Bob,
I had a friend that bought a Spanish 28 ga from the Vegas show that both barrels patterned high. He couldn't figure it out. I looked at the barrels. They were slightly arched up.

I have straightened bent sxs barrels in a press. The entire assembly can be bent or straightend as desired.

Have a look at you barrels. Turn the gun on its side and check them. If they're straight, work on the stock as recommended. If they're bent, find a smith who knows how to straighten them.