Torquing Scope Ring Screws

South Pender

South Pender

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I've often wondered what to make of the torque values recommended for the scope mount ring screws (not the base screws). Should we assume that these suggested torque numbers are for dry screws or are they for lubricated screws? I never use a thread locker like Loctite on the ring screws (although I do use Loctite purple on the screws attaching the bases to the receiver), but ring screws often arrive with the mounts with very light oil on the threads.

So what do you guys recommend? Should these ring screws be de-greased before torquing them to the recommended tightness or should they be used as they come and torqued to this level? The two approaches will lead to different levels of tightness.
 
How much are the different levels of tightness? Would a couple of extra inch lbs really matter?
I always start at 18 inch lbs , right out of the packaging.

I think calibers matter as well.
I had a set on a 300 WM , specs called for 18 and the scope moved.
Moved up to 20 and it was GTG.
 
I use a Weaver brand inch-pound torque driver - is set up with screw type bottom and bar indicator to set torque - has marks in units of 5 - so one side is 15, 25, 35, etc. and other side is 10, 20, 30, etc. Best I can do is get the indicator bar "close" to what maker calls out - I just did a set of Dual Dovetail Leupold rings yesterday - Leupold calls for 28 inch pounds - so I set the thing more than 25 and less than 30 - maybe closer to 30. Torqued screws until the thing "clicked" - to be seen if anything moves. I had previously used a lapping bar to ensure the two ring bottoms were aligned to each other - should minimize marks or damage to the scope tube.
 
Potashminer said:
I use a Weaver brand inch-pound torque driver - is set up with screw type bottom and bar indicator to set torque - has marks in units of 5 - so one side is 15, 25, 35, etc. and other side is 10, 20, 30, etc. Best I can do is get the indicator bar "close" to what maker calls out - I just did a set of Dual Dovetail Leupold rings yesterday - Leupold calls for 28 inch pounds - so I set the thing more than 25 and less than 30 - maybe closer to 30. Torqued screws until the thing "clicked" - to be seen if anything moves. I had previously used a lapping bar to ensure the two ring bottoms were aligned to each other - should minimize marks or damage to the scope tube.
Click to expand...

Yes, I have the CDI torque screwdriver, and it has similar units from 5 to 40 in.-lbs. So I can drive the screws to the suggested tightness--for Talley vertically-split fixed steel mounts, for example, 30 in.-lbs. for the bottom screw (that clamps the rings to the base) and 20 in.-lbs. for the top screw. But 20 in.-lbs. for a screw with some lubrication on it represents a fairly different tightness (greater) than 20 in.-lbs. for a de-greased screw. When we're dealing with clamping scope rings around an aluminum scope, one approach will clamp the scope more tightly than the other, and we sure don't want to put too much pressure on the scope tube.
 
I have never seen how to translate a "dry" thread torque spec to a "wet" thread torque spec - any insight how much difference that is for equivalent "clamping force"? I just do not know. Has been my practice about forever to put a drop of blue thread locker in hole of receiver, then torque in the base screws to whatever the maker calls out as torque spec - I think they usually imply a "dry" thread torque, but I notice some new ones have a blue or red paste on screw threads - so I presume their "torque spec" anticipates that stuff being used on the thread? I have never added anything on scope ring holes - nor have I ever "de-greased" the screws, as they come from the package. Most all "previously used" stuff gets the threads "straightened" - I do chase the holes in a receiver with a tap, and then run the mounting screws into and out of a "gizzie" to clean and straighten those threads.

Edit: is not actually a gizzie like sold by Brownells - is simply a 1/4" thick angle iron with multiple threaded holes - I use that to set height on small screws that I want to grind or cut off to be shorter. Is also an 1/8" thick (or maybe is 0.10" thick) one here, somewhere.
 
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Industry standard to torque any fastener is lubed....not dry.

Any self locking fastener should have the prevailing torque added to the torque specification.
 
Maybe I should try to clarify things a little. The torque does not change between wet (lubricated) and dry screws. 20 in-lbs. wet is the same torque (radial force applied to wrench or screwdriver) as 20 in-lbs. dry. What changes is the amount of clamping force generated by the screw because less of that 20 in-lbs of torque applied to a lubricated screw goes to overcome thread friction. I don't have any data on the difference in clamping force between wet and dry screws, but it will, of course, be greater for the wet (lubricated) screw. In other words, 20 in.-lbs. of torque on a lubricated screw will put more pressure on the scope tube than will 20 in.-lbs. on a dry screw. It's one reason why most scope-mount manufacturers recommend against using a thread-locker (which functions as a lubricant) on ring screws. Perhaps a reasonable compromise would be to twist the ring screws in a tightly-held cloth and use a dry Q-tip on the screw holes, but stop short of actually de-greasing them with a solvent.
 
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Loctite on the bases-receiver connection. Never on the scope ring screws. Scope rings and the screws should be thoroughly decreased before installing. 20”lbs on the rings and between 40 and 50 “lbs on the ring-base connection (depending on the materials used to make your rings and bases. Aluminum and cheap pot metals 40 is good. For real steel rings and bases, you can go higher.

So to answer your question, why would your threads be “lubed” on scope rings?
 
Canuck65 - where did you get those torque numbers? I just looked on Warne website - they are suggesting 25 inch pounds torque maximum for their base screws into a steel receiver and 15 inch pounds maximum into an aluminum receiver - that is MUCH lower than what you posted? Another reference that I have - from the Weaver scope installation kit - says 30 inch pounds torque for base screws into steel receiver and 20 inch pounds into aluminum receivers - so is higher numbers than Warne posts. But Warne is clear for installer to refer to the firearm maker for specific torque numbers for the base screws - Weaver says to refer to "Owners Manual" - I understand the Warne website posting is to indicate what they consider to be maximum torque when installing their bases, and the Weaver pamphlet to indicate what they "recommend" for their units, if nothing found in "Owners Manual".
 
