Trying to sort out this Versa-Pack I bought recently. I've burnished the .410 full choke barrel's bore and there is no burr at the threaded hole for the bead. Still shoots a little high at 30 yards and the pattern is full of holes and much larger and 'open' than a full choke ought to be. Shoots slugs (2.5" Remingtons) just fine. A consistent 2" group at 30 yards that is about 3" high and 2.5" to the right (I can work with that!). But refuses to pattern Remington 3" #6 worth a darn. I've heard rumors that .410's don't like 3" shot shells and pattern better with 2.5" shot shells. Is this generally true? The 3 inchers are everywhere here but the 2.5" are very hard to find in my locale. This is the first .410 I've messed with, generally sticking with the 12 and 20 guages. The .410 seems like a whole 'nother animal. Any help would be appreciated, thanks.