Torque spec on rings by Leupold or Nightforce - Dry or with oil?

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An interesting statement in that link:

"...in addition the accuracy of a torque wrench is normally no better than +-25%."

That's rather strange, since the link is called "Engineering Tool Box".

In the engineering world, NO TORQUE is EVER applied by an uncalibrated torque wrench.

Quality torque wrenches, calibrated to an accuracy specification, and periodically calibrated thereafter.

Calibrated torque wrenches with an accuracy of +/- 1% are not unusual.

The engineering standard also provides for calibration periodicities, as well. A link I researched says this is ISO 6789 (International Organization of Standardization) with a minimum calibration periodicity recommendation of 5,000 uses or 12 months.

If you're using a Harbour Freight torque wrench which you've never calibrated and keep buried under a pile of tools in your tool box...yeah, I'd say +/- 25% would be optimistic.
 
One I don't think I've seen mentioned is scale. After some comments that there's no way exceeding small torque values like 15 in-lbs could break a fastener: remember how small the fasteners are. I broke a screw in a USO base because I hand tightened before getting the torque wrench on and... it was a very small screw. Snapped right off where it should when over-tightened.

Substrates and fastened items also matter, as partially mentioned. And, it doesn't mean the components are badly designed. I sometimes work with (in design, etc) electronic components on big machinery. They often have the torque rating molded right into the electronic case in the hopes techs will notice, because even the first hand-tighten in the manner of bolt-engine-together will destroy the electronic box and often the seals, the connectors, or even the PCB inside.
 
I think you’re dreaming if you think Harbor Freight torque wrenches would be within 2.5%. 25% may be generous

Years ago when I was a regional service manager with Deere & Co we put on a service school for the dealer mechanics. We had multiples of a number of tools. The variation was pretty mind blowing

I remember we had the little antifreeze testers with colored floating balls that showed freeze point. Some would float one ball, some using the same batch would float three. We threw them away
 
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