ysr-racer is most likely thinking of a sporting clays target crossing at 16 yards. Brad, this is ATA or PITA trapshooting. You are standing 16 yards from the trap with a slightly on edge view of the top of the target quartering away. Light Modified will work most of the time when shooting only 6 or 8 targets. ;^)
I like IM, 2 3/4 Dr.Eq.(1145 f/s), 1 1/8 oz of #8. Start with practicing with Mod and tighten up as you get better.
Here's my answer (it's evolved over the years), "Pick one, any one will do".
But I'll add that it's best if your choke provides for a tight enough pattern to allow your breaks to be read. You should be able to tell if you've centered the target (smoke) or shot the tail off it or the nose, the bottom or the top. This will tell your brain how to correct so you'll center them all. cls
1 1/8 oz #8 1145fps IC choke will bust the snot out of em. As will a light modified, a modified, an improved modified, a light full, a full, an extra full, a super full, and a .650 turkey tube. Oh yeah I forgot skeetI and skeetII. Cylinder might be a little too open....... Pick your poison!
Practice with the tightest choke you are comfortable with. Then when it's time for registered/tournaments use a modified tube of high quality. As someone stated earlier, you don't extra points for smoking the target, just breaking them!!
Why not shoot a full in practice and a looser choke for registered? Because you won't be getting the feedback that the full choke provides precisely when you need it - when your score counts.
Another thing to recognize - when you shoot singles you are actually practicing for handicap. Smoking a singles target gives you the confidence that when you step back to handicap yardage you can point the target properly. And with a full choke you get the feedback at handicap distance where it is even more important to know where you are hitting.
Put the full choke in, and leave it in. Unless you take it out to put the extra full in.
It's relative to the speed in which you shoot your 16 yard targets. I get smoke w/ #2 K-80 choke, .019 (mod) constriction. Won a State shoot w/ that combo, and broke 4 other 200's that year. I don't shoot that much, but I practiced w/ that choke as well. Always practice w/ the choke your going to shoot.
The most popular MYTH in trapshooting is that an open choke is gonna buy you some extra targets with the fringe of the pattern. When you spend some time at a pattern board at the distance you break targets with several chokes, you will realize that the more open choke has a weaker center core pattern but no improvement of pellet holes to the outer fringe. Sure, if you are shooting SKEET you need a more open choke but remember that 30 yards is about average distance for a very quick shooter from the 16 yard line.