net should have 1 pound of lead per foot.
Try to start with a small net 6' radius till your use to it. I have a 10' & just purchased a smaller net out of frustration. Check out this site - There was a recent thread about cast nets.
If you going after only LARGE adult bunker, I'd get a net with large mesh (1" or 1.5") 10' radius, with about 1.5 lbs of weight per foot. You want a large fast sinking net. Be careful throwing it into a large school of adult bunker, because if it opens fully you wont be able to pull it into the boat yourself...(just speaking from experience)...but one good toss near the edge of the school will give you enough baits for a full day of fishing.... but you need a large fast sinking net as the fish are usually moving, or at least they will be when you throw the net, thats why smaller (6') nets tend to miss alot....... its like trying to shoot ducks with a rifle, you can do it but a shotgun works much better.....
try east coast nets. He is in staten island and makes nets designed for bunker. He will even show you how to throw a 10 footer with ease when you go and get your net. He will also show you how to lift the net when you hit the jackpot on the throw.... pull 1/5th or so over the gunwale at a time until they are all in the boat. I got an 8 footer from him and throw it fairly well, the first season I ever threw one in my life. His name is Charlie Kay