Conflicting torque specs

[General Geoff]

On that note, threads are stretched, as they should be once set to torque value, and they’re meant to be replaced if removed. I doubt most guys are writing the ring manufacturers to request new fasteners if they’ve removed a scope and re-mounted.

Steel screws can be stretched to an elastic deformation zone, whereupon when they are unscrewed they will return to their original dimension and can be safely reused and re-torqued again to elastic deformation. This is why you can reuse your car's wheel nuts dozens of times without replacing them or the mounting studs.

Only certain fasteners in certain applications specify torque-to-yield, and must (should) be replaced after every use. Gas carrier key screws on AR BCGs are one of them.

 

[Gun-Reck]

It's not a matter of "coming loose". It's a matter of over torquing.

When you wet torque a fastener that was intended to be dry torqued, the bolt will stretch MORE than it would for a dry torque of the same amount of force. This is because you have less friction, so the fasteners will continue turning longer as you approach the specified torque value on the wrench...

If one understand the asymptotic nature of frictionless thread deflection - tight, is.

As is over tight.

Elastic and Plastic are material terms.

 

[General Geoff]

If one understand the asymptotic nature of frictionless thread deflection - tight, is.

No such thing as frictionless thread deflection in the real world.

Again: Grease (or any other thread lubricant) modifies ideal torque values, it does not magically eliminate the necessity to use a torque wrench, if you want reasonably accurate, repeatable bolt stretch.

 

[RetiredUSNChief]

On that note, threads are stretched, as they should be once set to torque value, and they’re meant to be replaced if removed. I doubt most guys are writing the ring manufacturers to request new fasteners if they’ve removed a scope and re-mounted.

This makes an excellent case for using LocTite and a common rail system if you intend to change out optics. Think of it as gluing the screws in place rather than stretching the screw threads.

Yes, properly torqued hardware CAN be reused (other potential damage aside, of course). If the hardware is not stressed beyond its yield strength, then ductile failure (plastic deformation) will not occur.