If you do your job, are reasonably sure where your gun shoots and how it patterns, buckshot is effective out to at least 50 yds. I've taken and seen taken too many deer at this range to doubt buckshot's effectiveness. My advice though if you're going to use buckshot is to use the 3" or 3-1/2" magnums if your gun can handle them. You want to throw as many pellets downrange as possible. Also pattern your gun to see which size gives you the best combination of density with the largest pellets possible. I have nearly always found no. 1 buckshot to meet those requirements.
