Actually Salopian I think it's the other way round if anything.
No mate Salopian is right. They are not cylinder, mod etc, but his "most open choke" has 2 thou of constriction, where a cylinder choke has none. The reason for this is, he found that with just that little bit of constriction, the pattern more to his liking, than without.
A U2 is like a quarter choke, which should then be about 10 thou, but it is 12 thou.
If Hamster or Aspire want to know more about them, click the link in my sig because I reviewed them on here. Also notice the other bit under that link
RE: Patterns. I did pattern my U1 chokes when I got them, to use for Skeet. I do not have these patterns available as I did not know I might need them!
Anyway. I compared them to my extended Briley SKT chokes, from about 16 yards to 25 yards. U1's are designed to be "optimal" at 25 yards, so the closer patterns were obviously tighter, but throughout..only the first couple of patterns had "hotter" centres at about 16 and 18 yards, and the rest of the pattern was fairly even, out to the edges. This is what continued to happen up to the 25 yard patterns, very even around the edges with no "hot" centre" This was with steel 9's which is what I use for skeet.
Pattern plates can only tell you so much though. The best way to see how your gun shoots a string, is to shoot a simple away target.
With the Muller chokes, the patterns are good yes...but it is this along with the other benefits, that makes them so different form other chokes, and no other choke can offer
all of these things.