It sounds like the stock is too high for the rings chosen causing you to press hard into the stock with your cheek weld in order to get a good sight picture.
Lower the stock via allen screw adjustment or if you are already as low as the stock will adjust, get higher rings.
Everyone is different but I have a 30mm tube in a PEPR with a reflex sight on a 45 degree Picatinny. I can have a good cheek weld for the scope AND roll the stock to see the reflex sight picture. I had to raise the stock slightly to get scope and reflex in a good sight picture with a good check weld.
Lower the stock via allen screw adjustment or if you are already as low as the stock will adjust, get higher rings.
Everyone is different but I have a 30mm tube in a PEPR with a reflex sight on a 45 degree Picatinny. I can have a good cheek weld for the scope AND roll the stock to see the reflex sight picture. I had to raise the stock slightly to get scope and reflex in a good sight picture with a good check weld.