YES. A 20 gauge is more than capable of hunting pheasants. I took my new 20 gauge Browning Cynergy O/Uon my annual trip to South Dakota this year. It was light to carry all day and had no problems knocking down birds out to 35+ yards. My South Dakota group of 13 guys : 5 have 20 gauges ( Browning, Weatherby, Remington and Fausti- 4 O/U, 1 pump); the balance use 12 gauge semi-autos(Browning, Benelli, Winchester andRemington).

Note: Up until last year when I bought my Cynergy, I never hunted or trap shot with a 20 gauge (only 12 gauges). It did take a lot of practice on the trap rangeand sporting clays courses to get use to how light it could whip and also not letting the clays get out to far.

Good Luck
MC2