Also try different ammo if you have some, that can affect point of impact. When I was having problems hitting birds with my Greener Martini shotgun I found that a 1 oz load at 1175 patterned 3" low and 3" to the right. A 1 oz load at 1250 patterned dead center.

I have become addicted to English hammered shotguns to the detriment of my wallet.