A 2 3/4" load will kill a turkey at any distance a 3" load will. Perhaps even farther. The 3" loads aren't more powerful, they just have more pellets. The velocities of the shorter loads are usually higher because you've got about the same amount of powder and a lighter shot charge. I've had 2 3/4" loads pattern better than 3" at 40 yds. It depends on what your gun likes. My personal criteria for a good pellet count is a minimum of 20 in the head/neck at 40 yd. Any load that will do that consistantly will drop a turkey, no matter what the length.