Not at all. Go to www.hevishot.com
or www.remington.com, look into the ballistics of hevi-shot vs. lead. 6's hit hard at 40yds and beyond.
Two of my birds last year were killed at over 40 yds. Actually almost 55 steps on one, and 53 steps on the other. I shoot Remington Hevi-Shot 3.5 #6's. I have only had one bird that tried run after shooting it. The reason being that my pattern was so tight at 15yrds, I missed. But got him on the second shot.