyr Mannlicher at a deep discount because someone had used the wrong thread locker and broken off two screws. I had to drill them out with a diamond bit, heat them with a micro torch, and use a tiny extractor to back out the hollowed screws.
 

EccentricJackal

Well-Known Member
Thanks Southern, I'll take care to get them as close as I can to the spec in the absence of a torque wrench/driver, as I don't fancy my chances of getting a snapped bolt out!

Ryan
 

Southern

Well-Known Member
You have to follow the bolt manufacturer's recommendations, because some bolts are meant to be tightened up dry (like a wheel lug nut), and some lubricated ( like in a steel truss). There is no rule of thumb.

You are correct, 10-ring, in that lubrication lowers the thread friction, which means that less wrench torque is required to overcome it, and more of it goes to overcome washer friction and head pressure clamping force. If you want the same bolt preload, you would lower the torque by some percentage for a light oil, and more for a moly grease ( like on a steel truss bracket ). For a bolt into the cast iron block of Diesel engine, you would always use a certain specified thread lubricant. For stainless bolts in an aluminum hub of a fighter plane, no lubricant whatsoever.

But the bolts on scope mounts are small and don't need to be torqued for preload, so much as to remain in place under shear forces of recoil. Because oil will lower the thread friction so much, I have found that it is best to tighten the screws by feel, which usually comes out a bit higher. If the manufacturer specified a torque for a screw with very light oil, use that - no more an no less. The reason I use a very tiny amount of light oil is because I don't want vibration to loosen the screw. I only put the oil on the first half of the threads, and wipe off any excess. I don't want it squishing out on the head. This is a big advantage when you need to break the screw loose. Even with a lubricated thread or dry fine threads with no corrosion, the breaking torque can run 2.5 times the fastening torque. On a small screw with the wrong sealant or some corrosion, it could be 5x or more, enough to shear off the screw.

I am no expert, but I used to own a company which sold torque wrenches up to 600 ft lbs, to all the NATO military, particularly aircraft and commercial airliners, as well as building steel buildings to 30 stories. I just remember a few things I picked up, No. 1 being to always check with the manufacturer.

PS: Loctite and others thread sealers act as a lubricant while you are tightening the screw, reducing thread friction and increasing preload on the bolt. So don't use the wrong Loctite or too much torque!

However you prepare the threads, it is wise to always use a penetrating oil prior to breaking them free.
 
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patterdale

Well-Known Member
I always use a small wrap of Ptf tape on my rifles and never had them come loose my rifle has heavy use daily and its on a 270 hope this is something different to use and will never lock it so you will be able to remove them
 

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