Hmmm, sorry to confuse you about chokes. Here is the deal, they are screw in tubes that constrict the shot as it leaves the muzzle. They control the spread of the pattern. With a wider choke, you get a wider and less dense patter. With a tight choke, you get a dense narrow pattern. In order from tightest to most open:
Extra-full
Full
Improved Modified
Modified
Improved Cyl.
Skeet
Cyl.
For trap I use a modified. I believe in skeet the going is Imp. Cyl. The extra full is for turkeys. Play with the chokes -- and pattern your gun at 35-40 yds will all that you have.
Let me know if this is clearer -- it took me a while to understand chokes too.
Hueco