ORIGINAL: Simp
The first bird I shot was with #6's at 43 yards. Just know what your gun can/will do though.
Agreed. If you are using a "hevier than lead" type shot, then it certainly has enough energy at 40 yards. The main thing is to make sure you know both your limit and your guns limit. Most likely, the #6 will pattern better than the #5 shot and you will get the added benifet of having more pellets in the shell...