Thread: Scope rings - Steel vs Aluminium

Aluminium is generally softer than steel.
We are talking about clamping something soft (aluminium rings) to something hard (steel receiver).

There are many possible variables, but the gist of it is; under repeated recoil it is possible for the aluminium to mar or peen under the superior hardness of the steel to a point where they can become loose.
If you look at old alumimum rings that have been on a rifle with a reasonable amount of recoil, sometimes you will see that the recoil bearing surfaces of the rings are deformed where they have been repeatedly subjected to pressure by a much harder material.

IMO, alumiunium rings require a greater contact area with receiver in order to mitigate the potential for the softer material to deform.
Both have their place. Some of the best mounts in the world are made of aluminium (spuhr), but they also have huge contact areas between the steel and aluminium.
I would be perfectlu content with for example steel optilocks which dont have much of a contact patch. But I would not want aluminium optilocs as the contact area would be too small to have good longevity without deformation.