The pattern is not wider at all, I don't think, necessarily - that just depends on choke. Now to the extent it may be backbored and you cut it at that point, then yes the pattern will be bigger because the muzzle is bigger at the exit point. But a shorter barrel does not necessarily translate into wider pattern.
Beyond that, I answered this question in your thread at thehighroad.org.
Beyond that, I answered this question in your thread at thehighroad.org.