To all:
I have been getting asked repeatedly about torque specs for these new rings. The torque required to achieve the same clamping load/force changes with screw size and thread. I am not an engineer, however I have access to world class ones. The numbers I am posting below come from a lead engineer of a major DOD contractor that does exactly this type of work doing the equations/math to arrive at these numbers while he had the rings in hand- let’s call him D.O. Then we mounted and shot them as such.
It interesting that when doing the math on a bunch of different rings- they vary wildly in their clamp force using manufactured recommended torque. So a scope company saying “14-16 in-lbs on rings” is utterly useless. Some brand of rings will put twice the clamping force into the tube as other brand of rings. There are rings out there that at 15 in-lbs you can smack the front of the scope and make the scope slide in the rings. There are rings that at 15 in-lbs provides the clamping “crush” force as other rings at 25 in-lbs. So we had to come up with a baseline. We chose NF Ultralight rings as the baseline because they are extremely well vetted and proven. Using Nightforce Ultralight rings as the baseline, to achieve an equivalent clamping force on the scope; UM rings need 28 in-lbs on the UM ring cap screws to equal 15 in-lbs on the NF rings. 34 in-lbs on the UM cap screws equals 18 in-lbs on the NF rings. Also, using the “K” value of blue loctite or a paint pen- DOES NOT materially add to the clamping force. It’s about 1 in-lb more. Oil causes noticeable changes in “wet” torque values, Blue Loctite and especially paint does not- it’s not as slippery and does not dramatically reduce friction over clean, dry screws.
I was mounting the scope, while D.O. was still working through the math/conversions/whatever, I used 15 in-lbs on the ring caps and knew instantly that wasn’t it- I told him “dude, 15 in-lbs feels like nothing by hand, it’s going to move”. He asked what I thought, and said probably twice that torque to feel the same as NF rings. When he finished, that’s what came out. 34 in-lbs on UM rings feels in the hand like 18in-lbs or so on normal rings.
So using the data from the D.O., this is what I would suggest with UM Tikka rings-
If you have a strong scope- NF, SWFA, Trijicon, S&B, etc- 34 in-lbs with Loctite. That equals 18 in-lbs in a standard NF ring.
If you have a scope that is “fragile” or one that is susceptible to binding the erector due to ring crush- 28 in-lbs with Loctite on UM ring cap screws equal 15 in-lbs on standard rings.
So far I am using 45 in-lbs on the base screws to attach it to the rail. That amount of torque feels about right and quick math said that should do. The base screw torque is subject to change.
