Right. The idea behind chokes is to have the optimum concentration of shot in the biggest dense circle possible at a predicted target range.
Here is a primer on the topic. http://www.chuckhawk...e_on_chokes.htm
A lazy way is to shoot a dusty backstop and see how big your dust cloud is and more importantly get a feel of the size where the dense area is in relation to your sight picture. I find that if people including myself are missing clay, it helps a lot to throw a milk jug out there and roll it around for a few shots to get your sense of aim to match what actually happens.
That page also has some extremely technical articles on choke performance.
http://www.chuckhawk...2c.shotguns.htm (Scroll down to BARRELS, CHOKES AND PATTERNS:) Don't get mad if you find that math and science contradicts your opinions or proves that you've been sold some gunsmiths that makes no measurable difference. There was an interesting article there at one point that proposes a different patterning method than the normal 30" circle system.
The big idea is that if you know the size of your target area, and the range to shoot, you find the most open choke that is mathmatically certain to put at least 3 pellets within the size of your target.
Short story is shoot your chokes and find what puts the most evenly concentration of lead in the area you expect to shoot.
There is a tremendous amount of snake oil in choke marketing. In short, choke design was scientifically optimized a long time ago by W.W. Greener.(Something like 1860 IIRC) Current models are just minor variations on compromises between the Greener pattern and space requirements. Wad type can matter as much or more now, and some chokes are designed to work with wads, while others are designed to strip wads early. The only thing which can say one works better than the other is the lead on target.
I have been using the winchoke adapter cobra sells and am pretty pleased with the extended useful range I get with the tube marked "full". I also enjoy using a rifled paradox choke for slugs.