I weighed five 20's with barrels from 28" to 32" and they ranged from 6lbs 2oz to 6lbs 12oz. All O frames. I am also searching for the ideal (for me) grouse gun. I have conclued that it is the gun (or guns) I am comfortable carrying 7-9 miles in the woods and that shoots where I am looking with a hurried mount from various foot/body positions. At this point in my search the leading contenders are a straight grip 28 gauge repro with the Q1, Q2 26" barrels and the longer LOP and a pistol grip 20 gauge repro with the 26" ic/mod barrels. I have a couple original Parker 20's knocking on the door in 28 and 20 gauge. I'm committed to more research this off season.
Good luck in your quest for the Holy Grail.