Cheddite hulls are the way to go and one can get them from Graf's & Sons or Ballistic Products just about anytime they are needed.
The one wad for any size load up to 1 oz. is the Downrange DR16. It's designed specifically for the straight walled hulls and has a long crush section to allow the wad to apply the right amount of pressure for good fold crimps.
1 oz. loads in the 16 are nice, but I've been experimenting with 3/4 & 7/8 oz. loads lately and your really not giving up anything in these loads to the 1 oz load in the performance end of things. And you are getting more loads per bag of shot.
Cheddite hulls are definately "OK" for what's out there now. If you have access somehow to old Win AA's those are great. Old Active all plastic shells are pretty good if by chance you come across them.
Get on the Bakllistic Products website(
www.ballisticproducts.com), and get their 16 gauge load book. Best place for 16 information IMHO. I found their peasant load book lacking in 16 ga loads, and would reccomend "High performance loads for Clays" instead. BPI is big on using overshot wads, and they've now made a believier out of me.
There is a dearth of new information for the 16. You're going to have to do a lot of trial and error.
Good Luck!, Have Fun.
Joe