cajungeo et al,
I confess that my experience with Mini 14 bases (and I am referring to those that are designed to fit the non-ranch versions) is limited. I suspect that you may be onto something more general though. I am holding my B-Square base with rings in my hand and it certainly does not look or 'feel' like steel. It weighs a little more than 4.5 ounces, is very rigid but is non-magnetic. It is sort of a satin finish although, like your piece, was referred to as "stainless" by the firm that I bought it from. When I originally purchased it I just assumed it was an aluminum alloy. I wonder if the slightly less expensive version offered by the same manufacturer, which was described as "blued", was made of the same material, as opposed to steel, but finished to look "blued" thus implying steel. So, in this case, as well as yours, the description referred to finish, not to material. In any case, the B-Square mount worked rather well on those occasions that I used it. I don't know if it would have been as pleasant to use if it actually had been made of steel with its additional weight. Oh, and thank you for the warm welcome!