pat- dont fret it. i think you were too tightly choked. i would go back to cyl if you are getting birds in that close.
the long read- keep in mind that with technology improvements to things like shot cup and buffered shot, you are getting increasing pattern densities.irc, modern loads already pattern at 10-15% btighter than 30 years ago.
if you mic'd your tubes (i did) yo will find that they are off a bit from manufacturing. so what. as long as they shoot straight, it all comes down to the rube goldberg machine that runs between our eyes, brain, arms and fingers anyway.
each step in chokes is about a 10% increase in pattern density figured at 40 yards. (choke meanings between makes is confusing too. like overbored guns like your old mossy or berretta's extrema are already like 5 over everyone else). its better to use the diameter to compare apples.
some math: figuring a 30" shot cone at 40 yards, at 15 yards it would be about 8-10". mod is about 70% density, and at 15 yards with a MOD choke, you will either pulverize the bird if you are 'on' or miss by a mile.
with my sbe2, i have found out to 25-30 yards, i do better with cylinder and kill plenty of tough pheasants and waterfowl. i use imp-cyl after that and use mod only for really long range. i did try a imp-mod an full last year shooting sea ducks (the size of canadians) with 3.5" kent fasteel 3's, but shot so poorly that i went back to mod and smoked them. i am talking at 40-50 yards
i have some scans from a mcintosh book for you on dialing in your stock and fine tuning the point of impact. you pattern the gun at 16 yards. adjustments to the stock via recoil pad shims, or leather strips to the top or sides of the stock are easy due to the geometry. iirc, its 1/16 per inch off center... it will make more sense when you read it. once you get point of impact on, then worry about pattern percentages. some guys hate mcintosh. i think he has the smarts and data to back up his 'science'.
POI and patterning took me a 2-3 hours on a saturday afternoon using 4 wally whirled tablecloths cut in half and a 4' square of plywood. maybe a box of 8's, then a few of my choice 6's, 2's, and BB/TTT to make sure it all worked ok.
i would not be surprised if you pattern a bit high, which is not a bad thing. most of the time many of us miss low and away anyhow. i would leave it alone if it did.
lastly, i would not get hung up on actually counting. its more of a touchy-feely thing. does the pattern look good? if a bird was in the circle, would it be hit with enough pellets?
dennis
(not to many around here). i was so pissed. I've have been dying to get one of those for years. A drake wood duck is on my list of waterfowl to mount. 
I cleaned up on the dove and early teal within the last month. And they are a whole last faster and smaller than those honkers.
