The Contessa Picatinny rail fits nicely on the Blaser R8 interface and is tightened down with 3 Nm which makes for a secure attachment.
However the rail itself is made from investment casting and the rail doesn't meet the MIL-STD-1911 standard as the spec dimensions regarding width is 21.2 mm -0.13
However the rail itself measures between 20.88 and 20.95 mm width which causes the Picatinny rings not to tighten down correctly and leaves them with slack so you can move them back and forth on the rail within the rail lug cutout. On top of this the rail is not straight but has a slight bend/curve in it which would cause a bending tension on the scope tube.
I give it 2 stars for the perfect fit to the Blaser barrel interface, other than that the rail doesn't work as it's supposed to.
Response from EuroOptic: Andreas,
We are very sorry to hear you were not satisfied with this Contessa Picatinny rail. While we can assure you that this item, as are all Contessa rails, are produced via 5 axis CNC, we will look further into the fact that this rail may have been out of Spec. We have never encountered a Contessa rail that was under spec, but we take your claim seriously. We have sent a return label in order for you to return this item free of charge