I have a Carlson .675 ported tube for my 835 that shoots very well,but the porting really snags the wad so Federal's Flight Control wad shells probably wouldent be any different then regular wad shells.
For a large variety of choke tubes try here
http://www.outdoorguides.com/outdoor/shottube.htm
Since I got my 870 SPS-T supermag I haven't been using my 835.
I had some lightfield deer slugs stick in the 835 deer barrel a few years ago but no shotshells
Bill