Using iron shafts that are too heavy?

In simple terms whats happens when using iron shafts that are too heavy?

I've currently got lightweight shafts in my irons (dynamic gold SL x100)
They weigh around 110 grams I think
They're working very well and no intention of changing anytime soon

But was curious if I picked up a club with say for example dynamic gold S300 shaft (130 grams) what difference could I expect to my shots?