There is a reason the Beretta is so heavy, you said it yourself that is was a competition gun. I have my Beretta set up at just shy of ten pounds, and it does quite well on the skeet range. After 500 birds in a weekend competition, the weight really soaks up recoil, and it also builds up your muscles after a while.
I usually get out my Ruger 28ga if I'm headed bird hunting, or one of my small gauge 1100's. They feel like feathers after using my target gun. I have a little .410 SxS Huglu that I plan to bird hunt next year with a bit.