Actually, I have had a set of rings that were poorly made (Will not disclose the brand). During installation, I thought something was different than normal, and when sighting in, I discovered the scope was slipping. Since this rifle was only a 270 Win, it was very odd. The tops were completely flush with the bottoms, and no amount of tightening would remedy the problem.
Being a "never say can't" kinda' guy, I found a roll of double sided tape and lined the rings' tops and bottoms. I used those rings on that scope for a dozen or more years!