243 Loctite (surface insensitive) on clean external & internal threads. Same blue loctite on clean surfaces of receiver/ring base. I use a in-lb torque wrench. For cleaning I use PVC solvent.
Problem with the short fasteners we use is there's for practical purposes no fastener stretch.Long fasteners stretch (like a spring) when torqued/tightened properly. This helps with fastener torque retention.
The condition driftless describes (spring in the ring) could provide torque retention.
For assemblies where short fasteners are needed, it is common to see bolted joint designers us spring washers (Belleville washer) to help retain fastener torque.
You seem to have a pretty solid understanding how bolted joints work; not many do. Stretch like a spring is what keeps joints tight, with or without Loctite.
Something to consider though in this application that's different than most bolted joints - the spring in the ring screw joint isn't the screws (in most cases), it's the scope tube and/or the rings. With an air gap between most top and bottom rings, usually we're stretching or compressing the bolted parts before the fasteners.
