hi recently purchased a al391 tenkys beretta semi auto and used it twice so far. was shooting at recent shoot old guy behind me said i was shooting over the top so lowered barrel by 2 foot at 20 yards below target he said i was still shooting over the top? does any one else have this problem and if so how did you over com e it? i sold a beretta 302 and could hit most things with it so its not a case of a semi auto please any advice greatly welcomed. also does any one know if you can purchase shims for the gun that are bigger than the ones in the gun? thanks mark.