Get the Rifle regulated to the open sights and then work up loads
for the scope and / or the factory should set up the scope in the QD mounts
so that it shoots at least the right barrel to POA.

If you regulate the gun to the scope then the gun is effectively useless with
open sights.

Also, once the gun shoots to the sights, if the scope QD mounts have been
done correctly, then it should align itself with the open sights and as long as it
doesn't move you should be able to shoot the same rounds.

My Merkel 375 worked out fine.

500 Nitro