Gunsmithing Torque values for vortex scope vs arc rings

[Okiegunner]

I have a gen 2 razor that says the maximum torque value for the rings are 18 in/lbs.

arc m10 rings says 50 in/lbs for rings and base screws.

my question is do i follow vortex or arc specs?

I was thinking follow vortex but i wasnt sure if the clamshell design of the arc rings changes how much pressure the rings put on the scope.

dont want to follow vortex and it be too loose and dont want to follow arc and it be too tight and damage the scope.

Anyone have any experience with this or know the science behind it?

 

[Gene Poole]

I would think that Vortex is assuming Vortex rings. It would be silly to specify a torque for a ring they know nothing about.

50 in-lb seems high, but I don't know anything about arc m10 rings.

 

[Okiegunner]

I agree with you there but I think what voretx means by that torque value, is pressure that the rings put on the tube its self.

 

[Gene Poole]

in-lb is a torque unit, not a pressure unit. It is meaningless unless associated with something that is twisting. Without knowing the geometry (thread pitch, diameter, friction coefficient, bearing surface, etc,) specifying a torque value is meaningless.

 

[Sheldon N]

4 smaller screws vs 1 larger screw changes the equation. I run 45-50 in/lbs on my ARC M10's with no issues or ring marks.

 

[47guy]

ive had an ATACR,gen2 pst,gen2 razor and now a minox ZP5 all in M10s all at 50in lbs and like Sheldon no issues or ring marks.

 

[Blowby]

ARC rings require tq values based on their design. All my scopes look perfect without any ring marks on all the guns ranging from 50-60 inch pounds. This is just to keep the action, base and ring tq values the same. One tool, set to hit them all, with the same value. Just my method of madness.

 

[Dave62677]

55 in-lb on my previous M10 ARC ring, no ring mark, Rock solid.

 

[Okiegunner]

ARC rings require tq values based on their design. All my scopes look perfect without any ring marks on all the guns ranging from 50-60 inch pounds. This is just to keep the action, base and ring tq values the same. One tool, set to hit them all, with the same value. Just my method of madness.

not a bad idea!

 

[Okiegunner]

4 smaller screws vs 1 larger screw changes the equation. I run 45-50 in/lbs on my ARC M10's with no issues or ring marks.

I was thinking that. The arc ring put pressure all the way around instead of smashing it between the top and bottom.

 

[diverdon]

The ARC is a bigger screw, it needs more torque.

 

[LRI]

No, no, no. Has nothing to do with size of screws or the scope even. It's the design of the ring.

Easy way to think of this:

ARC ring, it's like a hug. A big ol bear hug. The clamping pressure is distributed over the circumference of the scope tube.

Other rings that clam up via top/bottom or side/side is like a fat girl sitting on a PB&J sammich. Stuff gets squished being the point.

You can run up to 50lbs inch on ARC rings with no consequential damage to the tube. If you try that with conventional rings, it'll likely mark up or distort the tube. You'll also likely kill a screw hole or two as the 8-40's and 8-32's used by most won't put up with that.

Your making a great choice. ARC rings are the shizzle.

C.

 

[diverdon]

No, no, no. Has nothing to do with size of screws

Chad, it would be a great idea to break out your machinery's handbook before you make that pronouncement. The courser pitch on the bigger screw Ted uses will take more torque to develop the same tension. The rest of your explanation seems correct.

 

[LRI]

"Needs" more torque. (you said that) No. It does not need it. It may very well tolerate it better, but it would do the same job with less. The ring design allows a higher clamping load to be applied to the optic's main tube. Because the design is better and does this without killing the scope, a larger fastener is required because the smaller stuff (typical of scope most rings) would fail in short order. (if subjected to the same tensile load applied at an arbitrary torque value.)

-edit: One screw clamping the gull wings of the rings does a better job than two in this case because you can tighten it without any bias. (simply to mean your not pinching one side of the ring more than the other) Again, because of this, a larger diameter fastener is called upon.

The tensile load of a fastener is what ultimately determines its failure rate. A screw/bolt/stud is for all practical purposes behaving much like a spring. "squishing" stuff together. They yield when that value is exceeded. Be it deformation of the threads or just turning itself into multiple pieces.

 

[wapiti16b]

"Needs" more torque. (you said that) No. It does not need it. It may very well tolerate it better, but it would do the same job with less. The ring design allows a higher clamping load to be applied to the optic's main tube. Because the design is better and does this without killing the scope, a larger fastener is required because the smaller stuff (typical of scope most rings) would fail in short order. (if subjected to the same tensile load applied at an arbitrary torque value.)

-edit: One screw clamping the gull wings of the rings does a better job than two in this case because you can tighten it without any bias. (simply to mean your not pinching one side of the ring more than the other) Again, because of this, a larger diameter fastener is called upon.

The tensile load of a fastener is what ultimately determines its failure rate. A screw/bolt/stud is for all practical purposes behaving much like a spring. "squishing" stuff together. They yield when that value is exceeded. Be it deformation of the threads or just turning itself into multiple pieces.

This is correct ! , ARC rings are DEFINATELY THE SHIZZLE ! , I suspected that 50"lbs was way too much and set mine to 40" lbs , nothing has moved on my 308 HOT 168 G loads as of yet . I've since mounted the scope ( Vortex GEN II ) on my 300WM and plan on loading 210 grain through 230 grain bullets and if the scope moves I will let everyone know , I suspect it will not due to the even distribution of pressures .