Why I am I so much weaker at flat barbell bench then flat dumbbell bench press? I can lift the 150lbs dumbbell press 6 to 8 times but when it comes to barbell I strugle at 275, can anyone explain that and tell me how to fix it ? I switch my bench press up one week I do barbell the next week i do dumbbells and for some reason I am really week at barbell.