I would say that most of what I have read contradicts JonnySax's suggestion of using flavor extract, which I've heard sucks. Why not just add more raspberries?
Also, I've used blackberries in my beers in the past, and they definitely produced less of a berry-like flavor. It was hard to describe, but it almost produced a velvety/chalky flavor.
Also, I've used blackberries in my beers in the past, and they definitely produced less of a berry-like flavor. It was hard to describe, but it almost produced a velvety/chalky flavor.