Flat dumbbell bench

[myosaurus]

you can try powerlifting fashion flat bb with narrower grip and elbows tucked it. I've had same problem(partial torn bicep long head, proximal). I'd keep my lumbar and lats contracted throughout the whole time bring the bar just below the pecs. I also keep the shoulder and scapula far back into the bench and lift the sternum to de-emphasize the shoulder.

 

[BlueDevil]

I think ATW might be on to something. I'm wondering if your compensating with your delts. I do that myself.

Also, where is the pain in the shoulder on flat barbell bench and what kind of pain is it? Are you doing any warm up exercises for your rotators before benching?

 

[gentao]

ive been having the same problem. my pain is rite where the acromion is located.