What does the locker have to do with it? They either bind at full lock or they don't and the locker has nothing to do with how far the wheels are turned.
My understanding: The u-joint shouldn't bind more or less in a turn with locker on or off but the longer distance covered by the outer tire in a turn causes the inner to scrub on a hard surface with the locker on (or vice-versa). U-joint bind occurs when the axle turns enough to cause this, which my on may not happen depending on the particular set up.
