I used a teague ported for trap shooting in an older version of the 682, until I was asked not to, not in the rules, unless factory fitted - I should have checked. The pattern compared with the mobils that were fitted was better. - I didn't really use them long enough to see the benefit, but if you always shoot bottom barrel first then one will do. Have a look at the teague web sight, there is some good technical stuff there.
Steve