8 inches make 20 cm. If we suppose that the distance between bead and rear sight is 50 cm, you ought to get a 2 mm higher bead. However, such a high bead is easy to break, and personally I'd prefer to lower the rear sight if possible.

But first of all you should try the same load, as the gun was regulated with. High hits may indicate that the rifle is sighted in with heavier bullets - 286 grs are standard. Information about that should be written in the test protocol from the factory. If you don't have got the protocol, you should send the factory an e-mail about the issue.

I had the same problem with my stone age 8x57IR drilling, which once was sighted in with 220 grs bullets. As only 196 grs are available today, my fresh loads hit about 6" high @ 100 metres. A new 0.75 mm higher bead solved my problem.

Fritz

P.S. Recknagel has fine sights http://www.magnumhansen.com/Recknagel_Katalog_5.pdf