i install a lot of scopes. It is very important to check the alignment of the rings using alignment bars. Sometimes i'll use the honing bar even if the rings perfectly align. This removes any milling marks on the inside of the rings.

In the past three or four years i've seen several scopes that were bent by rings that were not properly aligned. One of those scopes was a very expensive Kahles that was installed by a local "gunsmith".

The made in China rings are sometimes badly out of alignment and require too much honing to straighten out.