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I've never gone over 30 on a base screw or over 22 on a ring screw.
Purple loctite on base, ring dry.

I always think more than that and those tiny 6-48 screws are gonna a break.
An exception is leupold windage screws..gone to 45 on those
 
Canuck65 said:
Scope rings and the screws should be thoroughly decreased before installing.
Click to expand...
Can you give us a reference for this?

I can see it for the rings, and I do de-grease the inside of the rings along with the scope surface (I also shake some rosin onto the inside of the rings to enhance resistance to slipping; it was suggested by Greg Warne with his older Warne rings and makes complete sense.) But who is suggesting de-greasing the scope-ring screws?

Canuck65 said:
So to answer your question, why would your threads be “lubed” on scope rings?
Click to expand...
They could come with a coating of oil to prevent rust in storage. In addition, using a thread locker (not recommended) on them will provide lubrication.
 
Potashminer said:
Canuck65 - where did you get those torque numbers? I just looked on Warne website - they are suggesting 25 inch pounds torque maximum for their base screws into a steel receiver and 15 inch pounds maximum into an aluminum receiver - that is MUCH lower than what you posted? Another reference that I have - from the Weaver scope installation kit - says 30 inch pounds torque for base screws into steel receiver and 20 inch pounds into aluminum receivers - so is higher numbers than Warne posts. But Warne is clear for installer to refer to the firearm maker for specific torque numbers for the base screws - Weaver says to refer to "Owners Manual" - I understand the Warne website posting is to indicate what they consider to be maximum torque when installing their bases, and the Weaver pamphlet to indicate what they "recommend" for their units, if nothing found in "Owners Manual".
Click to expand...

I think that Canuck65 is referring to the torque applied to the screw that clamps the rings to the base, not the screws that secure the base to the rifle's receiver, which, I agree, should not be torqued more than about 25 in.-lbs. I usually go with 22-23 in.-lbs on the base-to-receiver screws and use purple Loctite as well.
 
That could be what he was referring to. However, a few days ago I installed Warne rings 215M and that one's little card called for 25 inch pounds torque for the two screws that clamp the ring to the scope base, and then 25 inch pounds for the two screws on top of each ring - vertical split with a recoil bar that goes into the recoil slot - so not all are "the same" - for sure, I see the Weaver kit suggests 30 inch-pounds for the "cross bar or clamp screws" with steel rings, and 25 inch pounds with Aluminum rings.
 
Aluminum receivers and tiny little 6-48 holes have threads that are unforgiving.
An inch/lb too much and you'll be ordering over size 6-48 from Brownells and taps as well
 
I only clean base/rail threads and screws, I don’t bother with rings. I torque everything to factory specs but use the rings as they come. Have never had any loosen, blue loctite on base/rail screws but none on rings.
 
Another factor to consider in this context is the number of threads of engagement for the screw. For a reasonably large number, like, say, 6 threads of engagement, higher torque values are appropriate than would be right for screws having, say, 3 threads of engagement.

Here's something I ran across that bears on this discussion:

http://bordenrifles.com/wp-content/uploads/2021/11/ScopeBaseTorqueSpecs.pdf
 
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South Pender said:
Yes, I have the CDI torque screwdriver, and it has similar units from 5 to 40 in.-lbs. So I can drive the screws to the suggested tightness--for Talley vertically-split fixed steel mounts, for example, 30 in.-lbs. for the bottom screw (that clamps the rings to the base) and 20 in.-lbs. for the top screw. But 20 in.-lbs. for a screw with some lubrication on it represents a fairly different tightness (greater) than 20 in.-lbs. for a de-greased screw. When we're dealing with clamping scope rings around an aluminum scope, one approach will clamp the scope more tightly than the other, and we sure don't want to put too much pressure on the scope tube.
Click to expand...

South P. , I have Talley rings & bases on all my rifles and start
vertical & horizontal rings @ 2 n / 18 in. lb the bases 3 n / 27 in. lb wet or dry.

2n is quite the torque on small threads.

Then adjust if required ( not required to date) .
...skwerl
 
skwerl said:
South P. , I have Talley rings & bases on all my rifles and start
vertical & horizontal rings @ 2 n / 18 in. lb the bases 3 n / 27 in. lb wet or dry.

2n is quite the torque on small threads.

Then adjust if required ( not required to date) .
...skwerl
Click to expand...

Yeah, that sounds about right. For the vertically-split rings (the ones I use), that 18 in.-lbs. is close to what Talley recommends for the smaller top (8/40) screw. For the larger (10-32) bottom screw, they recommend 30 in.-lbs. Your torque for the base-to-receiver screws is probably fine, although I don't torque them quite that much--usually about 22 in.-lbs. with purple Loctite.

I'm now thinking that Talley's recommendations are for the screws as they arrive in the box with the rings--not de-greased, and definitely not with thread-locker.
 
South Pender said:
Another factor to consider in this context is the number of threads of engagement for the screw. For a reasonably large number, like, say, 6 threads of engagement, higher torque values are appropriate than would be right for screws having, say, 3 threads of engagement.

Here's something I ran across that bears on this discussion:

http://bordenrifles.com/wp-content/uploads/2021/11/ScopeBaseTorqueSpecs.pdf
Click to expand...



On 60 degree threads only 3 threads on each side of the compression point do all the work.

The other threads on said fastener are for alignment purposes only.

An ex-fine thread is capable of a higher torque value than a fine or coarse pitch thread.
 
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