If the thread title, "The Best/Most durable lifetime steel scope rings", is taken without qualifiers, then the mounts made by David Lloyd for his rifles are without equal.
Lloyd built the mounts individually for each rifle he produced, mostly on M98s and Sakos, with the majority of rifles chambered for the .244 H&H, a cartridge he developed and sold to H&H. The mounts were so strong that they warped the action a bit.
Unfortunately, you have to buy a rifle to get a mount. (Bill Ruger and Roy Weatherby owned David Lloyd rifles.) Wikipedia has an entry for David Lloyd, riflemaker.
Below is a photo of a Lloyd rifle with a Lloyd mount: Steel! Very durable! Lifetime!
The image is from a rifle for sale in Scotland by precisionrifles.com. gunstar.co.uk usually has some David Lloyd rifle listed.
